Fixed #12510. Changed ModelChoiceField to stop using some of its superclasses implementation. This could cause more than one query when generating choices. Thanks, Petr Marhoun and Honza Kral.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12211 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/forms/models.py

@@ -903,8 +903,7 @@ class ModelChoiceField(ChoiceField):
 
     choices = property(_get_choices, ChoiceField._set_choices)
 
-    def clean(self, value):
-        Field.clean(self, value)
+    def to_python(self, value):
         if value in EMPTY_VALUES:
             return None
         try:
@@ -914,6 +913,9 @@ class ModelChoiceField(ChoiceField):
             raise ValidationError(self.error_messages['invalid_choice'])
         return value
 
+    def validate(self, value):
+        return Field.validate(self, value)
+
 class ModelMultipleChoiceField(ModelChoiceField):
     """A MultipleChoiceField whose choices are a model QuerySet."""
     widget = SelectMultiple