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

In the Environment setup, we had undefined = StrictUndefined, which prevented undefined values from being set to anything. This fixed it:

from jinja2 import Undefined
JINJA2_ENVIRONMENT_OPTIONS = { 'undefined' : Undefined }