Fixed #9778 -- Added some special casing of the "Join on field 'abc'" error

message. It now gives an extra hint if there's a chance you just made a typo in
the lookup type.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@9620 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/sql/query.py

@@ -1455,7 +1455,10 @@ class BaseQuery(object):
                     self.update_dupe_avoidance(dupe_opts, dupe_col, alias)
 
         if pos != len(names) - 1:
-            raise FieldError("Join on field %r not permitted." % name)
+            if pos == len(names) - 2:
+                raise FieldError("Join on field %r not permitted. Did you misspell %r for the lookup type?" % (name, names[pos + 1]))
+            else:
+                raise FieldError("Join on field %r not permitted." % name)
 
         return field, target, opts, joins, last, extra_filters
 

tests/modeltests/lookup/models.py

@@ -293,7 +293,7 @@ FieldError: Cannot resolve keyword 'pub_date_year' into field. Choices are: head
 >>> Article.objects.filter(headline__starts='Article')
 Traceback (most recent call last):
     ...
-FieldError: Join on field 'headline' not permitted.
+FieldError: Join on field 'headline' not permitted. Did you misspell 'starts' for the lookup type?
 
 # Create some articles with a bit more interesting headlines for testing field lookups:
 >>> now = datetime.now()