Make default FILTER_BACKEND = None

docs/api-guide/filtering.md

@@ -82,24 +82,30 @@ We can override `.get_queryset()` to deal with URLs such as `http://example.com/
 
 As well as being able to override the default queryset, REST framework also includes support for generic filtering backends that allow you to easily construct complex filters that can be specified by the client using query parameters.
 
-REST framework supports pluggable backends to implement filtering, and includes a default implementation which uses the [django-filter] package.
+REST framework supports pluggable backends to implement filtering, and provides an implementation which uses the [django-filter] package.
 
 To use REST framework's default filtering backend, first install `django-filter`.
 
     pip install -e git+https://github.com/alex/django-filter.git#egg=django-filter
 
+You must also set the filter backend to `DjangoFilterBackend` in your settings:
+
+    REST_FRAMEWORK = {
+        'FILTER_BACKEND': 'rest_framework.filters.DjangoFilterBackend'
+    }
+
 **Note**: The currently supported version of `django-filter` is the `master` branch.  A PyPI release is expected to be coming soon.
 
-## Specifying filter fields
-
-**TODO**: Document setting `.filter_fields` on the view.
-
 ## Specifying a FilterSet
 
 **TODO**: Document setting `.filter_class` on the view.
 
 **TODO**: Note support for `lookup_type`, double underscore relationship spanning, and ordering.
 
+## Specifying filter fields
+
+**TODO**: Document setting `.filter_fields` on the view.
+
 **TODO**: Note that overiding `get_queryset()` can be used together with generic filtering 
 
 ---

rest_framework/filters.py

@@ -17,6 +17,10 @@ class DjangoFilterBackend(BaseFilterBackend):
     """
     A filter backend that uses django-filter.
     """
+    default_filter_set = django_filters.FilterSet
+
+    def __init__(self):
+        assert django_filters, 'Using DjangoFilterBackend, but django-filter is not installed'
 
     def get_filter_class(self, view):
         """
@@ -24,20 +28,21 @@ class DjangoFilterBackend(BaseFilterBackend):
         """
         filter_class = getattr(view, 'filter_class', None)
         filter_fields = getattr(view, 'filter_fields', None)
-        filter_model = getattr(view, 'model', None)
+        view_model = getattr(view, 'model', None)
-
-        if filter_class or filter_fields:
-            assert django_filters, 'django-filter is not installed'
 
         if filter_class:
-            assert issubclass(filter_class.Meta.model, filter_model), \
+            filter_model = filter_class.Meta.model
-                '%s is not a subclass of %s' % (filter_class.Meta.model, filter_model)
+
+            assert issubclass(filter_model, view_model), \
+                'FilterSet model %s does not match view model %s' % \
+                (filter_model, view_model)
+
             return filter_class
 
         if filter_fields:
-            class AutoFilterSet(django_filters.FilterSet):
+            class AutoFilterSet(self.default_filter_set):
                 class Meta:
-                    model = filter_model
+                    model = view_model
                 fields = filter_fields
             return AutoFilterSet
 

rest_framework/runtests/settings.py

@@ -107,6 +107,7 @@ import django
 if django.VERSION < (1, 3):
     INSTALLED_APPS += ('staticfiles',)
 
+
 # If we're running on the Jenkins server we want to archive the coverage reports as XML.
 import os
 if os.environ.get('HUDSON_URL', None):

rest_framework/settings.py

@@ -55,7 +55,7 @@ DEFAULTS = {
         'anon': None,
     },
     'PAGINATE_BY': None,
-    'FILTER_BACKEND': 'rest_framework.filters.DjangoFilterBackend',
+    'FILTER_BACKEND': None,
 
     'UNAUTHENTICATED_USER': 'django.contrib.auth.models.AnonymousUser',
     'UNAUTHENTICATED_TOKEN': None,
@@ -144,8 +144,15 @@ class APISettings(object):
         if val and attr in self.import_strings:
             val = perform_import(val, attr)
 
+        self.validate_setting(attr, val)
+
         # Cache the result
         setattr(self, attr, val)
         return val
 
+    def validate_setting(self, attr, val):
+        if attr == 'FILTER_BACKEND' and val is not None:
+            # Make sure we can initilize the class
+            val()
+
 api_settings = APISettings(USER_SETTINGS, DEFAULTS, IMPORT_STRINGS)

rest_framework/tests/filterset.py

@@ -3,7 +3,7 @@ from decimal import Decimal
 from django.test import TestCase
 from django.test.client import RequestFactory
 from django.utils import unittest
-from rest_framework import generics, status
+from rest_framework import generics, status, filters
 from rest_framework.compat import django_filters
 from rest_framework.tests.models import FilterableItem, BasicModel
 
@@ -15,6 +15,7 @@ if django_filters:
     class FilterFieldsRootView(generics.ListCreateAPIView):
         model = FilterableItem
         filter_fields = ['decimal', 'date']
+        filter_backend = filters.DjangoFilterBackend
 
     # These class are used to test a filter class.
     class SeveralFieldsFilter(django_filters.FilterSet):
@@ -29,6 +30,7 @@ if django_filters:
     class FilterClassRootView(generics.ListCreateAPIView):
         model = FilterableItem
         filter_class = SeveralFieldsFilter
+        filter_backend = filters.DjangoFilterBackend
 
     # These classes are used to test a misconfigured filter class.
     class MisconfiguredFilter(django_filters.FilterSet):
@@ -41,6 +43,7 @@ if django_filters:
     class IncorrectlyConfiguredRootView(generics.ListCreateAPIView):
         model = FilterableItem
         filter_class = MisconfiguredFilter
+        filter_backend = filters.DjangoFilterBackend
 
 
 class IntegrationTestFiltering(TestCase):

rest_framework/tests/pagination.py

@@ -4,7 +4,7 @@ from django.core.paginator import Paginator
 from django.test import TestCase
 from django.test.client import RequestFactory
 from django.utils import unittest
-from rest_framework import generics, status, pagination
+from rest_framework import generics, status, pagination, filters
 from rest_framework.compat import django_filters
 from rest_framework.tests.models import BasicModel, FilterableItem
 
@@ -31,6 +31,7 @@ if django_filters:
         model = FilterableItem
         paginate_by = 10
         filter_class = DecimalFilter
+        filter_backend = filters.DjangoFilterBackend
 
 
 class IntegrationTestPagination(TestCase):