Ticket #862: 862.diff

django/core/meta/__init__.py

@@ -938 +938 @@
     if not pk_set or not record_exists:
         field_names = [db.db.quote_name(f.column) for f in opts.fields if not isinstance(f, AutoField)]
         placeholders = ['%s'] * len(field_names)
-        db_values = [f.get_db_prep_save(f.pre_save(getattr(self, f.attname), True)) for f in opts.fields if not isinstance(f, AutoField)]
+        db_values = []
+        # Pre-save all values. We could do this as a one-liner, but then 
+        # it'd be near-impossible to figure out which field was causing 
+        # the problem. 
+        for f in opts.fields: 
+            if not isinstance(f, AutoField): 
+                try: 
+                    val = getattr(self, f.attname)
+                    f_presave = f.pre_save(val, True)
+                    db_presave = f.get_db_prep_save(f_presave)
+                    db_values.append(db_presave)
+                except Exception, ex: 
+                    # Append a message to the exception's arguments, 
+                    # and then re-raise it. Yes, Veronica, this works.
+                    msg = "save() can't handle field %s" % f.attname
+                    ex.args = tuple(list(ex.args)+[msg])
+                    raise
         if opts.order_with_respect_to:
             field_names.append(db.db.quote_name('_order'))
             # TODO: This assumes the database supports subqueries.