Twig: in_array or similar possible within if statement?
Solution 1:
You just have to change the second line of your second code-block from
{% if myVar is in_array(array_keys(someOtherArray)) %}
to
{% if myVar in someOtherArray|keys %}
in is the containment-operator and keys a filter that returns an arrays keys.
Solution 2:
Just to clear some things up here. The answer that was accepted does not do the same as PHP in_array.
To do the same as PHP in_array use following expression:
{% if myVar in myArray %}
If you want to negate this you should use this:
{% if myVar not in myArray %}