### 导航 - [索引](# "总目录") - [下一页](# "Flask 中的设计决策") | - [上一页](# "聚沙成塔") | - [Flask 0.10.1 文档](#) » # API 这部分文档涵盖了 Flask 的所有接口。对于那些 Flask 依赖外部库的部分，我们这里提供了最重要的部分的文档，并且提供其官方文档的链接。 ### 应用对象 *class *flask.Flask(*import_name*, *static_path=None*, *static_url_path=None*, *static_folder='static'*, *template_folder='templates'*, *instance_path=None*, *instance_relative_config=False*) The flask object implements a WSGI application and acts as the centralobject. It is passed the name of the module or package of theapplication. Once it is created it will act as a central registry forthe view functions, the URL rules, template configuration and much more. The name of the package is used to resolve resources from inside thepackage or the folder the module is contained in depending on if thepackage parameter resolves to an actual python package (a folder withan __init__.py file inside) or a standard module (just a .py file). For more information about resource loading, see [open_resource()](# "flask.Flask.open_resource"). Usually you create a [Flask](# "flask.Flask") instance in your main module orin the __init__.py file of your package like this: ~~~ from flask import Flask app = Flask(__name__) ~~~ About the First Parameter The idea of the first parameter is to give Flask an idea whatbelongs to your application. This name is used to find resourceson the file system, can be used by extensions to improve debugginginformation and a lot more. So it's important what you provide there. If you are using a singlemodule, __name__ is always the correct value. If you however areusing a package, it's usually recommended to hardcode the name ofyour package there. For example if your application is defined in yourapplication/app.pyyou should create it with one of the two versions below: ~~~ app = Flask('yourapplication') app = Flask(__name__.split('.')[0]) ~~~ Why is that? The application will work even with __name__, thanksto how resources are looked up. However it will make debugging morepainful. Certain extensions can make assumptions based on theimport name of your application. For example the Flask-SQLAlchemyextension will look for the code in your application that triggeredan SQL query in debug mode. If the import name is not properly setup, that debugging information is lost. (For example it would onlypick up SQL queries in yourapplication.app and notyourapplication.views.frontend) 0.7 新版功能: The static_url_path, static_folder, and template_folderparameters were added. 0.8 新版功能: The instance_path and instance_relative_config parameters wereadded. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>import_name</strong> – the name of the application package</li><li><strong>static_url_path</strong> – can be used to specify a different path for thestatic files on the web. Defaults to the nameof the <cite>static_folder</cite> folder.</li><li><strong>static_folder</strong> – the folder with static files that should be servedat <cite>static_url_path</cite>. Defaults to the <tt class="docutils literal"><span class="pre">'static'</span></tt>folder in the root path of the application.</li><li><strong>template_folder</strong> – the folder that contains the templates that shouldbe used by the application. Defaults to<tt class="docutils literal"><span class="pre">'templates'</span></tt> folder in the root path of theapplication.</li><li><strong>instance_path</strong> – An alternative instance path for the application.By default the folder <tt class="docutils literal"><span class="pre">'instance'</span></tt> next to thepackage or module is assumed to be the instancepath.</li><li><strong>instance_relative_config</strong> – if set to <cite>True</cite> relative filenamesfor loading the config are assumed tobe relative to the instance path insteadof the application root.</li></ul></td></tr></tbody></table> add_template_filter(**args*, ***kwargs*) Register a custom template filter. Works exactly like the[template_filter()](# "flask.Flask.template_filter") decorator. | 参数: | **name** – the optional name of the filter, otherwise thefunction name will be used. | |-----|-----| add_template_global(**args*, ***kwargs*) Register a custom template global function. Works exactly like the[template_global()](# "flask.Flask.template_global") decorator. 0.10 新版功能. | 参数: | **name** – the optional name of the global function, otherwise thefunction name will be used. | |-----|-----| add_template_test(**args*, ***kwargs*) Register a custom template test. Works exactly like the[template_test()](# "flask.Flask.template_test") decorator. 0.10 新版功能. | 参数: | **name** – the optional name of the test, otherwise thefunction name will be used. | |-----|-----| add_url_rule(**args*, ***kwargs*) Connects a URL rule. Works exactly like the [route()](# "flask.Flask.route")decorator. If a view_func is provided it will be registered with theendpoint. Basically this example: ~~~ @app.route('/') def index(): pass ~~~ Is equivalent to the following: ~~~ def index(): pass app.add_url_rule('/', 'index', index) ~~~ If the view_func is not provided you will need to connect the endpointto a view function like so: ~~~ app.view_functions['index'] = index ~~~ Internally [route()](# "flask.Flask.route") invokes [add_url_rule()](# "flask.Flask.add_url_rule") so if you wantto customize the behavior via subclassing you only need to changethis method. For more information refer to [*URL 路由注册*](#). 在 0.2 版更改: view_func parameter added. 在 0.6 版更改: OPTIONS is added automatically as method. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>rule</strong> – the URL rule as string</li><li><strong>endpoint</strong> – the endpoint for the registered URL rule. Flaskitself assumes the name of the view function asendpoint</li><li><strong>view_func</strong> – the function to call when serving a request to theprovided endpoint</li><li><strong>options</strong> – the options to be forwarded to the underlying<a class="reference external" href="http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule" title="(在 Werkzeug v0.10)"><tt class="xref py py-class docutils literal"><span class="pre">Rule</span></tt></a><span class="link-target"> [http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule]</span> object. A changeto Werkzeug is handling of method options. methodsis a list of methods this rule should be limitedto (<cite>GET</cite>, <cite>POST</cite> etc.). By default a rulejust listens for <cite>GET</cite> (and implicitly <cite>HEAD</cite>).Starting with Flask 0.6, <cite>OPTIONS</cite> is implicitlyadded and handled by the standard request handling.</li></ul></td></tr></tbody></table> after_request(**args*, ***kwargs*) Register a function to be run after each request. Your functionmust take one parameter, a [response_class](# "flask.Flask.response_class") object and returna new response object or the same (see [process_response()](# "flask.Flask.process_response")). As of Flask 0.7 this function might not be executed at the end of therequest in case an unhandled exception occurred. after_request_funcs* = None* A dictionary with lists of functions that should be called aftereach request. The key of the dictionary is the name of the blueprintthis function is active for, None for all requests. This can forexample be used to open database connections or getting hold of thecurrently logged in user. To register a function here, use the[after_request()](# "flask.Flask.after_request") decorator. app_context() Binds the application only. For as long as the application is boundto the current context the [flask.current_app](# "flask.current_app") points to thatapplication. An application context is automatically created when arequest context is pushed if necessary. Example usage: ~~~ with app.app_context(): ... ~~~ 0.9 新版功能. app_ctx_globals_class The class that is used for the [g](# "flask.g") instance. Example use cases for a custom class: 1. Store arbitrary attributes on flask.g. 1. Add a property for lazy per-request database connectors. 1. Return None instead of AttributeError on expected attributes. 1. Raise exception if an unexpected attr is set, a “controlled” flask.g. In Flask 0.9 this property was called request_globals_class but itwas changed in 0.10 to [app_ctx_globals_class](# "flask.Flask.app_ctx_globals_class") because theflask.g object is not application context scoped. 0.10 新版功能. _AppCtxGlobals 的别名 auto_find_instance_path() Tries to locate the instance path if it was not provided to theconstructor of the application class. It will basically calculatethe path to a folder named instance next to your main file orthe package. 0.8 新版功能. before_first_request(**args*, ***kwargs*) Registers a function to be run before the first request to thisinstance of the application. 0.8 新版功能. before_first_request_funcs* = None* A lists of functions that should be called at the beginning of thefirst request to this instance. To register a function here, usethe [before_first_request()](# "flask.Flask.before_first_request") decorator. 0.8 新版功能. before_request(**args*, ***kwargs*) Registers a function to run before each request. before_request_funcs* = None* A dictionary with lists of functions that should be called at thebeginning of the request. The key of the dictionary is the name ofthe blueprint this function is active for, None for all requests.This can for example be used to open database connections orgetting hold of the currently logged in user. To register afunction here, use the [before_request()](# "flask.Flask.before_request") decorator. blueprints* = None* all the attached blueprints in a dictionary by name. Blueprintscan be attached multiple times so this dictionary does not tellyou how often they got attached. 0.7 新版功能. config* = None* The configuration dictionary as [Config](# "flask.Config"). This behavesexactly like a regular dictionary but supports additional methodsto load a config from files. context_processor(**args*, ***kwargs*) Registers a template context processor function. create_global_jinja_loader() Creates the loader for the Jinja2 environment. Can be used tooverride just the loader and keeping the rest unchanged. It'sdiscouraged to override this function. Instead one should overridethe [jinja_loader()](# "flask.Flask.jinja_loader") function instead. The global loader dispatches between the loaders of the applicationand the individual blueprints. 0.7 新版功能. create_jinja_environment() Creates the Jinja2 environment based on [jinja_options](# "flask.Flask.jinja_options")and [select_jinja_autoescape()](# "flask.Flask.select_jinja_autoescape"). Since 0.7 this also addsthe Jinja2 globals and filters after initialization. Overridethis function to customize the behavior. 0.5 新版功能. create_url_adapter(*request*) Creates a URL adapter for the given request. The URL adapteris created at a point where the request context is not yet set upso the request is passed explicitly. 0.6 新版功能. 在 0.9 版更改: This can now also be called without a request object when theURL adapter is created for the application context. debug The debug flag. Set this to True to enable debugging of theapplication. In debug mode the debugger will kick in when an unhandledexception occurs and the integrated server will automatically reloadthe application if changes in the code are detected. This attribute can also be configured from the config with the DEBUGconfiguration key. Defaults to False. debug_log_format* = '--------------------------------------------------------------------------------\n%(levelname)s in %(module)s [%(pathname)s:%(lineno)d]:\n%(message)s\n--------------------------------------------------------------------------------'* The logging format used for the debug logger. This is only used whenthe application is in debug mode, otherwise the attached logginghandler does the formatting. 0.3 新版功能. default_config* = ImmutableDict({'JSON_AS_ASCII': True, 'USE_X_SENDFILE': False, 'SESSION_COOKIE_PATH': None, 'SESSION_COOKIE_DOMAIN': None, 'SESSION_COOKIE_NAME': 'session', 'LOGGER_NAME': None, 'DEBUG': False, 'SECRET_KEY': None, 'MAX_CONTENT_LENGTH': None, 'APPLICATION_ROOT': None, 'SERVER_NAME': None, 'PREFERRED_URL_SCHEME': 'http', 'JSONIFY_PRETTYPRINT_REGULAR': True, 'TESTING': False, 'PERMANENT_SESSION_LIFETIME': datetime.timedelta(31), 'PROPAGATE_EXCEPTIONS': None, 'TRAP_BAD_REQUEST_ERRORS': False, 'JSON_SORT_KEYS': True, 'SESSION_COOKIE_HTTPONLY': True, 'SEND_FILE_MAX_AGE_DEFAULT': 43200, 'PRESERVE_CONTEXT_ON_EXCEPTION': None, 'SESSION_COOKIE_SECURE': False, 'TRAP_HTTP_EXCEPTIONS': False})* Default configuration parameters. dispatch_request() Does the request dispatching. Matches the URL and returns thereturn value of the view or error handler. This does not have tobe a response object. In order to convert the return value to aproper response object, call [make_response()](# "flask.make_response"). 在 0.7 版更改: This no longer does the exception handling, this code wasmoved to the new [full_dispatch_request()](# "flask.Flask.full_dispatch_request"). do_teardown_appcontext(*exc=None*) Called when an application context is popped. This works prettymuch the same as [do_teardown_request()](# "flask.Flask.do_teardown_request") but for the applicationcontext. 0.9 新版功能. do_teardown_request(*exc=None*) Called after the actual request dispatching and willcall every as [teardown_request()](# "flask.Flask.teardown_request") decorated function. This isnot actually called by the [Flask](# "flask.Flask") object itself but is alwaystriggered when the request context is popped. That way we have atighter control over certain resources under testing environments. 在 0.9 版更改: Added the exc argument. Previously this was always using thecurrent exception information. enable_modules* = True* Enable the deprecated module support? This is active by defaultin 0.7 but will be changed to False in 0.8. With Flask 1.0 moduleswill be removed in favor of Blueprints endpoint(**args*, ***kwargs*) A decorator to register a function as an endpoint.Example: ~~~ @app.endpoint('example.endpoint') def example(): return "example" ~~~ | 参数: | **endpoint** – the name of the endpoint | |-----|-----| error_handler_spec* = None* A dictionary of all registered error handlers. The key is Nonefor error handlers active on the application, otherwise the key isthe name of the blueprint. Each key points to another dictionarywhere they key is the status code of the http exception. Thespecial key None points to a list of tuples where the first itemis the class for the instance check and the second the error handlerfunction. To register a error handler, use the [errorhandler()](# "flask.Flask.errorhandler")decorator. errorhandler(**args*, ***kwargs*) A decorator that is used to register a function give a givenerror code. Example: ~~~ @app.errorhandler(404) def page_not_found(error): return 'This page does not exist', 404 ~~~ You can also register handlers for arbitrary exceptions: ~~~ @app.errorhandler(DatabaseError) def special_exception_handler(error): return 'Database connection failed', 500 ~~~ You can also register a function as error handler without usingthe [errorhandler()](# "flask.Flask.errorhandler") decorator. The following example isequivalent to the one above: ~~~ def page_not_found(error): return 'This page does not exist', 404 app.error_handler_spec[None][404] = page_not_found ~~~ Setting error handlers via assignments to [error_handler_spec](# "flask.Flask.error_handler_spec")however is discouraged as it requires fiddling with nested dictionariesand the special case for arbitrary exception types. The first None refers to the active blueprint. If the errorhandler should be application wide None shall be used. 0.7 新版功能: One can now additionally also register custom exception typesthat do not necessarily have to be a subclass of theHTTPException class. | 参数: | **code** – the code as integer for the handler | |-----|-----| extensions* = None* a place where extensions can store application specific state. Forexample this is where an extension could store database engines andsimilar things. For backwards compatibility extensions should registerthemselves like this: ~~~ if not hasattr(app, 'extensions'): app.extensions = {} app.extensions['extensionname'] = SomeObject() ~~~ The key must match the name of the flaskext module. For example incase of a “Flask-Foo” extension in flaskext.foo, the key would be'foo'. 0.7 新版功能. full_dispatch_request() Dispatches the request and on top of that performs requestpre and postprocessing as well as HTTP exception catching anderror handling. 0.7 新版功能. get_send_file_max_age(*filename*) Provides default cache_timeout for the [send_file()](# "flask.send_file") functions. By default, this function returns SEND_FILE_MAX_AGE_DEFAULT fromthe configuration of [current_app](# "flask.current_app"). Static file functions such as [send_from_directory()](# "flask.send_from_directory") use thisfunction, and [send_file()](# "flask.send_file") calls this function on[current_app](# "flask.current_app") when the given cache_timeout is None. If acache_timeout is given in [send_file()](# "flask.send_file"), that timeout is used;otherwise, this method is called. This allows subclasses to change the behavior when sending files basedon the filename. For example, to set the cache timeout for .js filesto 60 seconds: ~~~ class MyFlask(flask.Flask): def get_send_file_max_age(self, name): if name.lower().endswith('.js'): return 60 return flask.Flask.get_send_file_max_age(self, name) ~~~ 0.9 新版功能. got_first_request This attribute is set to True if the application startedhandling the first request. 0.8 新版功能. handle_exception(*e*) Default exception handling that kicks in when an exceptionoccurs that is not caught. In debug mode the exception willbe re-raised immediately, otherwise it is logged and the handlerfor a 500 internal server error is used. If no such handlerexists, a default 500 internal server error message is displayed. 0.3 新版功能. handle_http_exception(*e*) Handles an HTTP exception. By default this will invoke theregistered error handlers and fall back to returning theexception as response. 0.3 新版功能. handle_url_build_error(*error*, *endpoint*, *values*) Handle BuildError on [url_for()](# "flask.url_for"). handle_user_exception(*e*) This method is called whenever an exception occurs that should behandled. A special case areHTTPExceptions which are forwarded bythis function to the [handle_http_exception()](# "flask.Flask.handle_http_exception") method. Thisfunction will either return a response value or reraise theexception with the same traceback. 0.7 新版功能. has_static_folder This is True if the package bound object's container has afolder named 'static'. 0.5 新版功能. init_jinja_globals() Deprecated. Used to initialize the Jinja2 globals. 0.5 新版功能. 在 0.7 版更改: This method is deprecated with 0.7. Override[create_jinja_environment()](# "flask.Flask.create_jinja_environment") instead. inject_url_defaults(*endpoint*, *values*) Injects the URL defaults for the given endpoint directly intothe values dictionary passed. This is used internally andautomatically called on URL building. 0.7 新版功能. instance_path* = None* Holds the path to the instance folder. 0.8 新版功能. jinja_env The Jinja2 environment used to load templates. jinja_loader The Jinja loader for this package bound object. 0.5 新版功能. jinja_options* = ImmutableDict({'extensions': ['jinja2.ext.autoescape', 'jinja2.ext.with_']})* Options that are passed directly to the Jinja2 environment. json_decoder The JSON decoder class to use. Defaults to [JSONDecoder](# "flask.json.JSONDecoder"). 0.10 新版功能. JSONDecoder 的别名 json_encoder The JSON encoder class to use. Defaults to [JSONEncoder](# "flask.json.JSONEncoder"). 0.10 新版功能. JSONEncoder 的别名 log_exception(*exc_info*) Logs an exception. This is called by [handle_exception()](# "flask.Flask.handle_exception")if debugging is disabled and right before the handler is called.The default implementation logs the exception as error on the[logger](# "flask.Flask.logger"). 0.8 新版功能. logger A [logging.Logger](http://docs.python.org/dev/library/logging.html#logging.Logger "(在 Python v3.5)") [http://docs.python.org/dev/library/logging.html#logging.Logger] object for this application. Thedefault configuration is to log to stderr if the application isin debug mode. This logger can be used to (surprise) log messages.Here some examples: ~~~ app.logger.debug('A value for debugging') app.logger.warning('A warning occurred (%d apples)', 42) app.logger.error('An error occurred') ~~~ 0.3 新版功能. logger_name The name of the logger to use. By default the logger name is thepackage name passed to the constructor. 0.4 新版功能. make_config(*instance_relative=False*) Used to create the config attribute by the Flask constructor.The instance_relative parameter is passed in from the constructorof Flask (there named instance_relative_config) and indicates ifthe config should be relative to the instance path or the root pathof the application. 0.8 新版功能. make_default_options_response() This method is called to create the default OPTIONS response.This can be changed through subclassing to change the defaultbehavior of OPTIONS responses. 0.7 新版功能. make_null_session() Creates a new instance of a missing session. Instead of overridingthis method we recommend replacing the [session_interface](# "flask.Flask.session_interface"). 0.7 新版功能. make_response(*rv*) Converts the return value from a view function to a realresponse object that is an instance of [response_class](# "flask.Flask.response_class"). The following types are allowed for rv: | [response_class](# "flask.Flask.response_class") | the object is returned unchanged | |-----|-----| | [str](http://docs.python.org/dev/library/stdtypes.html#str "(在 Python v3.5)") [http://docs.python.org/dev/library/stdtypes.html#str] | a response object is created with thestring as body | | unicode | a response object is created with thestring encoded to utf-8 as body | | a WSGI function | the function is called as WSGI applicationand buffered as response object | | [tuple](http://docs.python.org/dev/library/stdtypes.html#tuple "(在 Python v3.5)") [http://docs.python.org/dev/library/stdtypes.html#tuple] | A tuple in the form (response,status,headers) where response is any of thetypes defined here, status is a stringor an integer and headers is a list ofa dictionary with header values. | | 参数: | **rv** – the return value from the view function | |-----|-----| 在 0.9 版更改: Previously a tuple was interpreted as the arguments for theresponse object. name The name of the application. This is usually the import namewith the difference that it's guessed from the run file if theimport name is main. This name is used as a display name whenFlask needs the name of the application. It can be set and overriddento change the value. 0.8 新版功能. open_instance_resource(*resource*, *mode='rb'*) Opens a resource from the application's instance folder([instance_path](# "flask.Flask.instance_path")). Otherwise works like[open_resource()](# "flask.Flask.open_resource"). Instance resources can also be opened forwriting. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>resource</strong> – the name of the resource. To access resources withinsubfolders use forward slashes as separator.</li><li><strong>mode</strong> – resource file opening mode, default is ‘rb'.</li></ul></td></tr></tbody></table> open_resource(*resource*, *mode='rb'*) Opens a resource from the application's resource folder. To seehow this works, consider the following folder structure: ~~~ /myapplication.py /schema.sql /static /style.css /templates /layout.html /index.html ~~~ If you want to open the schema.sql file you would do thefollowing: ~~~ with app.open_resource('schema.sql') as f: contents = f.read() do_something_with(contents) ~~~ <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>resource</strong> – the name of the resource. To access resources withinsubfolders use forward slashes as separator.</li><li><strong>mode</strong> – resource file opening mode, default is ‘rb'.</li></ul></td></tr></tbody></table> open_session(*request*) Creates or opens a new session. Default implementation stores allsession data in a signed cookie. This requires that the[secret_key](# "flask.Flask.secret_key") is set. Instead of overriding this methodwe recommend replacing the [session_interface](# "flask.Flask.session_interface"). | 参数: | **request** – an instance of [request_class](# "flask.Flask.request_class"). | |-----|-----| permanent_session_lifetime A [timedelta](http://docs.python.org/dev/library/datetime.html#datetime.timedelta "(在 Python v3.5)") [http://docs.python.org/dev/library/datetime.html#datetime.timedelta] which is used to set the expirationdate of a permanent session. The default is 31 days which makes apermanent session survive for roughly one month. This attribute can also be configured from the config with thePERMANENT_SESSION_LIFETIME configuration key. Defaults totimedelta(days=31) preprocess_request() Called before the actual request dispatching and willcall every as [before_request()](# "flask.Flask.before_request") decorated function.If any of these function returns a value it's handled asif it was the return value from the view and furtherrequest handling is stopped. This also triggers the url_value_processor() functions beforethe actual [before_request()](# "flask.Flask.before_request") functions are called. preserve_context_on_exception Returns the value of the PRESERVE_CONTEXT_ON_EXCEPTIONconfiguration value in case it's set, otherwise a sensible defaultis returned. 0.7 新版功能. process_response(*response*) Can be overridden in order to modify the response objectbefore it's sent to the WSGI server. By default this willcall all the [after_request()](# "flask.Flask.after_request") decorated functions. 在 0.5 版更改: As of Flask 0.5 the functions registered for after requestexecution are called in reverse order of registration. | 参数: | **response** – a [response_class](# "flask.Flask.response_class") object. | |-----|-----| | 返回: | a new response object or the same, has to be aninstance of [response_class](# "flask.Flask.response_class"). | propagate_exceptions Returns the value of the PROPAGATE_EXCEPTIONS configurationvalue in case it's set, otherwise a sensible default is returned. 0.7 新版功能. register_blueprint(**args*, ***kwargs*) Registers a blueprint on the application. 0.7 新版功能. register_error_handler(*code_or_exception*, *f*) Alternative error attach function to the [errorhandler()](# "flask.Flask.errorhandler")decorator that is more straightforward to use for non decoratorusage. 0.7 新版功能. register_module(*module*, ***options*) Registers a module with this application. The keyword argumentof this function are the same as the ones for the constructor of theModule class and will override the values of the module ifprovided. 在 0.7 版更改: The module system was deprecated in favor for the blueprintsystem. request_class The class that is used for request objects. See [Request](# "flask.Request")for more information. [Request](# "flask.Request") 的别名 request_context(*environ*) Creates a [RequestContext](# "flask.ctx.RequestContext") from the givenenvironment and binds it to the current context. This must be used incombination with the with statement because the request is only boundto the current context for the duration of the with block. Example usage: ~~~ with app.request_context(environ): do_something_with(request) ~~~ The object returned can also be used without the with statementwhich is useful for working in the shell. The example above isdoing exactly the same as this code: ~~~ ctx = app.request_context(environ) ctx.push() try: do_something_with(request) finally: ctx.pop() ~~~ 在 0.3 版更改: Added support for non-with statement usage and with statementis now passed the ctx object. | 参数: | **environ** – a WSGI environment | |-----|-----| response_class The class that is used for response objects. See[Response](# "flask.Response") for more information. [Response](# "flask.Response") 的别名 route(*rule*, ***options*) A decorator that is used to register a view function for agiven URL rule. This does the same thing as [add_url_rule()](# "flask.Flask.add_url_rule")but is intended for decorator usage: ~~~ @app.route('/') def index(): return 'Hello World' ~~~ For more information refer to [*URL 路由注册*](#). <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>rule</strong> – the URL rule as string</li><li><strong>endpoint</strong> – the endpoint for the registered URL rule. Flaskitself assumes the name of the view function asendpoint</li><li><strong>options</strong> – the options to be forwarded to the underlying<a class="reference external" href="http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule" title="(在 Werkzeug v0.10)"><tt class="xref py py-class docutils literal"><span class="pre">Rule</span></tt></a><span class="link-target"> [http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule]</span> object. A changeto Werkzeug is handling of method options. methodsis a list of methods this rule should be limitedto (<cite>GET</cite>, <cite>POST</cite> etc.). By default a rulejust listens for <cite>GET</cite> (and implicitly <cite>HEAD</cite>).Starting with Flask 0.6, <cite>OPTIONS</cite> is implicitlyadded and handled by the standard request handling.</li></ul></td></tr></tbody></table> run(*host=None*, *port=None*, *debug=None*, ***options*) Runs the application on a local development server. If the[debug](# "flask.Flask.debug") flag is set the server will automatically reloadfor code changes and show a debugger in case an exception happened. If you want to run the application in debug mode, but disable thecode execution on the interactive debugger, you can passuse_evalex=False as parameter. This will keep the debugger'straceback screen active, but disable code execution. Keep in Mind Flask will suppress any server error with a generic error pageunless it is in debug mode. As such to enable just theinteractive debugger without the code reloading, you have toinvoke [run()](# "flask.Flask.run") with debug=True and use_reloader=False.Setting use_debugger to True without being in debug modewon't catch any exceptions because there won't be any tocatch. 在 0.10 版更改: The default port is now picked from the SERVER_NAME variable. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>host</strong> – the hostname to listen on. Set this to <tt class="docutils literal"><span class="pre">'0.0.0.0'</span></tt> tohave the server available externally as well. Defaults to<tt class="docutils literal"><span class="pre">'127.0.0.1'</span></tt>.</li><li><strong>port</strong> – the port of the webserver. Defaults to <tt class="docutils literal"><span class="pre">5000</span></tt> or theport defined in the <tt class="docutils literal"><span class="pre">SERVER_NAME</span></tt> config variable ifpresent.</li><li><strong>debug</strong> – if given, enable or disable debug mode.See <a class="reference internal" href="#flask.Flask.debug" title="flask.Flask.debug"><tt class="xref py py-attr docutils literal"><span class="pre">debug</span></tt></a>.</li><li><strong>options</strong> – the options to be forwarded to the underlyingWerkzeug server. See<a class="reference external" href="http://werkzeug.pocoo.org/docs/serving/#werkzeug.serving.run_simple" title="(在 Werkzeug v0.10)"><tt class="xref py py-func docutils literal"><span class="pre">werkzeug.serving.run_simple()</span></tt></a><span class="link-target"> [http://werkzeug.pocoo.org/docs/serving/#werkzeug.serving.run_simple]</span> for moreinformation.</li></ul></td></tr></tbody></table> save_session(*session*, *response*) Saves the session if it needs updates. For the defaultimplementation, check [open_session()](# "flask.Flask.open_session"). Instead of overriding thismethod we recommend replacing the [session_interface](# "flask.Flask.session_interface"). <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>session</strong> – the session to be saved (a<a class="reference external" href="http://werkzeug.pocoo.org/docs/contrib/securecookie/#werkzeug.contrib.securecookie.SecureCookie" title="(在 Werkzeug v0.10)"><tt class="xref py py-class docutils literal"><span class="pre">SecureCookie</span></tt></a><span class="link-target"> [http://werkzeug.pocoo.org/docs/contrib/securecookie/#werkzeug.contrib.securecookie.SecureCookie]</span>object)</li><li><strong>response</strong> – an instance of <a class="reference internal" href="#flask.Flask.response_class" title="flask.Flask.response_class"><tt class="xref py py-attr docutils literal"><span class="pre">response_class</span></tt></a></li></ul></td></tr></tbody></table> secret_key If a secret key is set, cryptographic components can use this tosign cookies and other things. Set this to a complex random valuewhen you want to use the secure cookie for instance. This attribute can also be configured from the config with theSECRET_KEY configuration key. Defaults to None. select_jinja_autoescape(*filename*) Returns True if autoescaping should be active for the giventemplate name. 0.5 新版功能. send_static_file(*filename*) Function used internally to send static files from the staticfolder to the browser. 0.5 新版功能. session_cookie_name The secure cookie uses this for the name of the session cookie. This attribute can also be configured from the config with theSESSION_COOKIE_NAME configuration key. Defaults to 'session' session_interface* = <flask.sessions.SecureCookieSessionInterface object at 0x3c9c7d0>* the session interface to use. By default an instance of[SecureCookieSessionInterface](# "flask.sessions.SecureCookieSessionInterface") is used here. 0.8 新版功能. should_ignore_error(*error*) This is called to figure out if an error should be ignoredor not as far as the teardown system is concerned. If thisfunction returns True then the teardown handlers will not bepassed the error. 0.10 新版功能. teardown_appcontext(**args*, ***kwargs*) Registers a function to be called when the application contextends. These functions are typically also called when the requestcontext is popped. Example: ~~~ ctx = app.app_context() ctx.push() ... ctx.pop() ~~~ When ctx.pop() is executed in the above example, the teardownfunctions are called just before the app context moves from thestack of active contexts. This becomes relevant if you are usingsuch constructs in tests. Since a request context typically also manages an applicationcontext it would also be called when you pop a request context. When a teardown function was called because of an exception it willbe passed an error object. 0.9 新版功能. teardown_appcontext_funcs* = None* A list of functions that are called when the application contextis destroyed. Since the application context is also torn downif the request ends this is the place to store code that disconnectsfrom databases. 0.9 新版功能. teardown_request(**args*, ***kwargs*) Register a function to be run at the end of each request,regardless of whether there was an exception or not. These functionsare executed when the request context is popped, even if not anactual request was performed. Example: ~~~ ctx = app.test_request_context() ctx.push() ... ctx.pop() ~~~ When ctx.pop() is executed in the above example, the teardownfunctions are called just before the request context moves from thestack of active contexts. This becomes relevant if you are usingsuch constructs in tests. Generally teardown functions must take every necessary step to avoidthat they will fail. If they do execute code that might fail theywill have to surround the execution of these code by try/exceptstatements and log occurring errors. When a teardown function was called because of a exception it willbe passed an error object. Debug Note In debug mode Flask will not tear down a request on an exceptionimmediately. Instead if will keep it alive so that the interactivedebugger can still access it. This behavior can be controlledby the PRESERVE_CONTEXT_ON_EXCEPTION configuration variable. teardown_request_funcs* = None* A dictionary with lists of functions that are called aftereach request, even if an exception has occurred. The key of thedictionary is the name of the blueprint this function is active for,None for all requests. These functions are not allowed to modifythe request, and their return values are ignored. If an exceptionoccurred while processing the request, it gets passed to eachteardown_request function. To register a function here, use the[teardown_request()](# "flask.Flask.teardown_request") decorator. 0.7 新版功能. template_context_processors* = None* A dictionary with list of functions that are called without argumentto populate the template context. The key of the dictionary is thename of the blueprint this function is active for, None for allrequests. Each returns a dictionary that the template context isupdated with. To register a function here, use the[context_processor()](# "flask.Flask.context_processor") decorator. template_filter(**args*, ***kwargs*) A decorator that is used to register custom template filter.You can specify a name for the filter, otherwise the functionname will be used. Example: ~~~ @app.template_filter() def reverse(s): return s[::-1] ~~~ | 参数: | **name** – the optional name of the filter, otherwise thefunction name will be used. | |-----|-----| template_global(**args*, ***kwargs*) A decorator that is used to register a custom template global function.You can specify a name for the global function, otherwise the functionname will be used. Example: ~~~ @app.template_global() def double(n): return 2 * n ~~~ 0.10 新版功能. | 参数: | **name** – the optional name of the global function, otherwise thefunction name will be used. | |-----|-----| template_test(**args*, ***kwargs*) A decorator that is used to register custom template test.You can specify a name for the test, otherwise the functionname will be used. Example: ~~~ @app.template_test() def is_prime(n): if n == 2: return True for i in range(2, int(math.ceil(math.sqrt(n))) + 1): if n % i == 0: return False return True ~~~ 0.10 新版功能. | 参数: | **name** – the optional name of the test, otherwise thefunction name will be used. | |-----|-----| test_client(*use_cookies=True*) Creates a test client for this application. For informationabout unit testing head over to [*测试 Flask 应用*](#). Note that if you are testing for assertions or exceptions in yourapplication code, you must set app.testing=True in order for theexceptions to propagate to the test client. Otherwise, the exceptionwill be handled by the application (not visible to the test client) andthe only indication of an AssertionError or other exception will be a500 status code response to the test client. See the [testing](# "flask.Flask.testing")attribute. For example: ~~~ app.testing = True client = app.test_client() ~~~ The test client can be used in a with block to defer the closing downof the context until the end of the with block. This is useful ifyou want to access the context locals for testing: ~~~ with app.test_client() as c: rv = c.get('/?vodka=42') assert request.args['vodka'] == '42' ~~~ See [FlaskClient](# "flask.testing.FlaskClient") for more information. 在 0.4 版更改: added support for with block usage for the client. 0.7 新版功能: The use_cookies parameter was added as well as the abilityto override the client to be used by setting the[test_client_class](# "flask.Flask.test_client_class") attribute. test_client_class* = None* the test client that is used with when test_client is used. 0.7 新版功能. test_request_context(**args*, ***kwargs*) Creates a WSGI environment from the given values (seewerkzeug.test.EnvironBuilder() for more information, thisfunction accepts the same arguments). testing The testing flag. Set this to True to enable the test mode ofFlask extensions (and in the future probably also Flask itself).For example this might activate unittest helpers that have anadditional runtime cost which should not be enabled by default. If this is enabled and PROPAGATE_EXCEPTIONS is not changed from thedefault it's implicitly enabled. This attribute can also be configured from the config with theTESTING configuration key. Defaults to False. trap_http_exception(*e*) Checks if an HTTP exception should be trapped or not. By defaultthis will return False for all exceptions except for a bad requestkey error if TRAP_BAD_REQUEST_ERRORS is set to True. Italso returns True if TRAP_HTTP_EXCEPTIONS is set to True. This is called for all HTTP exceptions raised by a view function.If it returns True for any exception the error handler for thisexception is not called and it shows up as regular exception in thetraceback. This is helpful for debugging implicitly raised HTTPexceptions. 0.8 新版功能. update_template_context(*context*) Update the template context with some commonly used variables.This injects request, session, config and g into the templatecontext as well as everything template context processors wantto inject. Note that the as of Flask 0.6, the original valuesin the context will not be overridden if a context processordecides to return a value with the same key. | 参数: | **context** – the context as a dictionary that is updated in placeto add extra variables. | |-----|-----| url_build_error_handlers* = None* A list of functions that are called when [url_for()](# "flask.url_for") raises aBuildError. Each function registered hereis called with error, endpoint and values. If a functionreturns None or raises a BuildError the next function istried. 0.9 新版功能. url_default_functions* = None* A dictionary with lists of functions that can be used as URL valuepreprocessors. The key None here is used for application widecallbacks, otherwise the key is the name of the blueprint.Each of these functions has the chance to modify the dictionaryof URL values before they are used as the keyword arguments of theview function. For each function registered this one should alsoprovide a [url_defaults()](# "flask.Flask.url_defaults") function that adds the parametersautomatically again that were removed that way. 0.7 新版功能. url_defaults(**args*, ***kwargs*) Callback function for URL defaults for all view functions of theapplication. It's called with the endpoint and values and shouldupdate the values passed in place. url_map* = None* The [Map](http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Map "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Map] for this instance. You can usethis to change the routing converters after the class was createdbut before any routes are connected. Example: ~~~ from werkzeug.routing import BaseConverter class ListConverter(BaseConverter): def to_python(self, value): return value.split(',') def to_url(self, values): return ','.join(BaseConverter.to_url(value) for value in values) app = Flask(__name__) app.url_map.converters['list'] = ListConverter ~~~ url_rule_class The rule object to use for URL rules created. This is used by[add_url_rule()](# "flask.Flask.add_url_rule"). Defaults to [werkzeug.routing.Rule](http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule]. 0.7 新版功能. Rule 的别名 url_value_preprocessor(**args*, ***kwargs*) Registers a function as URL value preprocessor for all viewfunctions of the application. It's called before the view functionsare called and can modify the url values provided. url_value_preprocessors* = None* A dictionary with lists of functions that can be used as URLvalue processor functions. Whenever a URL is built these functionsare called to modify the dictionary of values in place. The keyNone here is used for application widecallbacks, otherwise the key is the name of the blueprint.Each of these functions has the chance to modify the dictionary 0.7 新版功能. use_x_sendfile Enable this if you want to use the X-Sendfile feature. Keep inmind that the server has to support this. This only affects filessent with the [send_file()](# "flask.send_file") method. 0.2 新版功能. This attribute can also be configured from the config with theUSE_X_SENDFILE configuration key. Defaults to False. view_functions* = None* A dictionary of all view functions registered. The keys willbe function names which are also used to generate URLs andthe values are the function objects themselves.To register a view function, use the [route()](# "flask.Flask.route") decorator. wsgi_app(*environ*, *start_response*) The actual WSGI application. This is not implemented in__call__ so that middlewares can be applied without losing areference to the class. So instead of doing this: ~~~ app = MyMiddleware(app) ~~~ It's a better idea to do this instead: ~~~ app.wsgi_app = MyMiddleware(app.wsgi_app) ~~~ Then you still have the original application object around andcan continue to call methods on it. 在 0.7 版更改: The behavior of the before and after request callbacks was changedunder error conditions and a new callback was added that willalways execute at the end of the request, independent on if anerror occurred or not. See [*回调和错误*](#). <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>environ</strong> – a WSGI environment</li><li><strong>start_response</strong> – a callable accepting a status code,a list of headers and an optionalexception context to start the response</li></ul></td></tr></tbody></table> ### 蓝图对象 *class *flask.Blueprint(*name*, *import_name*, *static_folder=None*, *static_url_path=None*, *template_folder=None*, *url_prefix=None*, *subdomain=None*, *url_defaults=None*) Represents a blueprint. A blueprint is an object that recordsfunctions that will be called with theBlueprintSetupState later to register functionsor other things on the main application. See [*用蓝图实现模块化的应用*](#) for moreinformation. 0.7 新版功能. add_app_template_filter(*f*, *name=None*) Register a custom template filter, available application wide. Like[Flask.add_template_filter()](# "flask.Flask.add_template_filter") but for a blueprint. Works exactlylike the [app_template_filter()](# "flask.Blueprint.app_template_filter") decorator. | 参数: | **name** – the optional name of the filter, otherwise thefunction name will be used. | |-----|-----| add_app_template_global(*f*, *name=None*) Register a custom template global, available application wide. Like[Flask.add_template_global()](# "flask.Flask.add_template_global") but for a blueprint. Works exactlylike the [app_template_global()](# "flask.Blueprint.app_template_global") decorator. 0.10 新版功能. | 参数: | **name** – the optional name of the global, otherwise thefunction name will be used. | |-----|-----| add_app_template_test(*f*, *name=None*) Register a custom template test, available application wide. Like[Flask.add_template_test()](# "flask.Flask.add_template_test") but for a blueprint. Works exactlylike the [app_template_test()](# "flask.Blueprint.app_template_test") decorator. 0.10 新版功能. | 参数: | **name** – the optional name of the test, otherwise thefunction name will be used. | |-----|-----| add_url_rule(*rule*, *endpoint=None*, *view_func=None*, ***options*) Like [Flask.add_url_rule()](# "flask.Flask.add_url_rule") but for a blueprint. The endpoint forthe [url_for()](# "flask.url_for") function is prefixed with the name of the blueprint. after_app_request(*f*) Like [Flask.after_request()](# "flask.Flask.after_request") but for a blueprint. Such a functionis executed after each request, even if outside of the blueprint. after_request(*f*) Like [Flask.after_request()](# "flask.Flask.after_request") but for a blueprint. This functionis only executed after each request that is handled by a function ofthat blueprint. app_context_processor(*f*) Like [Flask.context_processor()](# "flask.Flask.context_processor") but for a blueprint. Such afunction is executed each request, even if outside of the blueprint. app_errorhandler(*code*) Like [Flask.errorhandler()](# "flask.Flask.errorhandler") but for a blueprint. Thishandler is used for all requests, even if outside of the blueprint. app_template_filter(*name=None*) Register a custom template filter, available application wide. Like[Flask.template_filter()](# "flask.Flask.template_filter") but for a blueprint. | 参数: | **name** – the optional name of the filter, otherwise thefunction name will be used. | |-----|-----| app_template_global(*name=None*) Register a custom template global, available application wide. Like[Flask.template_global()](# "flask.Flask.template_global") but for a blueprint. 0.10 新版功能. | 参数: | **name** – the optional name of the global, otherwise thefunction name will be used. | |-----|-----| app_template_test(*name=None*) Register a custom template test, available application wide. Like[Flask.template_test()](# "flask.Flask.template_test") but for a blueprint. 0.10 新版功能. | 参数: | **name** – the optional name of the test, otherwise thefunction name will be used. | |-----|-----| app_url_defaults(*f*) Same as [url_defaults()](# "flask.Blueprint.url_defaults") but application wide. app_url_value_preprocessor(*f*) Same as [url_value_preprocessor()](# "flask.Blueprint.url_value_preprocessor") but application wide. before_app_first_request(*f*) Like [Flask.before_first_request()](# "flask.Flask.before_first_request"). Such a function isexecuted before the first request to the application. before_app_request(*f*) Like [Flask.before_request()](# "flask.Flask.before_request"). Such a function is executedbefore each request, even if outside of a blueprint. before_request(*f*) Like [Flask.before_request()](# "flask.Flask.before_request") but for a blueprint. This functionis only executed before each request that is handled by a function ofthat blueprint. context_processor(*f*) Like [Flask.context_processor()](# "flask.Flask.context_processor") but for a blueprint. Thisfunction is only executed for requests handled by a blueprint. endpoint(*endpoint*) Like [Flask.endpoint()](# "flask.Flask.endpoint") but for a blueprint. This does notprefix the endpoint with the blueprint name, this has to be doneexplicitly by the user of this method. If the endpoint is prefixedwith a . it will be registered to the current blueprint, otherwiseit's an application independent endpoint. errorhandler(*code_or_exception*) Registers an error handler that becomes active for this blueprintonly. Please be aware that routing does not happen local to ablueprint so an error handler for 404 usually is not handled bya blueprint unless it is caused inside a view function. Anotherspecial case is the 500 internal server error which is always lookedup from the application. Otherwise works as the [errorhandler()](# "flask.Flask.errorhandler") decoratorof the [Flask](# "flask.Flask") object. get_send_file_max_age(*filename*) Provides default cache_timeout for the [send_file()](# "flask.send_file") functions. By default, this function returns SEND_FILE_MAX_AGE_DEFAULT fromthe configuration of [current_app](# "flask.current_app"). Static file functions such as [send_from_directory()](# "flask.send_from_directory") use thisfunction, and [send_file()](# "flask.send_file") calls this function on[current_app](# "flask.current_app") when the given cache_timeout is None. If acache_timeout is given in [send_file()](# "flask.send_file"), that timeout is used;otherwise, this method is called. This allows subclasses to change the behavior when sending files basedon the filename. For example, to set the cache timeout for .js filesto 60 seconds: ~~~ class MyFlask(flask.Flask): def get_send_file_max_age(self, name): if name.lower().endswith('.js'): return 60 return flask.Flask.get_send_file_max_age(self, name) ~~~ 0.9 新版功能. has_static_folder This is True if the package bound object's container has afolder named 'static'. 0.5 新版功能. jinja_loader The Jinja loader for this package bound object. 0.5 新版功能. make_setup_state(*app*, *options*, *first_registration=False*) Creates an instance of [BlueprintSetupState()](# "flask.blueprints.BlueprintSetupState")object that is later passed to the register callback functions.Subclasses can override this to return a subclass of the setup state. open_resource(*resource*, *mode='rb'*) Opens a resource from the application's resource folder. To seehow this works, consider the following folder structure: ~~~ /myapplication.py /schema.sql /static /style.css /templates /layout.html /index.html ~~~ If you want to open the schema.sql file you would do thefollowing: ~~~ with app.open_resource('schema.sql') as f: contents = f.read() do_something_with(contents) ~~~ <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>resource</strong> – the name of the resource. To access resources withinsubfolders use forward slashes as separator.</li><li><strong>mode</strong> – resource file opening mode, default is ‘rb'.</li></ul></td></tr></tbody></table> record(*func*) Registers a function that is called when the blueprint isregistered on the application. This function is called with thestate as argument as returned by the [make_setup_state()](# "flask.Blueprint.make_setup_state")method. record_once(*func*) Works like [record()](# "flask.Blueprint.record") but wraps the function in anotherfunction that will ensure the function is only called once. If theblueprint is registered a second time on the application, thefunction passed is not called. register(*app*, *options*, *first_registration=False*) Called by [Flask.register_blueprint()](# "flask.Flask.register_blueprint") to register a blueprinton the application. This can be overridden to customize the registerbehavior. Keyword arguments from[register_blueprint()](# "flask.Flask.register_blueprint") are directly forwarded to thismethod in the options dictionary. route(*rule*, ***options*) Like [Flask.route()](# "flask.Flask.route") but for a blueprint. The endpoint for the[url_for()](# "flask.url_for") function is prefixed with the name of the blueprint. send_static_file(*filename*) Function used internally to send static files from the staticfolder to the browser. 0.5 新版功能. teardown_app_request(*f*) Like [Flask.teardown_request()](# "flask.Flask.teardown_request") but for a blueprint. Such afunction is executed when tearing down each request, even if outside ofthe blueprint. teardown_request(*f*) Like [Flask.teardown_request()](# "flask.Flask.teardown_request") but for a blueprint. Thisfunction is only executed when tearing down requests handled by afunction of that blueprint. Teardown request functions are executedwhen the request context is popped, even when no actual request wasperformed. url_defaults(*f*) Callback function for URL defaults for this blueprint. It's calledwith the endpoint and values and should update the values passedin place. url_value_preprocessor(*f*) Registers a function as URL value preprocessor for thisblueprint. It's called before the view functions are called andcan modify the url values provided. ### 进入的请求对象 *class *flask.Request(*environ*, *populate_request=True*, *shallow=False*) The request object used by default in Flask. Remembers thematched endpoint and view arguments. It is what ends up as [request](# "flask.request"). If you want to replacethe request object used you can subclass this and set[request_class](# "flask.Flask.request_class") to your subclass. The request object is a [Request](http://werkzeug.pocoo.org/docs/wrappers/#werkzeug.wrappers.Request "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/wrappers/#werkzeug.wrappers.Request] subclass andprovides all of the attributes Werkzeug defines plus a few Flaskspecific ones. form 一个包含解析过的从 POST 或 PUT 请求发送的表单对象的[MultiDict](http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.MultiDict "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.MultiDict] 。请注意上传的文件不会在这里，而是在[files](# "flask.Request.files") 属性中。 args 一个包含解析过的查询字符串（ URL 中问号后的部分）内容的[MultiDict](http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.MultiDict "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.MultiDict] 。 values 一个包含 [form](# "flask.Request.form") 和 [args](# "flask.Request.args") 全部内容的[CombinedMultiDict](http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.CombinedMultiDict "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.CombinedMultiDict] 。 cookies 一个包含请求中传送的所有 cookie 内容的 [dict](http://docs.python.org/dev/library/stdtypes.html#dict "(在 Python v3.5)") [http://docs.python.org/dev/library/stdtypes.html#dict] 。 stream 如果表单提交的数据没有以已知的 mimetype 编码，为性能考虑，数据会不经修改存储在这个流中。大多数情况下，使用可以把数据提供为字符串的[data](# "flask.Request.data") 是更好的方法。流只返回一次数据。 headers 进入请求的标头存为一个类似字典的对象。 data 如果进入的请求数据是 Flask 不能处理的 mimetype ，数据将作为字符串存于此。 files 一个包含 POST 和 PUT 请求中上传的文件的[MultiDict](http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.MultiDict "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.MultiDict] 。每个文件存储为[FileStorage](http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.FileStorage "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.FileStorage] 对象。其基本的行为类似你在 Python 中见到的标准文件对象，差异在于这个对象有一个[save()](http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.FileStorage.save "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/datastructures/#werkzeug.datastructures.FileStorage.save] 方法可以把文件存储到文件系统上。 environ 底层的 WSGI 环境。 method 当前请求的 HTTP 方法 (POST ， GET 等等) pathscript_rooturlbase_urlurl_root 提供不同的方式来审视当前的 URL 。想象你的应用监听下面的 URL: ~~~ http://www.example.com/myapplication ~~~ 并且用户请求下面的 URL: ~~~ http://www.example.com/myapplication/page.html?x=y ~~~ 这个情况下，上面提到的属性的值会为如下: | path | /page.html | |-----|-----| | script_root | /myapplication | | base_url | http://www.example.com/myapplication/page.html | | url | http://www.example.com/myapplication/page.html?x=y | | url_root | http://www.example.com/myapplication/ | is_xhr 当请求由 JavaScript 的 XMLHttpRequest 触发时，该值为 True 。这只对支持 X-Requested-With 标头并把该标头设置为XMLHttpRequest 的库奏效。这么做的库有 prototype 、 jQuery 以及Mochikit 等更多。 blueprint The name of the current blueprint endpoint The endpoint that matched the request. This in combination with[view_args](# "flask.Request.view_args") can be used to reconstruct the same or amodified URL. If an exception happened when matching, this willbe None. get_json(*force=False*, *silent=False*, *cache=True*) Parses the incoming JSON request data and returns it. Ifparsing fails the [on_json_loading_failed()](# "flask.Request.on_json_loading_failed") method on therequest object will be invoked. By default this function willonly load the json data if the mimetype is application/jsonbut this can be overriden by the force parameter. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>force</strong> – if set to <cite>True</cite> the mimetype is ignored.</li><li><strong>silent</strong> – if set to <cite>False</cite> this method will fail silentlyand return <cite>False</cite>.</li><li><strong>cache</strong> – if set to <cite>True</cite> the parsed JSON data is rememberedon the request.</li></ul></td></tr></tbody></table> json If the mimetype is application/json this will contain theparsed JSON data. Otherwise this will be None. The [get_json()](# "flask.Request.get_json") method should be used instead. max_content_length Read-only view of the MAX_CONTENT_LENGTH config key. module The name of the current module if the request was dispatchedto an actual module. This is deprecated functionality, use blueprintsinstead. on_json_loading_failed(*e*) Called if decoding of the JSON data failed. The return value ofthis method is used by [get_json()](# "flask.Request.get_json") when an error occurred. Thedefault implementation just raises a BadRequest exception. 在 0.10 版更改: Removed buggy previous behavior of generating a random JSONresponse. If you want that behavior back you can triviallyadd it by subclassing. 0.8 新版功能. routing_exception* = None* if matching the URL failed, this is the exception that will beraised / was raised as part of the request handling. This isusually a [NotFound](http://werkzeug.pocoo.org/docs/exceptions/#werkzeug.exceptions.NotFound "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/exceptions/#werkzeug.exceptions.NotFound] exception orsomething similar. url_rule* = None* the internal URL rule that matched the request. This can beuseful to inspect which methods are allowed for the URL froma before/after handler (request.url_rule.methods) etc. 0.6 新版功能. view_args* = None* a dict of view arguments that matched the request. If an exceptionhappened when matching, this will be None. *class *flask.request 你可以使用全局 request 对象访问进入的请求数据。 Flask 处理进入的请求数据并允许你用这个全局对象访问它。如果你工作在多线程环境，Flask 内部保证你总会在当前线程上获取正确的数据， 这是一个代理。详情见 [*留意代理*](#) 。 请求对象是一个 [Request](http://werkzeug.pocoo.org/docs/wrappers/#werkzeug.wrappers.Request "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/wrappers/#werkzeug.wrappers.Request] 子类的实例，提供所有Werkzeug 定义的属性。这里只对最重要的展示了简要概述。 ### 响应对象 *class *flask.Response(*response=None*, *status=None*, *headers=None*, *mimetype=None*, *content_type=None*, *direct_passthrough=False*) The response object that is used by default in Flask. Works like theresponse object from Werkzeug but is set to have an HTML mimetype bydefault. Quite often you don't have to create this object yourself because[make_response()](# "flask.Flask.make_response") will take care of that for you. If you want to replace the response object used you can subclass this andset [response_class](# "flask.Flask.response_class") to your subclass. headers Headers 对象表示响应的标头。 status 字符串表示的响应状态。 status_code 整数表示的响应状态。 data A descriptor that calls get_data() and set_data(). Thisshould not be used and will eventually get deprecated. mimetype The mimetype (content type without charset etc.) set_cookie(*key*, *value=''*, *max_age=None*, *expires=None*, *path='/'*, *domain=None*, *secure=None*, *httponly=False*) Sets a cookie. The parameters are the same as in the cookie Morselobject in the Python standard library but it accepts unicode data, too. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>key</strong> – the key (name) of the cookie to be set.</li><li><strong>value</strong> – the value of the cookie.</li><li><strong>max_age</strong> – should be a number of seconds, or <cite>None</cite> (default) ifthe cookie should last only as long as the client'sbrowser session.</li><li><strong>expires</strong> – should be a <cite>datetime</cite> object or UNIX timestamp.</li><li><strong>domain</strong> – if you want to set a cross-domain cookie. For example,<tt class="docutils literal"><span class="pre">domain=".example.com"</span></tt> will set a cookie that isreadable by the domain <tt class="docutils literal"><span class="pre">www.example.com</span></tt>,<tt class="docutils literal"><span class="pre">foo.example.com</span></tt> etc. Otherwise, a cookie will onlybe readable by the domain that set it.</li><li><strong>path</strong> – limits the cookie to a given path, per default it willspan the whole domain.</li></ul></td></tr></tbody></table> ### 会话 如果你设置了 [Flask.secret_key](# "flask.Flask.secret_key") ，你可以在 Flask 应用中使用会话。会话主要使得在请求见保留信息成为可能。 Flask 的实现方法是使用一个签名的 cookie 。这样，用户可以查看会话的内容，但是不能修改它，除非用户知道密钥。所以确保密钥被设置为一个复杂且无法被容易猜测的值。 你可以使用 [session](# "flask.session") 对象来访问当前的会话: *class *flask.session 会话对象很像通常的字典，区别是会话对象会追踪修改。 这是一个代理。更多信息见 [*留意代理*](#) 。 下列属性是需要关注的: new 如果会话是新的，该值为 True ，否则为 False 。 modified 当果会话对象检测到修改，这个值为 True 。注意可变结构的修改不会被自动捕获，这种情况下你需要自行显式地设置这个属性为 True 。这里有 一个例子: ~~~ # this change is not picked up because a mutable object (here # a list) is changed. session['objects'].append(42) # so mark it as modified yourself session.modified = True ~~~ permanent 如果设为 True ，会话存活[permanent_session_lifetime](# "flask.Flask.permanent_session_lifetime") 秒。默认为 31 天。如果是 False （默认选项），会话会在用户关闭浏览器时删除。 ### 会话接口 0.8 新版功能. 会话接口提供了简单的途径来替换 Flask 正在使用的会话实现。 *class *flask.sessions.SessionInterface The basic interface you have to implement in order to replace thedefault session interface which uses werkzeug's securecookieimplementation. The only methods you have to implement are[open_session()](# "flask.sessions.SessionInterface.open_session") and [save_session()](# "flask.sessions.SessionInterface.save_session"), the others haveuseful defaults which you don't need to change. The session object returned by the [open_session()](# "flask.sessions.SessionInterface.open_session") method has toprovide a dictionary like interface plus the properties and methodsfrom the [SessionMixin](# "flask.sessions.SessionMixin"). We recommend just subclassing a dictand adding that mixin: ~~~ class Session(dict, SessionMixin): pass ~~~ If [open_session()](# "flask.sessions.SessionInterface.open_session") returns None Flask will call into[make_null_session()](# "flask.sessions.SessionInterface.make_null_session") to create a session that acts as replacementif the session support cannot work because some requirement is notfulfilled. The default [NullSession](# "flask.sessions.NullSession") class that is createdwill complain that the secret key was not set. To replace the session interface on an application all you have to dois to assign [flask.Flask.session_interface](# "flask.Flask.session_interface"): ~~~ app = Flask(__name__) app.session_interface = MySessionInterface() ~~~ 0.8 新版功能. get_cookie_domain(*app*) Helpful helper method that returns the cookie domain that shouldbe used for the session cookie if session cookies are used. get_cookie_httponly(*app*) Returns True if the session cookie should be httponly. Thiscurrently just returns the value of the SESSION_COOKIE_HTTPONLYconfig var. get_cookie_path(*app*) Returns the path for which the cookie should be valid. Thedefault implementation uses the value from the SESSION_COOKIE_PATH``config var if it's set, and falls back to APPLICATION_ROOT oruses / if it's None. get_cookie_secure(*app*) Returns True if the cookie should be secure. This currentlyjust returns the value of the SESSION_COOKIE_SECURE setting. get_expiration_time(*app*, *session*) A helper method that returns an expiration date for the sessionor None if the session is linked to the browser session. Thedefault implementation returns now + the permanent sessionlifetime configured on the application. is_null_session(*obj*) Checks if a given object is a null session. Null sessions arenot asked to be saved. This checks if the object is an instance of [null_session_class](# "flask.sessions.SessionInterface.null_session_class")by default. make_null_session(*app*) Creates a null session which acts as a replacement object if thereal session support could not be loaded due to a configurationerror. This mainly aids the user experience because the job of thenull session is to still support lookup without complaining butmodifications are answered with a helpful error message of whatfailed. This creates an instance of [null_session_class](# "flask.sessions.SessionInterface.null_session_class") by default. null_session_class [make_null_session()](# "flask.sessions.SessionInterface.make_null_session") will look here for the class that shouldbe created when a null session is requested. Likewise the[is_null_session()](# "flask.sessions.SessionInterface.is_null_session") method will perform a typecheck againstthis type. [NullSession](# "flask.sessions.NullSession") 的别名 open_session(*app*, *request*) This method has to be implemented and must either return Nonein case the loading failed because of a configuration error or aninstance of a session object which implements a dictionary likeinterface + the methods and attributes on [SessionMixin](# "flask.sessions.SessionMixin"). pickle_based* = False* A flag that indicates if the session interface is pickle based.This can be used by flask extensions to make a decision in regardsto how to deal with the session object. 0.10 新版功能. save_session(*app*, *session*, *response*) This is called for actual sessions returned by [open_session()](# "flask.sessions.SessionInterface.open_session")at the end of the request. This is still called during a requestcontext so if you absolutely need access to the request you can dothat. *class *flask.sessions.SecureCookieSessionInterface The default session interface that stores sessions in signed cookiesthrough the itsdangerous module. digest_method() the hash function to use for the signature. The default is sha1 key_derivation* = 'hmac'* the name of the itsdangerous supported key derivation. The defaultis hmac. salt* = 'cookie-session'* the salt that should be applied on top of the secret key for thesigning of cookie based sessions. serializer* = <flask.sessions.TaggedJSONSerializer object at 0x3c9c390>* A python serializer for the payload. The default is a compactJSON derived serializer with support for some extra Python typessuch as datetime objects or tuples. session_class SecureCookieSession 的别名 *class *flask.sessions.NullSession(*initial=None*) Class used to generate nicer error messages if sessions are notavailable. Will still allow read-only access to the empty sessionbut fail on setting. *class *flask.sessions.SessionMixin Expands a basic dictionary with an accessors that are expectedby Flask extensions and users for the session. modified* = True* for some backends this will always be True, but some backends willdefault this to false and detect changes in the dictionary for aslong as changes do not happen on mutable structures in the session.The default mixin implementation just hardcodes True in. new* = False* some session backends can tell you if a session is new, but that isnot necessarily guaranteed. Use with caution. The default mixinimplementation just hardcodes False in. permanent this reflects the '_permanent' key in the dict. flask.sessions.session_json_serializer Notice PERMANENT_SESSION_LIFETIME 配置键从 Flask 0.8 开始可以是一个整数。你可以自己计算值，或用应用上的[permanent_session_lifetime](# "flask.Flask.permanent_session_lifetime") 属性来自动转换结果为一个整数。 ### 测试客户端 *class *flask.testing.FlaskClient(*application*, *response_wrapper=None*, *use_cookies=True*, *allow_subdomain_redirects=False*) Works like a regular Werkzeug test client but has some knowledge abouthow Flask works to defer the cleanup of the request context stack to theend of a with body when used in a with statement. For general informationabout how to use this class refer to [werkzeug.test.Client](http://werkzeug.pocoo.org/docs/test/#werkzeug.test.Client "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/test/#werkzeug.test.Client]. Basic usage is outlined in the [*测试 Flask 应用*](#) chapter. session_transaction(**args*, ***kwds*) When used in combination with a with statement this opens asession transaction. This can be used to modify the session thatthe test client uses. Once the with block is left the session isstored back. > with client.session_transaction() as session:session[‘value'] = 42 Internally this is implemented by going through a temporary testrequest context and since session handling could depend onrequest variables this function accepts the same arguments as[test_request_context()](# "flask.Flask.test_request_context") which are directlypassed through. ### 应用全局变量 只在一个请求内，从一个函数到另一个函数共享数据，全局变量并不够好。因为这在线程环境下行不通。 Flask 提供了一个特殊的对象来确保只在活动的请求中有效，并且每个请求都返回不同的值。一言蔽之：它做正确的事情，如同它对[request](# "flask.request") 和 [session](# "flask.session") 做的那样。 flask.g 在这上存储你任何你想要存储的。例如一个数据库连接或者当前登入的用户。 从 Flask 0.10 起，对象 g 存储在应用上下文中而不再是请求上下文中，这意味着即使在应用上下文中它也是可访问的而不是只能在请求上下文中。在结合 [*伪造资源和上下文*](#) 模式使用来测试时这尤为有用。 另外，在 0.10 中你可以使用 get() 方法来获取一个属性或者如果这个属性没设置的话将得到 None (或者第二个参数)。这两种用法现在是没有区别的: ~~~ user = getattr(flask.g, 'user', None) user = flask.get.get('user', None) ~~~ 现在也能在 g 对象上使用 in 运算符来确定它是否有某个属性，并且它将使用 yield 关键字来生成这样一个可迭代的包含所有keys的生成器。 这是一个代理。详情见 [*留意代理*](#) 。 ### 有用的函数和类 flask.current_app 指向正在处理请求的应用。这对于想要支持同时运行多个应用的扩展有用。它由应用上下文驱动，而不是请求上下文，所以你可以用[app_context()](# "flask.Flask.app_context") 方法修改这个代理的值。 这是一个代理。详情见 [*留意代理*](#) 。 flask.has_request_context() If you have code that wants to test if a request context is there ornot this function can be used. For instance, you may want to take advantageof request information if the request object is available, but failsilently if it is unavailable. ~~~ class User(db.Model): def __init__(self, username, remote_addr=None): self.username = username if remote_addr is None and has_request_context(): remote_addr = request.remote_addr self.remote_addr = remote_addr ~~~ Alternatively you can also just test any of the context bound objects(such as [request](# "flask.request") or [g](# "flask.g") for truthness): ~~~ class User(db.Model): def __init__(self, username, remote_addr=None): self.username = username if remote_addr is None and request: remote_addr = request.remote_addr self.remote_addr = remote_addr ~~~ 0.7 新版功能. flask.has_app_context() Works like [has_request_context()](# "flask.has_request_context") but for the applicationcontext. You can also just do a boolean check on the[current_app](# "flask.current_app") object instead. 0.9 新版功能. flask.url_for(*endpoint*, ***values*) Generates a URL to the given endpoint with the method provided. Variable arguments that are unknown to the target endpoint are appendedto the generated URL as query arguments. If the value of a query argumentis None, the whole pair is skipped. In case blueprints are activeyou can shortcut references to the same blueprint by prefixing thelocal endpoint with a dot (.). This will reference the index function local to the current blueprint: ~~~ url_for('.index') ~~~ For more information, head over to the [*Quickstart*](#). To integrate applications, [Flask](# "flask.Flask") has a hook to intercept URL builderrors through Flask.build_error_handler. The url_for functionresults in a BuildError when the current app doesnot have a URL for the given endpoint and values. When it does, the[current_app](# "flask.current_app") calls its build_error_handler ifit is not None, which can return a string to use as the result ofurl_for (instead of url_for‘s default to raise theBuildError exception) or re-raise the exception.An example: ~~~ def external_url_handler(error, endpoint, **values): "Looks up an external URL when `url_for` cannot build a URL." # This is an example of hooking the build_error_handler. # Here, lookup_url is some utility function you've built # which looks up the endpoint in some external URL registry. url = lookup_url(endpoint, **values) if url is None: # External lookup did not have a URL. # Re-raise the BuildError, in context of original traceback. exc_type, exc_value, tb = sys.exc_info() if exc_value is error: raise exc_type, exc_value, tb else: raise error # url_for will use this result, instead of raising BuildError. return url app.build_error_handler = external_url_handler ~~~ Here, error is the instance of BuildError, andendpoint and **values are the arguments passed into url_for. Notethat this is for building URLs outside the current application, and not forhandling 404 NotFound errors. 0.10 新版功能: The _scheme parameter was added. 0.9 新版功能: The _anchor and _method parameters were added. 0.9 新版功能: Calls Flask.handle_build_error() onBuildError. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>endpoint</strong> – the endpoint of the URL (name of the function)</li><li><strong>values</strong> – the variable arguments of the URL rule</li><li><strong>_external</strong> – if set to <cite>True</cite>, an absolute URL is generated. Serveraddress can be changed via <cite>SERVER_NAME</cite> configuration variable whichdefaults to <cite>localhost</cite>.</li><li><strong>_scheme</strong> – a string specifying the desired URL scheme. The <cite>_external</cite>parameter must be set to <cite>True</cite> or a <cite>ValueError</cite> is raised.</li><li><strong>_anchor</strong> – if provided this is added as anchor to the URL.</li><li><strong>_method</strong> – if provided this explicitly specifies an HTTP method.</li></ul></td></tr></tbody></table> flask.abort(*code*) 抛出一个给定状态代码的 [HTTPException](http://werkzeug.pocoo.org/docs/exceptions/#werkzeug.exceptions.HTTPException "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/exceptions/#werkzeug.exceptions.HTTPException] 。例如想要用一个页面未找到异常来终止请求，你可以调用 abort(404) 。 | 参数: | **code** – the HTTP error code. | |-----|-----| flask.redirect(*location*, *code=302*) Return a response object (a WSGI application) that, if called,redirects the client to the target location. Supported codes are 301,302, 303, 305, and 307. 300 is not supported because it's not a realredirect and 304 because it's the answer for a request with a requestwith defined If-Modified-Since headers. 0.6 新版功能: The location can now be a unicode string that is encoded usingthe iri_to_uri() function. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>location</strong> – the location the response should redirect to.</li><li><strong>code</strong> – the redirect status code. defaults to 302.</li></ul></td></tr></tbody></table> flask.make_response(**args*) Sometimes it is necessary to set additional headers in a view. Becauseviews do not have to return response objects but can return a value thatis converted into a response object by Flask itself, it becomes tricky toadd headers to it. This function can be called instead of using a returnand you will get a response object which you can use to attach headers. If view looked like this and you want to add a new header: ~~~ def index(): return render_template('index.html', foo=42) ~~~ You can now do something like this: ~~~ def index(): response = make_response(render_template('index.html', foo=42)) response.headers['X-Parachutes'] = 'parachutes are cool' return response ~~~ This function accepts the very same arguments you can return from aview function. This for example creates a response with a 404 errorcode: ~~~ response = make_response(render_template('not_found.html'), 404) ~~~ The other use case of this function is to force the return value of aview function into a response which is helpful with viewdecorators: ~~~ response = make_response(view_function()) response.headers['X-Parachutes'] = 'parachutes are cool' ~~~ Internally this function does the following things: - if no arguments are passed, it creates a new response argument - if one argument is passed, [flask.Flask.make_response()](# "flask.Flask.make_response")is invoked with it. - if more than one argument is passed, the arguments are passedto the [flask.Flask.make_response()](# "flask.Flask.make_response") function as tuple. 0.6 新版功能. flask.send_file(*filename_or_fp*, *mimetype=None*, *as_attachment=False*, *attachment_filename=None*, *add_etags=True*, *cache_timeout=None*, *conditional=False*) Sends the contents of a file to the client. This will use themost efficient method available and configured. By default it willtry to use the WSGI server's file_wrapper support. Alternativelyyou can set the application's [use_x_sendfile](# "flask.Flask.use_x_sendfile") attributeto True to directly emit an X-Sendfile header. This howeverrequires support of the underlying webserver for X-Sendfile. By default it will try to guess the mimetype for you, but you canalso explicitly provide one. For extra security you probably wantto send certain files as attachment (HTML for instance). The mimetypeguessing requires a filename or an attachment_filename to beprovided. Please never pass filenames to this function from user sources withoutchecking them first. Something like this is usually sufficient toavoid security problems: ~~~ if '..' in filename or filename.startswith('/'): abort(404) ~~~ 0.2 新版功能. 0.5 新版功能: The add_etags, cache_timeout and conditional parameters wereadded. The default behavior is now to attach etags. 在 0.7 版更改: mimetype guessing and etag support for file objects wasdeprecated because it was unreliable. Pass a filename if you areable to, otherwise attach an etag yourself. This functionalitywill be removed in Flask 1.0 在 0.9 版更改: cache_timeout pulls its default from application config, when None. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>filename_or_fp</strong> – the filename of the file to send. This isrelative to the <tt class="xref py py-attr docutils literal"><span class="pre">root_path</span></tt> if arelative path is specified.Alternatively a file object might be providedin which case <cite>X-Sendfile</cite> might not work andfall back to the traditional method. Make surethat the file pointer is positioned at the startof data to send before calling <a class="reference internal" href="#flask.send_file" title="flask.send_file"><tt class="xref py py-func docutils literal"><span class="pre">send_file()</span></tt></a>.</li><li><strong>mimetype</strong> – the mimetype of the file if provided, otherwiseauto detection happens.</li><li><strong>as_attachment</strong> – set to <cite>True</cite> if you want to send this file witha <tt class="docutils literal"><span class="pre">Content-Disposition:</span> <span class="pre">attachment</span></tt> header.</li><li><strong>attachment_filename</strong> – the filename for the attachment if itdiffers from the file's filename.</li><li><strong>add_etags</strong> – set to <cite>False</cite> to disable attaching of etags.</li><li><strong>conditional</strong> – set to <cite>True</cite> to enable conditional responses.</li><li><strong>cache_timeout</strong> – the timeout in seconds for the headers. When <cite>None</cite>(default), this value is set by<a class="reference internal" href="#flask.Flask.get_send_file_max_age" title="flask.Flask.get_send_file_max_age"><tt class="xref py py-meth docutils literal"><span class="pre">get_send_file_max_age()</span></tt></a> of<a class="reference internal" href="#flask.current_app" title="flask.current_app"><tt class="xref py py-data docutils literal"><span class="pre">current_app</span></tt></a>.</li></ul></td></tr></tbody></table> flask.send_from_directory(*directory*, *filename*, ***options*) Send a file from a given directory with [send_file()](# "flask.send_file"). Thisis a secure way to quickly expose static files from an upload folderor something similar. Example usage: ~~~ @app.route('/uploads/<path:filename>') def download_file(filename): return send_from_directory(app.config['UPLOAD_FOLDER'], filename, as_attachment=True) ~~~ Sending files and Performance It is strongly recommended to activate either X-Sendfile support inyour webserver or (if no authentication happens) to tell the webserverto serve files for the given path on its own without calling into theweb application for improved performance. 0.5 新版功能. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>directory</strong> – the directory where all the files are stored.</li><li><strong>filename</strong> – the filename relative to that directory todownload.</li><li><strong>options</strong> – optional keyword arguments that are directlyforwarded to <a class="reference internal" href="#flask.send_file" title="flask.send_file"><tt class="xref py py-func docutils literal"><span class="pre">send_file()</span></tt></a>.</li></ul></td></tr></tbody></table> flask.safe_join(*directory*, *filename*) Safely join directory and filename. Example usage: ~~~ @app.route('/wiki/<path:filename>') def wiki_page(filename): filename = safe_join(app.config['WIKI_FOLDER'], filename) with open(filename, 'rb') as fd: content = fd.read() # Read and process the file content... ~~~ <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first simple"><li><strong>directory</strong> – the base directory.</li><li><strong>filename</strong> – the untrusted filename relative to that directory.</li></ul></td></tr><tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><p class="first last"><tt class="xref py py-class docutils literal"><span class="pre">NotFound</span></tt> if the resulting pathwould fall out of <cite>directory</cite>.</p></td></tr></tbody></table> flask.escape(*s*) → markup Convert the characters &, <, >, ‘, and ” in string s to HTML-safesequences. Use this if you need to display text that might containsuch characters in HTML. Marks return value as markup string. *class *flask.Markup Marks a string as being safe for inclusion in HTML/XML output withoutneeding to be escaped. This implements the __html__ interface a coupleof frameworks and web applications use. [Markup](# "flask.Markup") is a directsubclass of unicode and provides all the methods of unicode just thatit escapes arguments passed and always returns Markup. The escape function returns markup objects so that double escaping can'thappen. The constructor of the [Markup](# "flask.Markup") class can be used for threedifferent things: When passed an unicode object it's assumed to be safe,when passed an object with an HTML representation (has an __html__method) that representation is used, otherwise the object passed isconverted into a unicode string and then assumed to be safe: ~~~ >>> Markup("Hello <em>World</em>!") Markup(u'Hello <em>World</em>!') >>> class Foo(object): ... def __html__(self): ... return '<a href="#">foo</a>' ... >>> Markup(Foo()) Markup(u'<a href="#">foo</a>') ~~~ If you want object passed being always treated as unsafe you can use the[escape()](# "flask.escape") classmethod to create a [Markup](# "flask.Markup") object: ~~~ >>> Markup.escape("Hello <em>World</em>!") Markup(u'Hello &lt;em&gt;World&lt;/em&gt;!') ~~~ Operations on a markup string are markup aware which means that allarguments are passed through the [escape()](# "flask.escape") function: ~~~ >>> em = Markup("<em>%s</em>") >>> em % "foo & bar" Markup(u'<em>foo &amp; bar</em>') >>> strong = Markup("<strong>%(text)s</strong>") >>> strong % {'text': '<blink>hacker here</blink>'} Markup(u'<strong>&lt;blink&gt;hacker here&lt;/blink&gt;</strong>') >>> Markup("<em>Hello</em> ") + "<foo>" Markup(u'<em>Hello</em> &lt;foo&gt;') ~~~ *classmethod *escape(*s*) Escape the string. Works like [escape()](# "flask.escape") with the differencethat for subclasses of [Markup](# "flask.Markup") this function would return thecorrect subclass. striptags() Unescape markup into an text_type string and strip all tags. Thisalso resolves known HTML4 and XHTML entities. Whitespace isnormalized to one: ~~~ >>> Markup("Main &raquo; <em>About</em>").striptags() u'Main \xbb About' ~~~ unescape() Unescape markup again into an text_type string. This also resolvesknown HTML4 and XHTML entities: ~~~ >>> Markup("Main &raquo; <em>About</em>").unescape() u'Main \xbb <em>About</em>' ~~~ ### 消息闪现 flask.flash(*message*, *category='message'*) Flashes a message to the next request. In order to remove theflashed message from the session and to display it to the user,the template has to call [get_flashed_messages()](# "flask.get_flashed_messages"). 在 0.3 版更改: category parameter added. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>message</strong> – the message to be flashed.</li><li><strong>category</strong> – the category for the message. The following valuesare recommended: <tt class="docutils literal"><span class="pre">'message'</span></tt> for any kind of message,<tt class="docutils literal"><span class="pre">'error'</span></tt> for errors, <tt class="docutils literal"><span class="pre">'info'</span></tt> for informationmessages and <tt class="docutils literal"><span class="pre">'warning'</span></tt> for warnings. However anykind of string can be used as category.</li></ul></td></tr></tbody></table> flask.get_flashed_messages(*with_categories=False*, *category_filter=*[]) Pulls all flashed messages from the session and returns them.Further calls in the same request to the function will returnthe same messages. By default just the messages are returned,but when with_categories is set to True, the return value willbe a list of tuples in the form (category,message) instead. Filter the flashed messages to one or more categories by providing thosecategories in category_filter. This allows rendering categories inseparate html blocks. The with_categories and category_filterarguments are distinct: - with_categories controls whether categories are returned with messagetext (True gives a tuple, where False gives just the message text). - category_filter filters the messages down to only those matching theprovided categories. See [*消息闪现*](#) for examples. 在 0.3 版更改: with_categories parameter added. 在 0.9 版更改: category_filter parameter added. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>with_categories</strong> – set to <cite>True</cite> to also receive categories.</li><li><strong>category_filter</strong> – whitelist of categories to limit return values</li></ul></td></tr></tbody></table> ### JSON 支持 Flask 使用 simplejson 来实现JSON。自从 simplejson 既在标准库中提供也在Flask 的拓展中提供。Flask将首先尝试自带的simplejson，如果失败了就使用标准库中的json模块。除此之外，为了更容易定制它还会委托访问当前应用的JSON的编码器和解码器。 所以首先不要这样用： > try:import simplejson as jsonexcept ImportError:import json 你可以这样 ~~~ from flask import json ~~~ For usage examples, read the [json](http://docs.python.org/dev/library/json.html#module-json "(在 Python v3.5)") [http://docs.python.org/dev/library/json.html#module-json] documentation.关于更多的用法，请阅读标准库中的 [json](http://docs.python.org/dev/library/json.html#module-json "(在 Python v3.5)") [http://docs.python.org/dev/library/json.html#module-json] 文档。下面的拓展已经默认被集成到了标准库中JSON模块里： 1. datetime 对象被序列化为 [**RFC 822**](http://tools.ietf.org/html/rfc822.html) [http://tools.ietf.org/html/rfc822.html] 字符串。 1. 任何带有 __html__ 方法(比如 [Markup](# "flask.Markup"))将在序列化的时候调用这个方法然后返回的字符串将会被序列化为字符串。 这个 htmlsafe_dumps() 方法也能在 Jinja2 的过滤器中使用，名字为|tojson 。请注意在 script 标签内部的内容将不会被转义，所以如果你想在script 内部使用的话请确保它是不可用的通过 |safe 来转义，除非你正在使用 Flask 0.10，如下： ~~~ <script type=text/javascript> doSomethingWith({{ user.username|tojson|safe }}); </script> ~~~ flask.json.jsonify(**args*, ***kwargs*) Creates a [Response](# "flask.Response") with the JSON representation ofthe given arguments with an application/json mimetype. The argumentsto this function are the same as to the [dict](http://docs.python.org/dev/library/stdtypes.html#dict "(在 Python v3.5)") [http://docs.python.org/dev/library/stdtypes.html#dict] constructor. Example usage: ~~~ from flask import jsonify @app.route('/_get_current_user') def get_current_user(): return jsonify(username=g.user.username, email=g.user.email, id=g.user.id) ~~~ This will send a JSON response like this to the browser: ~~~ { "username": "admin", "email": "admin@localhost", "id": 42 } ~~~ For security reasons only objects are supported toplevel. For moreinformation about this, have a look at [*JSON 安全*](#). This function's response will be pretty printed if it was not requestedwith X-Requested-With:XMLHttpRequest to simplify debugging unlessthe JSONIFY_PRETTYPRINT_REGULAR config parameter is set to false. 0.2 新版功能. flask.json.dumps(*obj*, ***kwargs*) Serialize obj to a JSON formatted str by using the application'sconfigured encoder ([json_encoder](# "flask.Flask.json_encoder")) if there is anapplication on the stack. This function can return unicode strings or ascii-only bytestrings bydefault which coerce into unicode strings automatically. That behavior bydefault is controlled by the JSON_AS_ASCII configuration variableand can be overriden by the simplejson ensure_ascii parameter. flask.json.dump(*obj*, *fp*, ***kwargs*) Like [dumps()](# "flask.json.dumps") but writes into a file object. flask.json.loads(*s*, ***kwargs*) Unserialize a JSON object from a string s by using the application'sconfigured decoder ([json_decoder](# "flask.Flask.json_decoder")) if there is anapplication on the stack. flask.json.load(*fp*, ***kwargs*) Like [loads()](# "flask.json.loads") but reads from a file object. *class *flask.json.JSONEncoder(*skipkeys=False*, *ensure_ascii=True*, *check_circular=True*, *allow_nan=True*, *sort_keys=False*, *indent=None*, *separators=None*, *encoding='utf-8'*, *default=None*, *use_decimal=True*, *namedtuple_as_object=True*, *tuple_as_array=True*) The default Flask JSON encoder. This one extends the default simplejsonencoder by also supporting datetime objects, UUID as well asMarkup objects which are serialized as RFC 822 datetime strings (sameas the HTTP date format). In order to support more data types override the[default()](# "flask.json.JSONEncoder.default") method. default(*o*) Implement this method in a subclass such that it returns aserializable object for o, or calls the base implementation (toraise a TypeError). For example, to support arbitrary iterators, you could implementdefault like this: ~~~ def default(self, o): try: iterable = iter(o) except TypeError: pass else: return list(iterable) return JSONEncoder.default(self, o) ~~~ *class *flask.json.JSONDecoder(*encoding=None*, *object_hook=None*, *parse_float=None*, *parse_int=None*, *parse_constant=None*, *strict=True*, *object_pairs_hook=None*) The default JSON decoder. This one does not change the behavior fromthe default simplejson encoder. Consult the [json](http://docs.python.org/dev/library/json.html#module-json "(在 Python v3.5)") [http://docs.python.org/dev/library/json.html#module-json] documentationfor more information. This decoder is not only used for the loadfunctions of this module but also [Request](# "flask.Request"). ### 模板渲染 flask.render_template(*template_name_or_list*, ***context*) Renders a template from the template folder with the givencontext. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>template_name_or_list</strong> – the name of the template to berendered, or an iterable with template namesthe first one existing will be rendered</li><li><strong>context</strong> – the variables that should be available in thecontext of the template.</li></ul></td></tr></tbody></table> flask.render_template_string(*source*, ***context*) Renders a template from the given template source stringwith the given context. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>source</strong> – the sourcecode of the template to berendered</li><li><strong>context</strong> – the variables that should be available in thecontext of the template.</li></ul></td></tr></tbody></table> flask.get_template_attribute(*template_name*, *attribute*) Loads a macro (or variable) a template exports. This can be used toinvoke a macro from within Python code. If you for example have atemplate named _cider.html with the following contents: ~~~ {% macro hello(name) %}Hello {{ name }}!{% endmacro %} ~~~ You can access this from Python code like this: ~~~ hello = get_template_attribute('_cider.html', 'hello') return hello('World') ~~~ 0.2 新版功能. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>template_name</strong> – the name of the template</li><li><strong>attribute</strong> – the name of the variable of macro to access</li></ul></td></tr></tbody></table> ### 配置 *class *flask.Config(*root_path*, *defaults=None*) Works exactly like a dict but provides ways to fill it from filesor special dictionaries. There are two common patterns to populate theconfig. Either you can fill the config from a config file: ~~~ app.config.from_pyfile('yourconfig.cfg') ~~~ Or alternatively you can define the configuration options in themodule that calls [from_object()](# "flask.Config.from_object") or provide an import path toa module that should be loaded. It is also possible to tell it touse the same module and with that provide the configuration valuesjust before the call: ~~~ DEBUG = True SECRET_KEY = 'development key' app.config.from_object(__name__) ~~~ In both cases (loading from any Python file or loading from modules),only uppercase keys are added to the config. This makes it possible to uselowercase values in the config file for temporary values that are not addedto the config or to define the config keys in the same file that implementsthe application. Probably the most interesting way to load configurations is from anenvironment variable pointing to a file: ~~~ app.config.from_envvar('YOURAPPLICATION_SETTINGS') ~~~ In this case before launching the application you have to set thisenvironment variable to the file you want to use. On Linux and OS Xuse the export statement: ~~~ export YOURAPPLICATION_SETTINGS='/path/to/config/file' ~~~ On windows use set instead. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>root_path</strong> – path to which files are read relative from. When theconfig object is created by the application, this isthe application's <tt class="xref py py-attr docutils literal"><span class="pre">root_path</span></tt>.</li><li><strong>defaults</strong> – an optional dictionary of default values</li></ul></td></tr></tbody></table> from_envvar(*variable_name*, *silent=False*) Loads a configuration from an environment variable pointing toa configuration file. This is basically just a shortcut with nicererror messages for this line of code: ~~~ app.config.from_pyfile(os.environ['YOURAPPLICATION_SETTINGS']) ~~~ <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first simple"><li><strong>variable_name</strong> – name of the environment variable</li><li><strong>silent</strong> – set to <cite>True</cite> if you want silent failure for missingfiles.</li></ul></td></tr><tr class="field-even field"><th class="field-name">返回:</th><td class="field-body"><p class="first last">bool. <cite>True</cite> if able to load config, <cite>False</cite> otherwise.</p></td></tr></tbody></table> from_object(*obj*) Updates the values from the given object. An object can be of oneof the following two types: - a string: in this case the object with that name will be imported - an actual object reference: that object is used directly Objects are usually either modules or classes. Just the uppercase variables in that object are stored in the config.Example usage: ~~~ app.config.from_object('yourapplication.default_config') from yourapplication import default_config app.config.from_object(default_config) ~~~ You should not use this function to load the actual configuration butrather configuration defaults. The actual config should be loadedwith [from_pyfile()](# "flask.Config.from_pyfile") and ideally from a location not within thepackage because the package might be installed system wide. | 参数: | **obj** – an import name or object | |-----|-----| from_pyfile(*filename*, *silent=False*) Updates the values in the config from a Python file. This functionbehaves as if the file was imported as module with the[from_object()](# "flask.Config.from_object") function. <table class="docutils field-list" frame="void" rules="none"><col class="field-name"/><col class="field-body"/><tbody valign="top"><tr class="field-odd field"><th class="field-name">参数:</th><td class="field-body"><ul class="first last simple"><li><strong>filename</strong> – the filename of the config. This can either be anabsolute filename or a filename relative to theroot path.</li><li><strong>silent</strong> – set to <cite>True</cite> if you want silent failure for missingfiles.</li></ul></td></tr></tbody></table> 0.7 新版功能: silent parameter. ### 扩展 flask.ext 这个模块重定向导入模块到 Flask 扩展。它在 0.8 中被加入，作为导入 Flask扩展的权威方式，并使得我们在发布扩展时能有更大的灵活性。 如果你想使用名为 “Flask-Foo” 的扩展，你应按照下述从 [ext](# "flask.flask.ext")导入: ~~~ from flask.ext import foo ~~~ 0.8 新版功能. ### 流的辅助函数 flask.stream_with_context(*generator_or_function*) Request contexts disappear when the response is started on the server.This is done for efficiency reasons and to make it less likely to encountermemory leaks with badly written WSGI middlewares. The downside is that ifyou are using streamed responses, the generator cannot access request boundinformation any more. This function however can help you keep the context around for longer: ~~~ from flask import stream_with_context, request, Response @app.route('/stream') def streamed_response(): @stream_with_context def generate(): yield 'Hello ' yield request.args['name'] yield '!' return Response(generate()) ~~~ Alternatively it can also be used around a specific generator: ~~~ from flask import stream_with_context, request, Response @app.route('/stream') def streamed_response(): def generate(): yield 'Hello ' yield request.args['name'] yield '!' return Response(stream_with_context(generate())) ~~~ 0.9 新版功能. ### 有用的内构件 *class *flask.ctx.RequestContext(*app*, *environ*, *request=None*) The request context contains all request relevant information. It iscreated at the beginning of the request and pushed to the_request_ctx_stack and removed at the end of it. It will create theURL adapter and request object for the WSGI environment provided. Do not attempt to use this class directly, instead use[test_request_context()](# "flask.Flask.test_request_context") and[request_context()](# "flask.Flask.request_context") to create this object. When the request context is popped, it will evaluate all thefunctions registered on the application for teardown execution([teardown_request()](# "flask.Flask.teardown_request")). The request context is automatically popped at the end of the requestfor you. In debug mode the request context is kept around ifexceptions happen so that interactive debuggers have a chance tointrospect the data. With 0.4 this can also be forced for requeststhat did not fail and outside of DEBUG mode. By setting'flask._preserve_context' to True on the WSGI environment thecontext will not pop itself at the end of the request. This is used bythe [test_client()](# "flask.Flask.test_client") for example to implement thedeferred cleanup functionality. You might find this helpful for unittests where you need theinformation from the context local around for a little longer. Makesure to properly pop() the stack yourself inthat situation, otherwise your unittests will leak memory. copy() Creates a copy of this request context with the same request object.This can be used to move a request context to a different greenlet.Because the actual request object is the same this cannot be used tomove a request context to a different thread unless access to therequest object is locked. 0.10 新版功能. match_request() Can be overridden by a subclass to hook into the matchingof the request. pop(*exc=None*) Pops the request context and unbinds it by doing that. This willalso trigger the execution of functions registered by the[teardown_request()](# "flask.Flask.teardown_request") decorator. 在 0.9 版更改: Added the exc argument. push() Binds the request context to the current context. flask._request_ctx_stack Flask 中使用的所有的上下文局部对象，都由内部的[LocalStack](http://werkzeug.pocoo.org/docs/local/#werkzeug.local.LocalStack "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/local/#werkzeug.local.LocalStack] 实现。这是一个带文档的实例，并且可以在扩展和应用的代码中使用，但一般来说是不推荐这样使用的。 下面的属性在栈的每层上都存在: app活动的 Flask 应用url_adapter用于匹配请求的 URL 适配器request当前的请求对象session当前的会话对象g拥有 [flask.g](# "flask.g") 对象上全部属性的对象flashes闪现消息的内部缓存 用法示例: ~~~ from flask import _request_ctx_stack def get_session(): ctx = _request_ctx_stack.top if ctx is not None: return ctx.session ~~~ *class *flask.ctx.AppContext(*app*) The application context binds an application object implicitlyto the current thread or greenlet, similar to how theRequestContext binds request information. The applicationcontext is also implicitly created if a request context is createdbut the application is not on top of the individual applicationcontext. pop(*exc=None*) Pops the app context. push() Binds the app context to the current context. flask._app_ctx_stack 类似请求上下文，但是只跟应用绑定。主要为扩展提供数据存储。 0.9 新版功能. *class *flask.blueprints.BlueprintSetupState(*blueprint*, *app*, *options*, *first_registration*) Temporary holder object for registering a blueprint with theapplication. An instance of this class is created by the[make_setup_state()](# "flask.Blueprint.make_setup_state") method and later passedto all register callback functions. add_url_rule(*rule*, *endpoint=None*, *view_func=None*, ***options*) A helper method to register a rule (and optionally a view function)to the application. The endpoint is automatically prefixed with theblueprint's name. app* = None* a reference to the current application blueprint* = None* a reference to the blueprint that created this setup state. first_registration* = None* as blueprints can be registered multiple times with theapplication and not everything wants to be registeredmultiple times on it, this attribute can be used to figureout if the blueprint was registered in the past already. options* = None* a dictionary with all options that were passed to the[register_blueprint()](# "flask.Flask.register_blueprint") method. subdomain* = None* The subdomain that the blueprint should be active for, Noneotherwise. url_defaults* = None* A dictionary with URL defaults that is added to each and everyURL that was defined with the blueprint. url_prefix* = None* The prefix that should be used for all URLs defined on theblueprint. ### 信号 0.6 新版功能. flask.signals_available 当信号系统可用时为 True ，即在 [blinker](http://pypi.python.org/pypi/blinker) [http://pypi.python.org/pypi/blinker] 已经被安装的情况下。 flask.template_rendered 当一个模板成功渲染的时候，这个信号会发出。这个信号带着一个模板实例template 和为一个字典的上下文（叫 context ）两个参数被调用。 flask.request_started 这个信号在处建立请求上下文之外的任何请求处理开始前发送。因为请求上下文这个信号在任何对请求的处理前发送，但是正好是在请求的上下文被建立的时候。因为请求上下文已经被约束了，用户可以使用 [request](# "flask.request") 之类的标准全局代理访问请求对象。 flask.request_finished 这个信号恰好在请求发送给客户端之前发送。它传递名为 response 的将被发送的响应。 flask.got_request_exception 这个信号在请求处理中抛出异常时发送。它在标准异常处理生效 *之前* ，甚至是在不会处理异常的调试模式下也是如此。这个异常会被将作为一个 exception传递到用户那。 flask.request_tearing_down 这个信号在请求销毁时发送。它总会被调用，即使发生异常。在这种清况下，造成teardown的异常将会通过一个叫 exc 的关键字参数传递出来。 在 0.9 版更改: 添加了 exc 参数 flask.appcontext_tearing_down 这个信号在应用上下文销毁时发送。它总会被调用，即使发生异常。在这种清况下，造成teardown的异常将会通过一个叫 exc 的关键字参数传递出来。发送者是application对象。 flask.appcontext_pushed 当应用上下文被压入栈后会发送这个信号。发送者是application对象 0.10 新版功能. flask.appcontext_popped 当应用上下文出栈后会发送这个信号。发送者是application对象。这常常与[appcontext_tearing_down](# "flask.appcontext_tearing_down") 这个信号一致。 0.10 新版功能. flask.message_flashed This signal is sent when the application is flashing a message.The messages is sent as message keyword argument and the当闪现一个消息时会发送这个信号。消息的内容将以 message 关键字参数发送，而消息的种类则是 category 关键字参数。 0.10 新版功能. *class *flask.signals.Namespace [blinker.base.Namespace](http://discorporate.us/projects/Blinker/docs/1.1/api.html#blinker.base.Namespace "(在 Blinker v1.1)") [http://discorporate.us/projects/Blinker/docs/1.1/api.html#blinker.base.Namespace] 的别名，如果 blinker 可用的话。否则，是一个发送伪信号的伪造的类。这个类对想提供与 Flask 相同的备用系统的Flask扩展有用。 signal(*name*, *doc=None*) 在此命名空间中创建一个新信号，如果 blinker 可用的话。否则返回一个带有不做任何事的发送方法，任何操作都会（包括连接）报错为[RuntimeError](http://docs.python.org/dev/library/exceptions.html#RuntimeError "(在 Python v3.5)") [http://docs.python.org/dev/library/exceptions.html#RuntimeError] 的伪信号。 ### 基于类的视图 0.7 新版功能. *class *flask.views.View Alternative way to use view functions. A subclass has to implementdispatch_request() which is called with the view arguments fromthe URL routing system. If methods is provided the methodsdo not have to be passed to the [add_url_rule()](# "flask.Flask.add_url_rule")method explicitly: ~~~ class MyView(View): methods = ['GET'] def dispatch_request(self, name): return 'Hello %s!' % name app.add_url_rule('/hello/<name>', view_func=MyView.as_view('myview')) ~~~ When you want to decorate a pluggable view you will have to either do thatwhen the view function is created (by wrapping the return value ofas_view()) or you can use the decorators attribute: ~~~ class SecretView(View): methods = ['GET'] decorators = [superuser_required] def dispatch_request(self): ... ~~~ The decorators stored in the decorators list are applied one after anotherwhen the view function is created. Note that you can *not* use the classbased decorators since those would decorate the view class and not thegenerated view function! *classmethod *as_view(*name*, **class_args*, ***class_kwargs*) Converts the class into an actual view function that can be usedwith the routing system. Internally this generates a function on thefly which will instantiate the View on each request and callthe dispatch_request() method on it. The arguments passed to as_view() are forwarded to theconstructor of the class. decorators* = []* The canonical way to decorate class-based views is to decorate thereturn value of as_view(). However since this moves parts of thelogic from the class declaration to the place where it's hookedinto the routing system. You can place one or more decorators in this list and whenever theview function is created the result is automatically decorated. 0.8 新版功能. dispatch_request() Subclasses have to override this method to implement theactual view function code. This method is called with allthe arguments from the URL rule. methods* = None* A for which methods this pluggable view can handle. *class *flask.views.MethodView Like a regular class-based view but that dispatches requests toparticular methods. For instance if you implement a method calledget() it means you will response to 'GET' requests andthe dispatch_request() implementation will automaticallyforward your request to that. Also options is set for youautomatically: ~~~ class CounterAPI(MethodView): def get(self): return session.get('counter', 0) def post(self): session['counter'] = session.get('counter', 0) + 1 return 'OK' app.add_url_rule('/counter', view_func=CounterAPI.as_view('counter')) ~~~ ### URL 路由注册 在路由系统中定义规则可以的方法可以概括为三种: 1. 使用 [flask.Flask.route()](# "flask.Flask.route") 装饰器 1. 使用 [flask.Flask.add_url_rule()](# "flask.Flask.add_url_rule") 函数 1. 直接访问暴露为 [flask.Flask.url_map](# "flask.Flask.url_map") 的底层的 Werkzeug 路由系统 路由中的变量部分可以用尖括号指定（ /user/<username>）。默认情况下，URL中的变量部分接受任何不带斜线的字符串，而 <converter:name> 也可以指定不同的转换器。 变量部分以关键字参数传递给视图函数。 下面的转换器是可用的: | string | 接受任何不带斜线的字符串（默认的转换器） | |-----|-----| | int | 接受整数 | | float | 同 int ，但是接受浮点数 | | path | 和默认的相似，但也接受斜线 | 这里是一些例子: ~~~ @app.route('/') def index(): pass @app.route('/<username>') def show_user(username): pass @app.route('/post/<int:post_id>') def show_post(post_id): pass ~~~ 需要注意的一个重要细节是 Flask 处理结尾斜线的方式。你可以应用下面两个规则来保证 URL 的唯一: 1. 如果规则以斜线结尾，当用户以不带斜线的形式请求，用户被自动重定向到带有结尾斜线的相同页面。 1. 如果规则结尾没有斜线，当用户以带斜线的形式请求，会抛出一个 404 notfound 。 这与 web 服务器处理静态文件的方式一致。这使得安全地使用相对链接地址成为可能。 你可以为同一个函数定义多个规则。无论如何，他们也要唯一。也可以给定默认值。这里给出一个接受可选页面的 URL 定义: ~~~ @app.route('/users/', defaults={'page': 1}) @app.route('/users/page/<int:page>') def show_users(page): pass ~~~ 这指定了 /users/ 为第一页的 URL ，/users/page/N 为第 N 页的 URL 。 以下是 [route()](# "flask.Flask.route") 和 [add_url_rule()](# "flask.Flask.add_url_rule")接受的参数。两者唯一的区别是，带有路由参数的视图函数用装饰器定义，而不是view_func 参数。 | rule | URL 规则的字符串 | |-----|-----| | endpoint | 注册的 URL 规则的末端。如果没有显式地规定，Flask 本身假设末端的名称是视图函数的名称，。 | | view_func | 当请求呈递到给定的末端时调用的函数。如果没有提供，可以在用在 [view_functions](# "flask.Flask.view_functions") 字典中以末端作为键名存储，来在之后设定函数。 | | defaults | 规则默认值的字典。上面的示例介绍了默认值如何工作。 | | subdomain | 当使用子域名匹配的时候，为子域名设定规则。如果没有给定，假定为默认的子域名。 | | **options | 这些选项会被推送给底层的 [Rule](http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule "(在 Werkzeug v0.10)") [http://werkzeug.pocoo.org/docs/routing/#werkzeug.routing.Rule]对象。一个 Werkzeug 的变化是 method 选项的处理。methods是这个规则被限定的方法列表（ GET ， POST 等等）。默认情况下，规则只监听 GET （也隐式地监听 HEAD ）。从 Flask0.6 开始，OPTIONS 也被隐式地加入，并且做标准的请求处理。它们需要作为关键字参数来给定。 | ### 视图函数选项 对内部使用，视图函数可以有一些属性，附加到视图函数通常没有控制权的自定义的行为。下面的可选属性覆盖 [add_url_rule()](# "flask.Flask.add_url_rule") 的默认值或一般行为: - __name__: 函数的名称默认用于末端。如果显式地提供末端，这个值会使用。此外，它默认以蓝图的名称作为前缀，并且不能从函数本身自定义。 - methods: 如果没有在添加 URL 规则时提供 methods 参数。 Flask 会在视图函数对象上寻找是否存在 methods 属性。如果存在，它会从上面拉取方法的信息。 - provide_automatic_options: 如果设置了这个属性， Flask 会强制禁用或启用 HTTP OPTIONS 响应的自动实现。这对于对单个视图自定义 OPTIONS响应而使用装饰器的情况下是有用的。 - required_methods: 如果这个属性被设置了， 当注册一个 URL 规则的时候，Flask 将总是会添加这些 methods 即使 methods 参数在 route() 调用的时候被显式的覆盖了。 完整的例子: ~~~ def index(): if request.method == 'OPTIONS': # custom options handling here ... return 'Hello World!' index.provide_automatic_options = False index.methods = ['GET', 'OPTIONS'] app.add_url_rule('/', index) ~~~ 0.8 新版功能: 加入了 provide_automatic_options 功能。 © 版权所有 2013, Armin Ronacher.