To do `GROUP_BY` queries in django requires one to use `.values()`
eg this groups posts by user getting a count of posts per user.
```
Posts.objects.order_by('user').values('user').annotate(post_count=Count('post'))
```
This would produce a value queryset which serializes its result
objects as dictionaries while `CursorPagination` requires a queryset
with result objects that are model instances.
This commit enables cursor pagination for value querysets.
- had to mangle the tests a bit to test it out. They might need
some refactoring.
- tried the same for `.values_list()` but it turned out to be
trickier than I expected since you have to use tuple indexes.
* Start test case
* Added 'requests' test client
* Address typos
* Graceful fallback if requests is not installed.
* Add cookie support
* Tests for auth and CSRF
* Py3 compat
* py3 compat
* py3 compat
* Add get_requests_client
* Added SchemaGenerator.should_include_link
* add settings for html cutoff on related fields
* Router doesn't work if prefix is blank, though project urls.py handles prefix
* Fix Django 1.10 to-many deprecation
* Add django.core.urlresolvers compatibility
* Update django-filter & django-guardian
* Check for empty router prefix; adjust URL accordingly
It's easiest to fix this issue after we have made the regex. To try
to fix it before would require doing something different for List vs
Detail, which means we'd have to know which type of url we're
constructing before acting accordingly.
* Fix misc django deprecations
* Use TOC extension instead of header
* Fix deprecations for py3k
* Add py3k compatibility to is_simple_callable
* Add is_simple_callable tests
* Drop python 3.2 support (EOL, Dropped by Django)
* schema_renderers= should *set* the renderers, not append to them.
* API client (#4424)
* Fix release notes
* Add note about 'User account is disabled.' vs 'Unable to log in'
* Clean up schema generation (#4527)
* Handle multiple methods on custom action (#4529)
* RequestsClient, CoreAPIClient
* exclude_from_schema
* Added 'get_schema_view()' shortcut
* Added schema descriptions
* Better descriptions for schemas
* Add type annotation to schema generation
* Coerce schema 'pk' in path to actual field name
* Deprecations move into assertion errors
* Use get_schema_view in tests
* Updte CoreJSON media type
* Handle schema structure correctly when path prefixs exist. Closes#4401
* Add PendingDeprecation to Router schema generation.
* Added SCHEMA_COERCE_PATH_PK and SCHEMA_COERCE_METHOD_NAMES
* Renamed and documented 'get_schema_fields' interface.
