# `defined` `defined` checks if a variable is defined in the current context. This is veryuseful if you use the `strict_variables` option: <table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre> 1 2 3 4 5 6 7 8 9 10 11 12 13</pre></div></td><td class="code"><div class="highlight"><pre>{# defined works with variable names #} {% if foo is defined %} ... {% endif %} {# and attributes on variables names #} {% if foo.bar is defined %} ... {% endif %} {% if foo['bar'] is defined %} ... {% endif %} </pre></div></td></tr></table> When using the `defined` test on an expression that uses variables in somemethod calls, be sure that they are all defined first: <table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre>1 2 3</pre></div></td><td class="code"><div class="highlight"><pre>{% if var is defined and foo.method(var) is defined %} ... {% endif %} </pre></div></td></tr></table>