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Code Issues 32 Releases Wiki Activity

Added a db_constraint option to ForeignKeys.

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This controls whether or not a database level cosntraint is created. This is useful in a few specialized circumstances, but in general should not be used!
This commit is contained in:
Alex Gaynor
2013-02-20 11:27:32 -08:00
parent cb5545ea2d
commit b55cde054e
6 changed files with 57 additions and 8 deletions
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13
docs/ref/models/fields.txt
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@@ -1051,6 +1051,19 @@ define the details of how the relation works.
The field on the related object that the relation is to. By default, Django
uses the primary key of the related object.
.. attribute:: ForeignKey.db_constraint
Controls whether or not a constraint should be created in the database for
this foreign key. The default is ``True``, and that's almost certainly what
you want; setting this to ``False`` can be very bad for data integrity.
That said, here are some scenarios where you might want to do this:
* You have legacy data that is not valid.
* You're sharding your database.
If you use this, accessing a related object that doesn't exist will raise
its ``DoesNotExist`` exception.
.. attribute:: ForeignKey.on_delete
When an object referenced by a :class:`ForeignKey` is deleted, Django by