anchor.diff:  Querying
   ~~~~~~~~
   
  -At this momment, no custom lookups are implemented for json field and PostgreSQL 9.3
  -(the current stable release) does not have much operators for json field. On PostgreSQL 9.4
  -json type is improved a lot and much other operators are added.
  -
  -.Simple query using *extra*
  +At this momment with postgresql 9.3 as last stable version it has very limited set
  +of native operators for json type (with 9.4 much other operators will added).
  +
  +If you are using django 1.7, you can use index or key lookup for filtering:
  +
  +[source, pycon]
  +----
  +>>> Something.object.bulk_create([
  +...     Something(data={"name": "foo"}),
  +...     Something(data={"name": "bar"})
  +... ])
  +>>> Something.objects.filter(data__at_name="foo").count()
  +1
  +----
  +
  +It also works for array indexes:
  +
  +[source, pycon]
  +----
  +>>> Something.object.bulk_create([
  +...     Something(data=[1,2,3,4]),
  +...     Something(data=[4,5,6,7])
  +... ])
  +>>> Something.objects.filter(data__at_0=4).count()
  +1
  +----
  +
  +In other case, you can execute queries using postgresql operators thaks tu
  +django's queryset `.extra()` method:
  +
   [source, python]
   ----
  -# Lookup by "name" field on json object
  -Something.objects.extra(where=["data->>'name' = %s"], params=["foo"])
  -----
  +>>> Something.objects.extra(where=["data->>'name' = %s"], params=["foo"]).count()
  +1
  +----
  +
  +NOTE: when postgresql 9.4 is released, more lookups will be added.
   
   
   Developers
  
positive.code: - psycopg2 2.5.0+
  - PostgreSQL 9.2+
  
  Limitations
  ~~~~~~~~~~~
  
  - Only supports PostgreSQL >= 9.2
  - Can not be used with other backends, it explictly use psycopg2 extensions system for
    handling with json.
  - Only handles python dicts at this momment (should be improved in future releases).
  - No custom lookups for django 1.7 (should be improved in future releases).
  
  Stable
  
negative.code: django-pgjson documentation
  ===========================
  Andrey Antukh, <niwi@niwi.be>
  0.1.2, 2014-04-17
  
  :toc:
  :numbered:
  