Added optional rel_name parameter to ManyToManyField, which makes it …

…possible to many-to-many-relate a single model to another model more than once. Also updated the model docs to reflect this

git-svn-id: http://code.djangoproject.com/svn/django/trunk@257 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/meta.py

@@ -2049,10 +2049,11 @@ def get_manipulator_field_objs(self):
         return [formfields.IntegerField]
 
 class ManyToManyField(Field):
-    def __init__(self, to, **kwargs):
+    def __init__(self, to, rel_name=None, **kwargs):
         kwargs['name'] = kwargs.get('name', to._meta.module_name)
         kwargs['verbose_name'] = kwargs.get('verbose_name', to._meta.verbose_name_plural)
-        kwargs['rel'] = ManyToMany(to, to._meta.object_name.lower(),
+        rel_name = rel_name or to._meta.object_name.lower()
+        kwargs['rel'] = ManyToMany(to, rel_name,
             num_in_admin=kwargs.pop('num_in_admin', 0),
             related_name=kwargs.pop('related_name', None),
             filter_interface=kwargs.pop('filter_interface', None),

docs/model-api.txt

@@ -455,12 +455,17 @@ Field Types
 
     Many-to-many relations are a bit different from other fields.  First, they
     aren't actually a field per se, because they use a intermediary join table.
-    Second, they don't take any of the same options as the rest of the fields.
-    The only arguments taken are:
+    Second, they don't take the same options as the rest of the fields. The
+    only arguments taken are:
 
     =======================  ============================================================
     Argument                 Description
     =======================  ============================================================
+    ``rel_name``             Use this if you have more than one
+                             ``ManyToOneField`` s in the same model that relate
+                             to the same model. Django will use ``rel_name`` in
+                             the generated API.
+
     ``related_name``         See the description of ``related_name`` in
                              ``ManyToOneField``, above.
 
@@ -471,7 +476,19 @@ Field Types
                              should the interface be stacked horizontally or
                              vertically).
 
-    ``limit_choices_to``     See the description under ``ManyToOneField``, above.
+    ``limit_choices_to``     See the description under ``ManyToOneField`` above.
+
+    ``name``                 An alphanumeric name for the relationship. If this
+                             isn't provided, Django uses the ``module_name`` of
+                             the related object.
+
+                             This is only really useful when you have a single
+                             object that relates to the same object more than
+                             once.
+
+    ``verbose_name``         A human-readable name for the object, singular. If
+                             this isn't provided, Django uses the
+                             ``verbose_name`` for the related object.
     =======================  ============================================================
 
 ``NullBooleanField``