fix: allow passing a filterset class to the filterset factory

django_filters/filterset.py

@@ -458,9 +458,15 @@ class FilterSet(BaseFilterSet, metaclass=FilterSetMetaclass):
     pass
 
 
-def filterset_factory(model, fields=ALL_FIELDS):
-    meta = type(str("Meta"), (object,), {"model": model, "fields": fields})
-    filterset = type(
-        str("%sFilterSet" % model._meta.object_name), (FilterSet,), {"Meta": meta}
+def filterset_factory(model, filterset=FilterSet, fields=None):
+    attrs = {"model": model}
+    if fields is None:
+        if getattr(getattr(filterset, "Meta", {}), "fields", None) is None:
+            attrs["fields"] = ALL_FIELDS
+    else:
+        attrs["fields"] = fields
+    bases = (filterset.Meta,) if hasattr(filterset, "Meta") else ()
+    Meta = type("Meta", bases, attrs)
+    return type(filterset)(
+        str("%sFilterSet" % model._meta.object_name), (filterset,), {"Meta": Meta}
     )
-    return filterset

docs/ref/filterset.txt

@@ -199,3 +199,22 @@ filters for a model field, you can override ``filter_for_lookup()``. Ex::
 
             # use default behavior otherwise
             return super().filter_for_lookup(f, lookup_type)
+
+
+.. _filterset_factory:
+
+Using ``filterset_factory``
+---------------------------
+
+A ``FilterSet`` for a ``model`` can also be created by the
+``filterset_factory``, which creats a ``FilterSet`` with the ``model`` set in
+the FilterSets Meta. You can pass a customized ``FilterSet`` class to the
+``filterset_factory``, which then uses this class a a base for the created
+``FilterSet``. Ex::
+
+    class CustomFilterSet(django_filters.FilterSet):
+        class Meta:
+            form = CustomFilterSetForm
+
+
+    filterset = filterset_factory(Product, filterset=CustomFilterSet)

tests/test_filterset.py

@@ -19,7 +19,7 @@
     NumberFilter,
     UUIDFilter,
 )
-from django_filters.filterset import FILTER_FOR_DBFIELD_DEFAULTS, FilterSet
+from django_filters.filterset import FILTER_FOR_DBFIELD_DEFAULTS, FilterSet, filterset_factory
 from django_filters.widgets import BooleanWidget
 
 from .models import (
@@ -52,10 +52,6 @@ def test_get_declared_filters(self):
     def test_filters_for_model(self):
         pass
 
-    @unittest.skip("todo")
-    def test_filterset_factory(self):
-        pass
-
 
 class DbFieldDefaultFiltersTests(TestCase):
     def test_expected_db_fields_get_filters(self):
@@ -715,6 +711,73 @@ class F(A, B):
             "f5": CharFilter,
         }
 
+    def test_filterset_factory(self):
+        filterset = filterset_factory(Article)
+        self.assertEqual(list(filterset.base_filters), ["name", "published", "author"])
+
+    def test_filterset_factory_fields(self):
+        filterset = filterset_factory(Article, fields=["name"])
+        self.assertEqual(list(filterset.base_filters), ["name"])
+
+    def test_filterset_factory_base_filter(self):
+        class FilterSetBase(FilterSet):
+            f1 = CharFilter()
+            f2 = CharFilter()
+
+        filterset = filterset_factory(Article, filterset=FilterSetBase)
+        self.assertEqual(list(filterset.base_filters), ["name", "published", "author", "f1", "f2"])
+
+    def test_filterset_factory_base_filter_fields(self):
+        class FilterSetBase(FilterSet):
+            f1 = CharFilter()
+            f2 = CharFilter()
+
+        filterset = filterset_factory(Article, filterset=FilterSetBase, fields=["name"])
+        self.assertEqual(list(filterset.base_filters), ["name", "f1", "f2"])
+
+    def test_filterset_factory_base_filter_meta_fields(self):
+        class FilterSetBase(FilterSet):
+            class Meta:
+                fields = ["name"]
+            f1 = CharFilter()
+            f2 = CharFilter()
+
+        filterset = filterset_factory(Article, filterset=FilterSetBase)
+        self.assertEqual(list(filterset.base_filters), ["name", "f1", "f2"])
+
+    def test_filterset_factory_base_filter_fields_and_meta_fields(self):
+        class FilterSetBase(FilterSet):
+            class Meta:
+                fields = ["name"]
+            f1 = CharFilter()
+            f2 = CharFilter()
+
+        filterset = filterset_factory(Article, filterset=FilterSetBase, fields=["author"])
+        self.assertEqual(list(filterset.base_filters), ["author", "f1", "f2"])
+
+    def test_filtesret_factory_base_filter_meta_inheritance_filter_overrides(self):
+        class FilterSetBase(FilterSet):
+            class Meta:
+                filter_overrides = {
+                    models.CharField: {
+                        "filter_class": BooleanFilter,
+                    },
+                }
+
+        filterset = filterset_factory(Article, FilterSetBase)
+
+        f = Article._meta.get_field("author")
+        result, params = filterset.filter_for_lookup(f, "isnull")
+        self.assertEqual(result, BooleanFilter)
+
+    def test_filtesret_factory_base_filter_meta_inheritance_exclude(self):
+        class FilterSetBase(FilterSet):
+            class Meta:
+                exclude = ["published"]
+
+        filterset = filterset_factory(Article, FilterSetBase)
+        self.assertEqual(list(filterset.base_filters), ["name", "author"])
+
 
 class FilterSetInstantiationTests(TestCase):
     class F(FilterSet):