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 %} works to check if something is undefined.

You can get away with using {% if not var1 %} if you default your variables to False eg

class MainHandler(BaseHandler):
    def get(self):
        var1 = self.request.get('var1', False)