POC to address concerns about manager-only methods. Refs https://code…

….djangoproject.com/ticket/20625#comment:22

django/db/models/manager.py

@@ -58,7 +58,7 @@ class RenameManagerMethods(RenameMethodsBase):
 class _Manager(six.with_metaclass(RenameManagerMethods)):
     # Tracks each time a Manager instance is created. Used to retain order.
     creation_counter = 0
-    queryset_class = QuerySet
+    _queryset_class = QuerySet
 
     def __init__(self):
         super(_Manager, self).__init__()
@@ -121,7 +121,7 @@ def get_queryset(self):
         """Returns a new QuerySet object.  Subclasses can override this method
         to easily customize the behavior of the Manager.
         """
-        return self.queryset_class(self.model, using=self._db)
+        return self._queryset_class(self.model, using=self._db)
 
     def all(self):
         # All can't be proxied to QuerySet, as prefetch_related is lost on
@@ -134,7 +134,7 @@ def _insert(self, objs, fields, **kwargs):
     def raw(self, raw_query, params=None, *args, **kwargs):
         return RawQuerySet(raw_query=raw_query, model=self.model, params=params, using=self._db, *args, **kwargs)
 
-Manager = QuerySet.manager_cls(base_cls=_Manager)
+Manager = QuerySet.get_manager_class(base_cls=_Manager)
 
 
 class ManagerDescriptor(object):

django/db/models/query.py

@@ -30,6 +30,9 @@ class QuerySet(object):
     """
     Represents a lazy database lookup for a set of objects.
     """
+
+    base_manager_class = None
+
     def __init__(self, model=None, query=None, using=None):
         self.model = model
         self._db = using
@@ -42,7 +45,7 @@ def __init__(self, model=None, query=None, using=None):
         self._known_related_objects = {}        # {rel_field, {pk: rel_obj}}
 
     @classmethod
-    def manager_cls(cls, base_cls=None):
+    def get_manager_class(cls, base_cls=None):
         """
         Creates a manager class for this QuerySet class.
         """
@@ -56,18 +59,20 @@ def manager_copy(self, *args, **kwargs):
                 do_copy = getattr(maybe_copy, 'manager', None)
                 if do_copy or do_copy is None and not name.startswith('_'):
                     new_methods[name] = create_method(name)
+        if base_cls is None:
+            base_cls = cls.base_manager_class
         if base_cls is None:
             from django.db.models.manager import Manager as base_cls
         manager_cls = type(
             cls.__name__ + 'Manager',
             (base_cls,),
             new_methods)
-        manager_cls.queryset_class = cls
+        manager_cls._queryset_class = cls
         return manager_cls
 
     @classmethod
     def as_manager(cls, base_cls=None):
-        manager_cls = cls.manager_cls(base_cls=base_cls)
+        manager_cls = cls.get_manager_class(base_cls)
         return manager_cls()
 
     ########################

tests/custom_managers/models.py

@@ -35,13 +35,24 @@ def bar(self, *args, **kwargs):
         return self.all()
     bar.manager = True
 
+class MyManager(models.Manager):
+    def manager_only(self):
+        pass
+
+class MyQuerySet(models.QuerySet):
+    base_manager_class = MyManager
+
+    def manager_and_queryset_method(self):
+        pass
+
 @python_2_unicode_compatible
 class Person(models.Model):
     first_name = models.CharField(max_length=30)
     last_name = models.CharField(max_length=30)
     fun = models.BooleanField()
     objects = PersonManager()
     other_objects = CustomQuerySet.as_manager(base_cls=PersonManager)
+    other_other_objects = MyQuerySet.as_manager()
 
     def __str__(self):
         return "%s %s" % (self.first_name, self.last_name)

tests/custom_managers/tests.py

@@ -25,6 +25,14 @@ def test_manager(self):
         )
         print Person.other_objects.filter(fun=False)
         print Person.other_objects.bar()
+
+        Person.other_other_objects.manager_and_queryset_method()
+        Person.other_other_objects.all().manager_and_queryset_method()
+
+        Person.other_other_objects.manager_only()
+        with self.assertRaises(AttributeError):
+            Person.other_other_objects.all().manager_only()
+
         # The RelatedManager used on the 'books' descriptor extends the default
         # manager
         self.assertIsInstance(p2.books, PublishedBookManager)