#11811: No error raised on update(foreignkey=unsavedobject) on nullable fk
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Reporter: Afief | Owner: ashearer
Status: assigned | Milestone: 1.2
Component: Database layer (models, ORM) | Version: 1.1
Resolution: | Keywords:
Stage: Accepted | Has_patch: 1
Needs_docs: 0 | Needs_tests: 0
Needs_better_patch: 0 |
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Changes (by ashearer):
* has_patch: 0 => 1
Comment:
The updated patch (rev-5) doesn't raise exceptions for model instances
that are never saved anyway, which fixes the multi-DB test failures.
The one remaining design issue is a backward compatibility vs. consistency
tradeoff. The patch errs on the side of backward compatibility: if the
foreign key field is declared non-null, assignment works as before, and
lets the database raise its own integrity error instead of the new
ValueError exception with a detailed error message. The queryset.update()
patch can't tell how the field is declared, though, so it always raises
ValueError. Raising ValueError in all cases would be more consistent and
probably more helpful, but it could break compatibility for code that's
already expecting to catch a particular integrity error.
Also, the patch could attempt to be smart. When it detects that the
foreign key value is missing but there is a cached instance, it could fill
the key in from that instance, in case the instance was saved after the
assignment. But that's starting to get magical, so it doesn't do that.
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Ticket URL: <http://code.djangoproject.com/ticket/11811#comment:5>
Django <http://code.djangoproject.com/>
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