django/contrib/contenttypes/tests.py

   1 """
   2 Make sure that the content type cache (see ContentTypeManager) works correctly.
   3 Lookups for a particular content type -- by model or by ID -- should hit the
   4 database only on the first lookup.
   5
   6 First, let's make sure we're dealing with a blank slate (and that DEBUG is on so
   7 that queries get logged)::
   8
   9     >>> from django.conf import settings
  10     >>> settings.DEBUG = True
  11
  12     >>> from django.contrib.contenttypes.models import ContentType
  13     >>> ContentType.objects.clear_cache()
  14
  15     >>> from django import db
  16     >>> db.reset_queries()
  17
  18 At this point, a lookup for a ContentType should hit the DB::
  19
  20     >>> ContentType.objects.get_for_model(ContentType)
  21     <ContentType: content type>
  22
  23     >>> len(db.connection.queries)
  24     1
  25
  26 A second hit, though, won't hit the DB, nor will a lookup by ID::
  27
  28     >>> ct = ContentType.objects.get_for_model(ContentType)
  29     >>> len(db.connection.queries)
  30     1
  31     >>> ContentType.objects.get_for_id(ct.id)
  32     <ContentType: content type>
  33     >>> len(db.connection.queries)
  34     1
  35
  36 Once we clear the cache, another lookup will again hit the DB::
  37
  38     >>> ContentType.objects.clear_cache()
  39     >>> ContentType.objects.get_for_model(ContentType)
  40     <ContentType: content type>
  41     >>> len(db.connection.queries)
  42     2
  43
  44 Don't forget to reset DEBUG!
  45
  46     >>> settings.DEBUG = False
  47 """