php - In Twig, check if a specific key of an array exists

Question

In PHP we can check if a key exists in an array by using the function array_key_exists().

In the Twig templating language we can check if an variable or an object's property exists simply by using an if statement, like this:

{% if app.user %}
do something here
{% else %}
do something else
{% endif %}

But how do we check if a key of an array exists using Twig? I tried {% if array.key %}, but it gives me an error:

Key "key" for array with keys "0, 1, 2, 3...648" does not exist

As one of the primary ways of passing data into a template is using arrays, it seems like there should be some way of doing this. Any thoughts?

Answer 1

Twig example:

{% if array.key is defined %}
  // do something
{% else %}
  // do something else
{% endif %}