Fixed #7026 -- Fixed misleading/incorrect exception text when adding …

…to a many-to-many set on an object that doesn't yet have a primary-key value. Thanks for the report, ryan@peaceworks.ca

git-svn-id: http://code.djangoproject.com/svn/django/trunk@7622 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/fields/related.py

@@ -351,7 +351,7 @@ def __init__(self, model=None, core_filters=None, instance=None, symmetrical=Non
             self.target_col_name = target_col_name
             self._pk_val = self.instance._get_pk_val()
             if self._pk_val is None:
-                raise ValueError("%r instance needs to have a primary key value before a many-to-many relationship can be used." % model)
+                raise ValueError("%r instance needs to have a primary key value before a many-to-many relationship can be used." % instance.__class__.__name__)
 
         def get_query_set(self):
             return superclass.get_query_set(self).filter(**(self.core_filters))

tests/modeltests/many_to_many/models.py

@@ -39,6 +39,14 @@ class Meta:
 
 # Create an Article.
 >>> a1 = Article(id=None, headline='Django lets you build Web apps easily')
+
+# You can't associate it with a Publication until it's been saved.
+>>> a1.publications.add(p1)
+Traceback (most recent call last):
+...
+ValueError: 'Article' instance needs to have a primary key value before a many-to-many relationship can be used.
+
+# Save it!
 >>> a1.save()
 
 # Associate the Article with a Publication.