raise an exception in jinja if we passed in a variable that is not present in the template

Question

Is there a method for jinja2 to raise an exception when we pass a variable that is not present in the template?

PS: This is different(or opposite) from raising an exception when a variable is present in the template but it is not passed. For this I use "undefined=StrictUndefined"

Answer 1

When you load your jinja2.Environment, set the 'undefined' parameter to 'jinja2.StrictUndefined', e.g.:

env = jinja2.Environment(loader=<someloader>, undefined=jinja2.StrictUndefined)

You can catch and examine the render exception to see what was missing

EDIT It would help if I read your full question. :)

Answer 2

Maybe this could help you https://jinja.palletsprojects.com/en/2.11.x/api/#the-meta-api

>>> from jinja2 import Environment, meta
>>> env = Environment()
>>> ast = env.parse('{% set foo = 42 %}{{ bar + foo }}')
>>> meta.find_undeclared_variables(ast)
set(['bar'])

Answer 3

You can also do that:

from jinja2 import Template, StrictUndefined
Template('name: {{ name }} , city: {{ city }}',undefined=StrictUndefined).render(**{"name":"foo","city":"bar"})