#8576: Multiple AutoFields in a model
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Reporter: honeyman | Owner: nobody
Status: new | Milestone:
Component: Database wrapper | Version: SVN
Keywords: | Stage: Unreviewed
Has_patch: 1 |
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Got the assertions failed recently:
File "C:\Projects\houserules\www\hrdb\events\hrpercustomerobject.py",
line 14, in <module>
class HRPerCustomerObject(models.Model):
File "C:\Projects\houserules\www\hrdb\events\hrpercustomerobject.py",
line 37, in HRPerCustomerObject
id_percustomer = models.AutoField ( 'Per-customer ID' )
File "C:\Projects\houserules\www\django\db\models\fields\__init__.py",
line 425, in __init__
assert kwargs.get('primary_key', False) is True, "%ss must have
primary_key=True." % self.__class__.__name__
AssertionError: AutoFields must have primary_key=True.
make: *** [_reset] Error 1
and
File "C:\Projects\houserules\www\django\db\models\options.py", line 117,
in _prepare
model.add_to_class('id', auto)
File "C:\Projects\houserules\www\django\db\models\base.py", line 139, in
add_to_class
value.contribute_to_class(cls, name)
File "C:\Projects\houserules\www\django\db\models\fields\__init__.py",
line 459, in contribute_to_class
assert not cls._meta.has_auto_field, "A model can't have more than one
AutoField."
AssertionError: A model can't have more than one AutoField.
make: *** [_reset] Error 1
Depending on the logic and the scenario, it may be really worthy to have
several AutoFields in a model (for example, when one or both of them in
some cases is controlled manually), one of which will definitely not be a
primary key.
I roughly described one of possible scenarios in
[http://oebfare.com/logger/django/2008/08/26/ IRC], though this may be not
the only one.
Please note that the databases itself do not imply such behaviour
(auto_increment field in MySQL does not imply a primary key, neither
SERIAL field in PostgreSQL does), so it is unsafe and overrestrictive to
add such a limitation in Django.
The existing documentation on AutoField also does not imply it should be
used for primary keys only.
My proposal is to withdraw such a limitation; seems that it is only
required to remove two assert lines from the code�(well, and the related
tests, of course).
--
Ticket URL: <http://code.djangoproject.com/ticket/8576>
Django Code <http://code.djangoproject.com/>
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