The default filter returns the passed default value if the value is undefined or empty, otherwise the value of the variable:

{{ var | default('var is not defined') }}

{{ | default('foo item on var is not defined') }}

{{ var['foo'] | default('foo item on var is not defined') }}

{{ '' | default('passed var is empty') }}

When using the default filter on an expression that uses variables in some method calls, be sure to use the default filter whenever a variable can be undefined:

{{ var.method(foo | default('foo')) | default('foo') }}

Using the default filter on a boolean variable might trigger unexpected behaviour, as false is treated as an empty value. Consider using ?? instead:

{% set foo = false %}
{{ foo | default(true) }} {# true #}
{{ foo ?? true }} {# false #}

Read the documentation for the defined and empty tests to learn more about their semantics.


Argument Description Type
default The default value String