#``defined`` ``defined`` checks if a variable is defined in the current context. This is very useful if you use the ``strict_variables`` option: {# 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 %} When using the ``defined`` test on an expression that uses variables in some method calls, be sure that they are all defined first: {% if var is defined and foo.method(var) is defined %} ... {% endif %}