comments framework uses uncached content types

[Craig de Stigter]

We found our list views were doing too many database queries for content types, even with caching turned on.

Turns out the comments framework is to blame, for using the uncached method ContentType.objects.get(...)

This one-liner fixes it:

--- a/django/contrib/comments/templatetags/comments.py
+++ b/django/contrib/comments/templatetags/comments.py
@@ -49,7 +49,7 @@ class BaseCommentNode(template.Node):
     def lookup_content_type(token, tagname):
         try:
             app, model = token.split('.')
-            return ContentType.objects.get(app_label=app, model=model)
+            return ContentType.objects.get_by_natural_key(app, model)
         except ValueError:
             raise template.TemplateSyntaxError("Third argument in %r must be in the format 'app.model'" % tagname)
         except ContentType.DoesNotExist:

[Thejaswi Puthraya]

As per a discussion with freakyboy3742 on IRC, this requires a test that makes use of assertNumQueries to show the number of queries did in fact reduce.

[Thejaswi Puthraya]

git patch against the latest checkout

[Julien Phalip]

The patch is looking good but the tests are raising a warning:

UserWarning: A {% csrf_token %} was used in a template, but the context did not provide the value.  This is usually caused by not using RequestContext.

[Julien Phalip]

Also, the tests would be more robust if they asserted precise values instead of using the rather vague "assertLess".

[Thejaswi Puthraya]

patch against the latest git checkout

[Harro]

small remark on the tests. Store the current DEBUG value in the setUp on self and restore it in tearDown, now you assume it's False when you start the tests.

[Thejaswi Puthraya]

changes as per hvdklauw's latest comments

[Julien Phalip]

Cleaner, more thorough tests

[Preston Holmes]

patch improved with missing import

[Preston Holmes]

Other than a missing model import in the tests (which I fixed in 16042.5), the submitted patch seems to solve the original problem - and demonstrates via tests as requested in previous comments.

[Jannis Leidel]

In [16737]:

Fixed #16042 -- Use the content types caching in the comments contrib app. Thanks, ptone, Julien Phalip and Thejaswi Puthraya.

[Simon Charette]

As #17256 and calls such as

# Force the CT to be cached
ct = ContentType.objects.get_for_model(Article)

in r16737 tests highlight that get_by_natural_key  doesn't actually cache anything.

#17256's currently attached patch make sure get_by_natural_key actually cache cts and remove the needs for get_for_model calls in the tests.