On Mar 25, 9:32 am, Tom Evans <tevans...@googlemail.com> wrote:
> On Thu, Mar 25, 2010 at 5:52 AM, Kenneth Gonsalves <law...@au-kbc.org> wrote:
> > hi,
>
> > I have a model like this:
>
> > name - unique
> > slno - not null
> > mode - not null
>
> > If the instance does not exist and I give all three values to get_or_create,
> > it works
>
> > if the instance exists, and I give values for slno and mode which are
> > different
> > from the existing ones - I get a programming error as get_or_create tries to
> > create a new instance and falls foul of the unique constraint on name. It
> > works if I only give the value for name - it gets the instance and then I
> > can
> > add the new values and save
>
> > if the instance does not exist and I only give the value for name, I get a
> > programming error that the not null constraints on slno and mode are
> > violated.
>
> > so it looks to me that get_or_create will only work reliably when there are
> > no
> > not null or unique constraints in the model. Or am I missing something?
>
> I think you are missing the optional kwarg 'initial', which is a
> dictionary of initial values to use when the instance does not exist.
> So not
>
> foo, created = Foo.objects.get_or_create(name=name,
> sino=sino,mode=mode)
>
> but
>
> foo, created = Foo.objects.get_or_create(name=name,
> initial={'sino': sino, 'mode': mode, })
>
> Cheers
>
> Tom
Actually the kwarg is 'defaults', not 'initial'.
See
http://docs.djangoproject.com/en/1.1/ref/models/querysets/#get-or-create-kwargs
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DR.
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