Fixed carltongibson#20. When you filter on a multiple choice field for all options itself the same as doing it for no options, which is way more efficient at the DB level.

Author: alex

django_filters/filters.py

@@ -83,8 +83,13 @@ class MultipleChoiceFilter(Filter):
     field_class = forms.MultipleChoiceField
 
     def filter(self, qs, value):
+        value = value or ()
+        # TODO: this is a bit of a hack, but ModelChoiceIterator doesn't have a
+        # __len__ method
+        if len(value) == len(list(self.field.choices)):
+            return qs
         q = Q()
-        for v in (value or ()):
+        for v in value:
             q |= Q(**{self.name: v})
         return qs.filter(q).distinct()
 

django_filters/tests/__init__.py

@@ -1,6 +1,6 @@
 from tests import (GenericViewTests, InheritanceTest, ModelInheritanceTest,
     DateRangeFilterTest, FilterSetForm, AllValuesFilterTest, InitialValueTest,
-    RelatedObjectTest, filter_tests)
+    RelatedObjectTest, MultipleChoiceFilterTest, filter_tests)
 
 __test__ = {
     'filter_tests': filter_tests,

django_filters/tests/tests.py

@@ -133,6 +133,18 @@ class Meta:
         self.assertEqual(str(F().form), form_html)
 
 
+class MultipleChoiceFilterTest(TestCase):
+    fixtures = ['test_data']
+
+    def test_all_choices_selected(self):
+        class F(django_filters.FilterSet):
+            class Meta:
+                model = User
+                fields = ["status"]
+        
+        self.assertEqual(list(F({"status": [0, 1]}).qs), list(User.objects.all()))
+
+
 filter_tests = """
 >>> from datetime import datetime
 >>> from django import forms