TWIG: is defined and is not null

Question

quick question I have a var and I want to check if it is defined (to avoid have a bug in the render) and if it is not null (to display something with a Else if null)

{% if var is not null %} works

{% if var is defined %} works

{% if var is not null and is defined %} does not work any idea of the correct syntax?

EDIT the workaround will be:

{% if var is defined %}
    {% if var is not null %}
        {{ var }}
    {% else %}
        blabla
    {% endif %}
{% endif %}

That a lot of code for something simple... ideas how to merge the two IF?

Answer 1

Wrong

{% if var is not null and var is defined %}

This does not work because a variable which is null in twig is defnied, but if you check for null first and it is not defined it will throw an error.

Correct

{% if var is defined and var is not null %}

This will work because we check if it is defined first and will abord when not. Only if the variable is defined we check if it is null.

Answer 2

You need to declare the var in each check so {% if var is defined and var is not null %}.

Answer 3

I have always used the ?? operator to provide a 'default' value when I know a variable might not be defined. So {% if (var is defined and var is not null) %} is equivalent to:

{% if (var ?? null) is not null %}

If you just want to check whether a value that might not be defined is truthy you can do this:

{% if (var ?? null) %}