On Apr 13, 7:25 pm, gordyt <gor...@gmail.com> wrote: > Howdy Folks, > > I have been testing model inheritance using models that have UUIDField > primary keys. It appears that when you save a new instance of a child > model, the framework is not calling get_db_prep_value() to convert the > UUIDField to a proper format before querying the parent entry. > > Let's say we have two very simple models: > > class Person(models.Model): > id = UUIDField(primary_key=True) > name = models.CharField(max_length=32) > > class Child(Person): > grade = models.SmallIntegerField() > > If you do this... > > c = Child(name="Mary", grade=5) > c.save() > > ...the framework will first create the myapp_person entry. Then it > does a query like this: > > SELECT (1) AS "a" FROM "myapp_child" WHERE > "myapp_child"."person_ptr_id" = %s > > I put some print statement in all of the methods in UUIDField, and > none of them are being called before that statement is executed, > including: get_db_prep_lookup, get_db_prep_value, get_db_prep_save, > pre_save > > The result is an error from the database: > > <class 'psycopg2.ProgrammingError'>: can't adapt > > Interesting note... the psycopg driver doesn't generate an error. > Even though it is an older driver, apparently is is less picky about > the parameters. Psycopg will accept a uuid object in the statement > that fails and apperently psycopg2 wants it cast to a string. > > If anyone has an idea I would love to hear it. > > By the way, I'm using a modified version of the UUIDField from the > django-extensions project. This is one that uses a native uuid field > for the database when the backend supports it (postgresql) and a > charfield when the backend doesn't support it (others). I did some > tests and performance with postgresql is better with the native type > (not suprising). > > --gordon
I suspect you have not set the subclass's metaclass to models.SubfieldBase - see here: http://docs.djangoproject.com/en/dev/howto/custom-model-fields/#the-subfieldbase-metaclass You need to do this to get any of the overridden methods to be called. -- DR. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
