In Jinja2, how do you test if a variable is undefined?

Question

Converting from Django, I\'m used to doing something like this:

{% if not var1 %} {% endif %}

and having it work if I didn\'t put var1 into

Answer 1

{% if variable is defined %} is true if the variable is None.

Since not is None is not allowed, that means that

{% if variable != None %}

is really your only option.