[patch] method_save() empty value fix

[alberto@…]

Hi,

I've found a bug in django.core.meta in function method_save which would create SQL statementes with an empty value such as name= when updating. Those queries would fail (postgresql and mysql). Here is a patch. It fixed my problem but I haven't tested it very thoroughly so typical discalimers apply :). Probably can be done better so feel free to improve.

Great software, I'm so happy to have an excuse to improve my Python skills....

*** django/core/meta/__init__.py.orig   2005-09-13 17:34:54.591722120 +0200
--- django/core/meta/__init__.py        2005-09-13 17:31:55.037018584 +0200
***************
*** 782,787 ****
--- 782,793 ----
          # If it does already exist, do an UPDATE.
          if cursor.fetchone():
              db_values = [f.get_db_prep_save(f.pre_save(getattr(self, f.column), False)) for f in non_pks]
+             while 1:
+                 try: 
+                     idx = db_values.index('')
+                     non_pks[idx:idx+1] = []
+                     db_values[idx:idx+1] = []
+                 except: break
              cursor.execute("UPDATE %s SET %s WHERE %s=%%s" % (opts.db_table,
                  ','.join(['%s=%%s' % f.column for f in non_pks]), opts.pk.column), db_values + [pk_val])
          else:

[robert@…]

This also occured in my project.
The situation is an update form for an item that has edit_inline=meta.TABULAR for a field.
This means that field gets no form field (which I'm not sure is good), but is still included in non_pks.
I'm not sure how this works in the admin view.

I'm not sure about this fix. I think the right fix is to make sure that only fields that are on the page get put in the non_pks array. This means defining what effect all the edit_inline stuff has, because at the moment it is extremely vague.

[rjwittams]

I think I've found the real fix here. ​http://code.djangoproject.com/browser/django/branches/new-admin/django/core/meta/fields.py#l641

It adds a db_prep_save method to ForeignKeys. If this happens with other fields, please post about it here , they need a db_prep_save method.

Basically, empty values from POST were just being shoved in as strings rather than None which ends up being NULL in the db.

[rjwittams]

This should be fixed in the new-admin merge.