Fixed #8788: fixed a few typoes in [8805]. Thanks, Matthew Flanagan and mir.

            except FieldDoesNotExist:

                # This is an extra field that's not on the ModelForm, ignore it

                continue

            # MySQL can't handle ... WHERE pk IS NULL, so make sure we don't 

            # MySQL can't handle ... WHERE pk IS NULL, so make sure we

            # don't generate queries of that form.

            is_null_pk = f.primary_key and self.cleaned_data[name] is None

            if name in self.cleaned_data and f.unique and not is_null_pk:

            if self.instance.pk is not None:

                qs = qs.exclude(pk=self.instance.pk)

            # This cute trick with extra/values is the most efficiant way to

            # This cute trick with extra/values is the most efficient way to

            # tell if a particular query returns any results.

            if qs.extra(select={'a': 1}).values('a').order_by():

                model_name = capfirst(self.instance._meta.verbose_name)

Overriding the clean() method

-----------------------------

You can overide the ``clean()`` method on a model form to provide additional

You can override the ``clean()`` method on a model form to provide additional

validation in the same way you can on a normal form. However, by default the

``clean()`` method validates the uniqueness of fields that are marked as unique

on the model, and those marked as unque_together, if you would like to overide

the ``clean()`` method and maintain the default validation you must call the

or unique_together on the model. Therefore, if you would like to override

the ``clean()`` method and maintain the default validation, you must call the

parent class's ``clean()`` method.

Form inheritance