queryset-refactor: Added the ability to manually specify a child-parent link.

git-svn-id: http://code.djangoproject.com/svn/django/branches/queryset-refactor@7142 bcc190cf-cafb-0310-a4f2-bffc1f526a37

5 files changed, 85 insertions, 38 deletions

diff --git a/django/db/models/base.py b/django/db/models/base.py
index 9a4d6664ab..dc2b4ca0fe 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -59,21 +59,6 @@ class ModelBase(type):
                 if not hasattr(meta, 'get_latest_by'):
                     new_class._meta.get_latest_by = base_meta.get_latest_by
 
-        # Do the appropriate setup for any model parents.
-        abstract_parents = []
-        for base in parents:
-            if not hasattr(base, '_meta'):
-                # Things without _meta aren't functional models, so they're
-                # uninteresting parents.
-                continue
-            if not base._meta.abstract:
-                attr_name = '%s_ptr' % base._meta.module_name
-                field = OneToOneField(base, name=attr_name, auto_created=True)
-                new_class.add_to_class(attr_name, field)
-                new_class._meta.parents[base] = field
-            else:
-                abstract_parents.append(base)
-
         if getattr(new_class, '_default_manager', None) is not None:
             # We have a parent who set the default manager. We need to override
             # this.
@@ -93,13 +78,32 @@ class ModelBase(type):
         for obj_name, obj in attrs.items():
             new_class.add_to_class(obj_name, obj)
 
-        for parent in abstract_parents:
-            names = [f.name for f in new_class._meta.local_fields + new_class._meta.many_to_many]
-            for field in parent._meta.local_fields:
-                if field.name in names:
-                    raise TypeError('Local field %r in class %r clashes with field of similar name from abstract base class %r'
-                            % (field.name, name, parent.__name__))
-                new_class.add_to_class(field.name, field)
+        # Do the appropriate setup for any model parents.
+        o2o_map = dict([(f.rel.to, f) for f in new_class._meta.local_fields
+                if isinstance(f, OneToOneField)])
+        for base in parents:
+            if not hasattr(base, '_meta'):
+                # Things without _meta aren't functional models, so they're
+                # uninteresting parents.
+                continue
+            if not base._meta.abstract:
+                if base in o2o_map:
+                    field = o2o_map[base]
+                    field.primary_key = True
+                    new_class._meta.setup_pk(field)
+                else:
+                    attr_name = '%s_ptr' % base._meta.module_name
+                    field = OneToOneField(base, name=attr_name,
+                            auto_created=True, parent_link=True)
+                    new_class.add_to_class(attr_name, field)
+                new_class._meta.parents[base] = field
+            else:
+                names = [f.name for f in new_class._meta.local_fields + new_class._meta.many_to_many]
+                for field in base._meta.local_fields:
+                    if field.name in names:
+                        raise TypeError('Local field %r in class %r clashes with field of similar name from abstract base class %r'
+                                % (field.name, name, base.__name__))
+                    new_class.add_to_class(field.name, field)
 
         if abstract:
             # Abstract base models can't be instantiated and don't appear in
diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index 39fe6d794c..4ebf48beab 100644
--- a/django/db/models/fields/related.py
+++ b/django/db/models/fields/related.py
@@ -461,8 +461,9 @@ class ReverseManyRelatedObjectsDescriptor(object):
 
 class ManyToOneRel(object):
     def __init__(self, to, field_name, num_in_admin=3, min_num_in_admin=None,
-        max_num_in_admin=None, num_extra_on_change=1, edit_inline=False,
-        related_name=None, limit_choices_to=None, lookup_overrides=None, raw_id_admin=False):
+            max_num_in_admin=None, num_extra_on_change=1, edit_inline=False,
+            related_name=None, limit_choices_to=None, lookup_overrides=None,
+            raw_id_admin=False, parent_link=False):
         try:
             to._meta
         except AttributeError: # to._meta doesn't exist, so it must be RECURSIVE_RELATIONSHIP_CONSTANT
@@ -477,6 +478,7 @@ class ManyToOneRel(object):
         self.lookup_overrides = lookup_overrides or {}
         self.raw_id_admin = raw_id_admin
         self.multiple = True
+        self.parent_link = parent_link
 
     def get_related_field(self):
         """
@@ -489,14 +491,15 @@ class OneToOneRel(ManyToOneRel):
     def __init__(self, to, field_name, num_in_admin=0, min_num_in_admin=None,
             max_num_in_admin=None, num_extra_on_change=None, edit_inline=False,
             related_name=None, limit_choices_to=None, lookup_overrides=None,
-            raw_id_admin=False):
+            raw_id_admin=False, parent_link=False):
         # NOTE: *_num_in_admin and num_extra_on_change are intentionally
         # ignored here. We accept them as parameters only to match the calling
         # signature of ManyToOneRel.__init__().
         super(OneToOneRel, self).__init__(to, field_name, num_in_admin,
                 edit_inline=edit_inline, related_name=related_name,
                 limit_choices_to=limit_choices_to,
-                lookup_overrides=lookup_overrides, raw_id_admin=raw_id_admin)
+                lookup_overrides=lookup_overrides, raw_id_admin=raw_id_admin,
+                parent_link=parent_link)
         self.multiple = False
 
 class ManyToManyRel(object):
@@ -541,7 +544,8 @@ class ForeignKey(RelatedField, Field):
             related_name=kwargs.pop('related_name', None),
             limit_choices_to=kwargs.pop('limit_choices_to', None),
             lookup_overrides=kwargs.pop('lookup_overrides', None),
-            raw_id_admin=kwargs.pop('raw_id_admin', False))
+            raw_id_admin=kwargs.pop('raw_id_admin', False),
+            parent_link=kwargs.pop('parent_link', False))
         Field.__init__(self, **kwargs)
 
         self.db_index = True
diff --git a/django/db/models/options.py b/django/db/models/options.py
index a5e853de33..7fa7fe0174 100644
--- a/django/db/models/options.py
+++ b/django/db/models/options.py
@@ -113,22 +113,22 @@ class Options(object):
         # self.many_to_many.
         if field.rel and isinstance(field.rel, ManyToManyRel):
             self.local_many_to_many.insert(bisect(self.local_many_to_many, field), field)
+            if hasattr(self, '_m2m_cache'):
+                del self._m2m_cache
         else:
             self.local_fields.insert(bisect(self.local_fields, field), field)
-            if not self.pk and field.primary_key:
-                self.pk = field
-                field.serialize = False
+            self.setup_pk(field)
+            if hasattr(self, '_field_cache'):
+                del self._field_cache
 
-        # All of these internal caches need to be updated the next time they
-        # are used.
-        # TODO: Do this more neatly. (Also, use less caches!)
-        if hasattr(self, '_field_cache'):
-            del self._field_cache
-        if hasattr(self, '_m2m_cache'):
-            del self._m2m_cache
         if hasattr(self, '_name_map'):
             del self._name_map
 
+    def setup_pk(self, field):
+        if not self.pk and field.primary_key:
+            self.pk = field
+            field.serialize = False
+
     def __repr__(self):
         return '<Options for %s>' % self.object_name
 
@@ -315,7 +315,7 @@ class Options(object):
         parent_list = self.get_parent_list()
         for parent in self.parents:
             for obj, model in parent._meta.get_all_related_objects_with_model():
-                if obj.field.creation_counter < 0 and obj.model not in parent_list:
+                if (obj.field.creation_counter < 0 or obj.field.rel.parent_link) and obj.model not in parent_list:
                     continue
                 if not model:
                     cache[obj] = parent
diff --git a/docs/model-api.txt b/docs/model-api.txt
index 2687c00d14..1926495728 100644
--- a/docs/model-api.txt
+++ b/docs/model-api.txt
@@ -1000,6 +1000,21 @@ As with ``ForeignKey``, a relationship to self can be defined by using the
 string ``"self"`` instead of the model name; references to as-yet undefined
 models can be made by using a string containing the model name.
 
+Finally, ``OneToOneField`` takes the following extra option:
+
+    =======================  ============================================================
+    Argument                 Description
+    =======================  ============================================================
+    ``parent_link``          When ``True`` and used in a model inherited from
+                             another model, indicates that this field should
+                             be used as the link from the child back to the
+                             parent. See `Model inheritance`_ for more
+                             details.
+
+                             **New in Django development version**
+
+    =======================  ============================================================
+
 **New in Django development version:** ``OneToOneField`` classes used to
 automatically become the primary key on a model. This is no longer true,
 although you can manually pass in the ``primary_key`` attribute if you like.
@@ -1036,6 +1051,14 @@ Model metadata is "anything that's not a field", such as ordering options, etc.
 Here's a list of all possible ``Meta`` options. No options are required. Adding
 ``class Meta`` to a model is completely optional.
 
+``abstract``
+------------
+
+**New in Django development version**
+
+When set to ``True``, denotes this model as an abstract base class. See
+`Abstract base classes`_ for more details. Defaults to ``False``.
+
 ``db_table``
 ------------
 
@@ -2192,6 +2215,20 @@ For more information about reverse relations, refer to the `Database API
 reference`_ . For now, just remember to run ``manage.py validate`` when
 you're writing your models and pay attention to the error messages.
 
+Specifying the parent link field
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+As mentioned, Django will automatically create a ``OneToOneField`` linking
+your child class back any non-abstract parent models. If you want to control
+the name of the attribute linking back to the parent, you can create your own
+link field and pass it ``parent_link=True``. For example, to explicitly
+specify the field that will link ``Supplier`` to ``Place`` in the above
+example, you could write::
+
+    class Supplier(Place):
+        parent = models.OneToOneField(Place, parent_link=True)
+        ...
+
 Multiple inheritance
 --------------------
 
diff --git a/tests/modeltests/model_inheritance/models.py b/tests/modeltests/model_inheritance/models.py
index 1187c5fe64..df0fb77ccb 100644
--- a/tests/modeltests/model_inheritance/models.py
+++ b/tests/modeltests/model_inheritance/models.py
@@ -67,6 +67,8 @@ class Supplier(Place):
         return u"%s the supplier" % self.name
 
 class ParkingLot(Place):
+    # An explicit link to the parent (we can control the attribute name).
+    parent = models.OneToOneField(Place, primary_key=True, parent_link=True)
     main_site = models.ForeignKey(Place, related_name='lot')
 
     def __unicode__(self):