Formalize filter binding to parent

django_filters/filters.py

@@ -83,6 +83,16 @@ def __init__(self, field_name=None, lookup_expr=None, *, label=None,
         self.creation_counter = Filter.creation_counter
         Filter.creation_counter += 1
 
+    def bind(self, attr, parent):
+        """Bind the filter to its parent filterset.
+
+        Provides both the filter's attribute name on the filterset and the
+        parent filterset instance. Called when the parent is initialized.
+        """
+        self.attr = attr
+        self.parent = parent
+        self.model = parent.queryset.model
+
     def get_method(self, qs):
         """Return filter method based on whether we're excluding
            or simply filtering.

django_filters/filterset.py

@@ -190,7 +190,6 @@ class BaseFilterSet(object):
     def __init__(self, data=None, queryset=None, *, request=None, prefix=None):
         if queryset is None:
             queryset = self._meta.model._default_manager.all()
-        model = queryset.model
 
         self.is_bound = data is not None
         self.data = data or {}
@@ -200,10 +199,8 @@ def __init__(self, data=None, queryset=None, *, request=None, prefix=None):
 
         self.filters = copy.deepcopy(self.base_filters)
 
-        # propagate the model and filterset to the filters
-        for filter_ in self.filters.values():
-            filter_.model = model
-            filter_.parent = self
+        for filter_name, f in self.filters.items():
+            f.bind(filter_name, self)
 
     def is_valid(self):
         """

tests/test_filters.py

@@ -94,6 +94,15 @@ def test_field_with_single_lookup_expr(self):
         field = f.field
         self.assertIsInstance(field, forms.Field)
 
+    def test_filterset_bind(self):
+        m = mock.Mock(queryset=User.objects.all())
+        f = Filter()
+        f.bind('name', m)
+
+        self.assertEqual(f.attr, 'name')
+        self.assertIs(f.parent, m)
+        self.assertIs(f.model, User)
+
     def test_field_params(self):
         with mock.patch.object(Filter, 'field_class',
                                spec=['__call__']) as mocked:
@@ -161,6 +170,7 @@ def test_filter_using_method(self):
         qs = mock.NonCallableMock(spec=[])
         method = mock.Mock()
         f = Filter(method=method)
+        f.bind('name', mock.Mock())
         result = f.filter(qs, 'value')
         method.assert_called_once_with(qs, None, 'value')
         self.assertNotEqual(qs, result)
@@ -721,7 +731,7 @@ def test_callable_queryset(self):
         qs_callable = mock.Mock(return_value=qs)
 
         f = ModelChoiceFilter(queryset=qs_callable)
-        f.parent = mock.Mock(request=request)
+        f.bind('name', mock.Mock(request=request))
         field = f.field
 
         qs_callable.assert_called_with(request)
@@ -735,7 +745,7 @@ class F(ModelChoiceFilter):
             get_queryset = mock.create_autospec(ModelChoiceFilter.get_queryset, return_value=qs)
 
         f = F()
-        f.parent = mock.Mock(request=request)
+        f.bind('name', mock.Mock(request=request))
         field = f.field
 
         f.get_queryset.assert_called_with(f, request)
@@ -787,7 +797,7 @@ def test_callable_queryset(self):
         qs_callable = mock.Mock(return_value=qs)
 
         f = ModelMultipleChoiceFilter(queryset=qs_callable)
-        f.parent = mock.Mock(request=request)
+        f.bind('name', mock.Mock(request=request))
         field = f.field
 
         qs_callable.assert_called_with(request)
@@ -1261,19 +1271,14 @@ def test_default_field_without_assigning_model(self):
             f.field
 
     def test_default_field_with_assigning_model(self):
-        mocked = mock.Mock()
-        chained_call = '.'.join(['_default_manager', 'distinct.return_value',
-                                 'order_by.return_value',
-                                 'values_list.return_value'])
-        mocked.configure_mock(**{chained_call: iter([])})
-        f = AllValuesFilter()
-        f.model = mocked
-        field = f.field
-        self.assertIsInstance(field, forms.ChoiceField)
+        f = AllValuesFilter(field_name='username')
+        f.bind('name', mock.Mock(queryset=User.objects.all()))
+
+        self.assertIsInstance(f.field, forms.ChoiceField)
 
     def test_empty_value_in_choices(self):
         f = AllValuesFilter(field_name='username')
-        f.model = User
+        f.bind('name', mock.Mock(queryset=User.objects.all()))
 
         self.assertEqual(list(f.field.choices), [
             ('', '---------'),
@@ -1295,7 +1300,7 @@ def test_normalize_lookup_with_display_label(self):
     def test_lookup_choices_default(self):
         # Lookup choices should default to the model field's registered lookups
         f = LookupChoiceFilter(field_name='username', lookup_choices=None)
-        f.model = User
+        f.bind('name', mock.Mock(queryset=User.objects.all()))
 
         choice_field = f.field.fields[1]
         self.assertEqual(