ModelMultipleCommaField

gistfile1.py

class ModelMultipleCommaField(forms.ModelMultipleChoiceField):
    widget = forms.TextInput

    def __init__(self, queryset, db_lookup_field='pk', *args, **kwargs):
        super(ModelMultipleCommaField, self).__init__(queryset, *args, **kwargs)
        self.db_lookup_field = db_lookup_field


    def clean(self,value):
        if self.required and not value:
            raise ValidationError(self.error_messages['required'])
        elif not self.required and not value:
            return []

        values=[x.strip() for x in value.split(',')]

        if not isinstance(values, (list, tuple)):
            raise ValidationError(self.error_messages['list'])

        for value in values:
            try:
                self.queryset.filter(**{self.db_lookup_field:values})
            except ValueError:
                raise ValidationError(self.error_messages['invalid_choice'] % value)

        qs = self.queryset.filter(**{self.db_lookup_field+'__in':values})
        existing_values = set([
            force_unicode(getattr(o, self.db_lookup_field)) for o in qs
        ])
        for val in values:
            if force_unicode(val) not in existing_values:
                raise ValidationError(self.error_messages['invalid_choice'] % val)
        return qs