Twig Components / Methods / defined

defined is a Twig test to check 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 %}

Source: Twig