magic-removal: Added first stab at many-to-one descriptor lookup. Now…

… poll_obj.choice_set is created. poll_obj.get_choice_list(), poll_obj.get_choice() and poll_obj.get_choice_count() are still supported temporarily, but that code was marked with a TODO to be deleted.

git-svn-id: http://code.djangoproject.com/svn/django/branches/magic-removal@2141 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/base.py

@@ -202,7 +202,7 @@ def __collect_sub_objects(self, seen_objs):
         seen_objs.setdefault(self.__class__, {})[pk_val] = self
 
         for related in self._meta.get_all_related_objects():
-            rel_opts_name = related.get_accessor_name()
+            rel_opts_name = related.OLD_get_accessor_name()
             if isinstance(related.field.rel, OneToOne):
                 try:
                     sub_obj = getattr(self, 'get_%s' % rel_opts_name)()

django/db/models/fields/related.py

@@ -6,6 +6,7 @@
 from django.core import validators
 from django import forms
 from django.dispatch import dispatcher
+import types
 
 # Values for Relation.edit_inline.
 TABULAR, STACKED = 1, 2
@@ -61,6 +62,38 @@ def do_related_class(self, other, cls):
         related = RelatedObject(other, cls, self)
         self.contribute_to_related_class(other, related)
 
+class RelatedObjectDescriptor(object):
+    # This class provides the functionality that makes the related-object
+    # managers available as attributes on a model class.
+    # In the example "poll.choice_set", the choice_set attribute is a
+    # RelatedObjectDescriptor instance.
+    def __init__(self, related):
+        self.related = related # RelatedObject instance
+        self.manager = None
+
+    def __get__(self, instance, instance_type=None):
+        if instance is None:
+            raise AttributeError, "Manager must be accessed via instance"
+        else:
+            if not self.manager:
+                # Dynamically create a class that subclasses the related
+                # model's default manager.
+                self.manager = types.ClassType('RelatedManager', (self.related.model._default_manager.__class__,), {})()
+
+                # Set core_filters on the new manager to limit it to the
+                # foreign-key relationship.
+                rel_field = self.related.field
+                self.manager.core_filters = {'%s__%s__exact' % (rel_field.name, rel_field.rel.to._meta.pk.name): getattr(instance, rel_field.rel.get_related_field().attname)}
+
+                # Prepare the manager.
+                # TODO: We need to set self.manager.klass because
+                # self.manager._prepare() expects that self.manager.klass is
+                # set. This is slightly hackish.
+                self.manager.klass = self.related.model
+                self.manager._prepare()
+
+            return self.manager
+
 class ForeignKey(RelatedField, Field):
     empty_strings_allowed = False
     def __init__(self, to, to_field=None, **kwargs):
@@ -151,7 +184,13 @@ def contribute_to_class(self, cls, name):
         setattr(cls, 'get_%s' % self.name, curry(cls._get_foreign_key_object, field_with_rel=self))
 
     def contribute_to_related_class(self, cls, related):
-        rel_obj_name = related.get_accessor_name()
+        setattr(cls, related.get_accessor_name(), RelatedObjectDescriptor(related))
+
+        # TODO: Delete the rest of this function and RelatedObject.OLD_get_accessor_name()
+        # to remove support for old-style related lookup.
+
+        rel_obj_name = related.OLD_get_accessor_name
+
         # Add "get_thingie" methods for many-to-one related objects.
         # EXAMPLE: Poll.get_choice()
         setattr(cls, 'get_%s' % rel_obj_name, curry(cls._get_related, method_name='get_object', rel_class=related.model, rel_field=related.field))
@@ -206,7 +245,7 @@ def contribute_to_class(self, cls, name):
         setattr(cls, 'get_%s' % self.name, curry(cls._get_foreign_key_object, field_with_rel=self))
 
     def contribute_to_related_class(self, cls, related):
-        rel_obj_name = related.get_accessor_name()
+        rel_obj_name = related.OLD_get_accessor_name()
         # Add "get_thingie" methods for one-to-one related objects.
         # EXAMPLE: Place.get_restaurants_restaurant()
         setattr(cls, 'get_%s' % rel_obj_name,
@@ -296,7 +335,7 @@ def contribute_to_class(self, cls, name):
         setattr(cls, 'set_%s' % self.name, curry(cls._set_many_to_many_objects, field_with_rel=self))
 
     def contribute_to_related_class(self, cls, related):
-        rel_obj_name = related.get_accessor_name()
+        rel_obj_name = related.OLD_get_accessor_name()
         setattr(cls, 'get_%s' % rel_obj_name, curry(cls._get_related_many_to_many, method_name='get_object', rel_class=related.model, rel_field=related.field))
         setattr(cls, 'get_%s_count' % rel_obj_name, curry(cls._get_related_many_to_many, method_name='get_count', rel_class=related.model, rel_field=related.field))
         setattr(cls, 'get_%s_list' % rel_obj_name, curry(cls._get_related_many_to_many, method_name='get_list', rel_class=related.model, rel_field=related.field))

django/db/models/manipulators.py

@@ -154,7 +154,7 @@ def save(self, new_data):
                     if self.change:
                         if rel_new_data[related.opts.pk.name][0]:
                             try:
-                                old_rel_obj = getattr(self.original_object, 'get_%s' % related.get_accessor_name() )(**{'%s__exact' % related.opts.pk.name: rel_new_data[related.opts.pk.attname][0]})
+                                old_rel_obj = getattr(self.original_object, 'get_%s' % related.OLD_get_accessor_name() )(**{'%s__exact' % related.opts.pk.name: rel_new_data[related.opts.pk.attname][0]})
                             except ObjectDoesNotExist:
                                 pass
 

django/db/models/related.py

@@ -44,7 +44,7 @@ def extract_data(self, data):
     def get_list(self, parent_instance=None):
         "Get the list of this type of object from an instance of the parent class."
         if parent_instance != None:
-            func_name = 'get_%s_list' % self.get_accessor_name()
+            func_name = 'get_%s_list' % self.OLD_get_accessor_name()
             func = getattr(parent_instance, func_name)
             return func()
         else:
@@ -80,19 +80,12 @@ def bind(self, field_mapping, original, bound_related_object_class=BoundRelatedO
     def get_accessor_name(self):
         # This method encapsulates the logic that decides what name to give an
         # accessor descriptor that retrieves related many-to-one or
-        # many-to-many objects. Usually it just uses the lower-cased
-        # object_name, but if the related object is in another app, the related
-        # object's app_label is appended.
-        #
-        # Examples:
-        #
-        #   # Normal case -- a related object in the same app.
-        #   # This method returns "choice".
-        #   Poll.choice_set
-        #
-        #   # A related object in a different app.
-        #   # This method returns "lcom_bestofaward".
-        #   Place.lcom_bestofaward_set # "lcom_bestofaward"
+        # many-to-many objects. It uses the lower-cased object_name + "_set",
+        # but this can be overridden with the "related_name" option.
+        return self.field.rel.related_name or (self.opts.object_name.lower() + '_set')
+
+    # TODO: Remove this.
+    def OLD_get_accessor_name(self):
         rel_obj_name = self.field.rel.related_name or self.opts.object_name.lower()
         if self.parent_model._meta.app_label != self.opts.app_label:
             rel_obj_name = '%s_%s' % (self.opts.app_label, rel_obj_name)