twig variable is defined code example

Example 1: if variable is defined twig

{# 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 %}

Example 2: twig variable is defined

{% if varname is defined %}
	Variable exists.
{% endif %}

Example 3: twig variable is not defined

{% if not (varname is defined) %}
	Variable does not exist.
{% endif %}