On Tue, 2009-09-22 at 08:13 -0700, PlanetUnknown wrote:
> I'm sure I'm missing something simple here, since its a common flow -
>
> 1.) e.g. model Person - has 4 fields -
> person_id = models.AutoField(primary_key=True)
> person_name = models.CharField(max_length=50)
> comments = models.TextField(blank=True)
> create_dt = models.DateTimeField(auto_now_add=True)
> modify_dt = models.DateTimeField(auto_now_add=True)
> class Meta:
> unique_together = ("person_id", "person_name")
>
> 2.) When I save a new person, everything works normal, since I'm
> giving -
> p1 = Person(person_id=None, person_name=personNameArg,
> comments=pComment)
>
> 3.) After this save is performed, I have the "person_id" of this
> person. When someone hits save again, I do this -
>
> p1 = Person(person_id=personIdArg, person_name=personNameArg,
> comments=pComment)
> where personIdArg is the earlier saved id.
>
> I get the error - "create_dt cannot be Null", I see that dJango is
> correctly trying to update, but since I didn't pass create_dt, it is
> setting it to NULL in the update query.
>
> I just want it to be left alone, since it already has a value. Is
> there a way to tell django to not touch these fields ?
>
> Thanks!
It isn't that common; I haven't got that in any of my views.
The canonical way to update an item, AFAICT, is like so:
foo = Foo.objects.get(pk=foo_id)
foo.field = new_value
foo.save()
Cheers
Tom
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