Use plain model.Manager, or suitable proxy, for model saving.

We can't use the default manager in Model.save_base(), since we need to
retrieve existing objects which might be filtered out by that manager. We now
always use a plain Manager instance at that point (or something that can
replace it, such as a GeoManager), making all existing rows in the
database visible to the saving code.

The logic for detecting a "suitable replacement" plain base is the same as for
related fields: if the use_for_related_fields is set on the manager subclass,
we can use it. The general requirement here is that we want a base class that
returns the appropriate QuerySet subclass, but does not restrict the rows
returned.

Fixed #8990, #9527.

Refs #2698 (which is not fixed by this change, but it's the first part of a
larger change to fix that bug.)

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10056 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/base.py

@@ -69,6 +69,7 @@ class ModelBase(type):
 
         if getattr(new_class, '_default_manager', None):
             new_class._default_manager = None
+            new_class._base_manager = None
 
         # Bail out early if we have already created this class.
         m = get_model(new_class._meta.app_label, name, False)
@@ -369,7 +370,7 @@ class Model(object):
         pk_val = self._get_pk_val(meta)
         pk_set = pk_val is not None
         record_exists = True
-        manager = cls._default_manager
+        manager = cls._base_manager
         if pk_set:
             # Determine whether a record with the primary key already exists.
             if (force_update or (not force_insert and

django/db/models/manager.py

@@ -5,8 +5,16 @@ from django.db.models import signals
 from django.db.models.fields import FieldDoesNotExist
 
 def ensure_default_manager(sender, **kwargs):
+    """
+    Ensures that a Model subclass contains a default manager  and sets the
+    _default_manager attribute on the class. Also sets up the _base_manager
+    points to a plain Manager instance (which could be the same as
+    _default_manager if it's not a subclass of Manager).
+    """
     cls = sender
-    if not getattr(cls, '_default_manager', None) and not cls._meta.abstract:
+    if cls._meta.abstract:
+        return
+    if not getattr(cls, '_default_manager', None):
         # Create the default manager, if needed.
         try:
             cls._meta.get_field('objects')
@@ -14,6 +22,22 @@ def ensure_default_manager(sender, **kwargs):
         except FieldDoesNotExist:
             pass
         cls.add_to_class('objects', Manager())
+        cls._base_manager = cls.objects
+    elif not getattr(cls, '_base_manager', None):
+        default_mgr = cls._default_manager.__class__
+        if (default_mgr is Manager or
+                getattr(default_mgr, "use_for_related_fields", False)):
+            cls._base_manager = cls._default_manager
+        else:
+            # Default manager isn't a plain Manager class, or a suitable
+            # replacement, so we walk up the base class hierarchy until we hit
+            # something appropriate.
+            for base_class in default_mgr.mro()[1:]:
+                if (base_class is Manager or
+                        getattr(base_class, "use_for_related_fields", False)):
+                    cls.add_to_class('_base_manager', base_class())
+                    return
+            raise AssertionError("Should never get here. Please report a bug, including your model and model manager setup.")
 
 signals.class_prepared.connect(ensure_default_manager)
 

tests/regressiontests/custom_managers_regress/models.py

@@ -0,0 +1,38 @@
+"""
+Regression tests for custom manager classes.
+"""
+
+from django.db import models
+
+class RestrictedManager(models.Manager):
+    """
+    A manager that filters out non-public instances.
+    """
+    def get_query_set(self):
+        return super(RestrictedManager, self).get_query_set().filter(is_public=True)
+
+class RestrictedClass(models.Model):
+    name = models.CharField(max_length=50)
+    is_public = models.BooleanField(default=False)
+
+    objects = RestrictedManager()
+    plain_manager = models.Manager()
+
+    def __unicode__(self):
+        return self.name
+
+__test__ = {"tests": """
+Even though the default manager filters out some records, we must still be able
+to save (particularly, save by updating existing records) those filtered
+instances. This is a regression test for #FIXME.
+>>> obj = RestrictedClass.objects.create(name="hidden")
+>>> obj.name = "still hidden"
+>>> obj.save()
+
+# If the hidden object wasn't seen during the save process, there would now be
+# two objects in the database.
+>>> RestrictedClass.plain_manager.count()
+1
+
+"""
+}