How do I import the Django DoesNotExist exception?

I'm trying to create a UnitTest to verify that an object has been deleted.

from django.utils import unittest
def test_z_Kallie_can_delete_discussion_response(self):
  ...snip...
  self._driver.get("http://localhost:8000/questions/3/want-a-discussion") 
  self.assertRaises(Answer.DoesNotExist, Answer.objects.get(body__exact = '<p>User can reply to discussion.</p>'))

I keep getting the error:

DoesNotExist: Answer matching query does not exist.

Solution 1:

You can also import ObjectDoesNotExist from django.core.exceptions, if you want a generic, model-independent way to catch the exception:

from django.core.exceptions import ObjectDoesNotExist

try:
    SomeModel.objects.get(pk=1)
except ObjectDoesNotExist:
    print 'Does Not Exist!'

Solution 2:

You don't need to import it - as you've already correctly written, DoesNotExist is a property of the model itself, in this case Answer.

Your problem is that you are calling the get method - which raises the exception - before it is passed to assertRaises. You need to separate the arguments from the callable, as described in the unittest documentation:

self.assertRaises(Answer.DoesNotExist, Answer.objects.get, body__exact='<p>User can reply to discussion.</p>')

or better:

with self.assertRaises(Answer.DoesNotExist):
    Answer.objects.get(body__exact='<p>User can reply to discussion.</p>')

Solution 3:

DoesNotExist is always a property of the model that does not exist. In this case it would be Answer.DoesNotExist.