On Dec 7, 12:22 am, Continuation <selforgani...@gmail.com> wrote:
> I have:
>
> class MyModel(models.Model):
> fk = models.ForeignKey(AnotherModel)
> field = models.PositiveIntegerField()
>
> class MyForm((forms.ModelForm):
> class Meta:
> model = MyModel
>
> Now I want to create a form to edit an existing MyModel instance. But
> I don't know the pk of the instance. However I do now the value of fk
> & field, which together should be enough to uniquely identify an
> instance.
>
> So I do:
> z = MyModel.objects.get(fk=o, field=f)
> f = MyForm(instance=z)
>
> And the form f does have the correct data of z pre-populated.
>
> However when I submitted the form, a new MyModel object was created
> instead of just updating z.
>
> What do I need to do to create a form that would update z?
You don't need to do anything. If you've correctly passed in the
instance, it will always edit the existing one. I imagine that you've
used the instance when creating the form on GET, but have forgotten to
do so when creating it on POST:
f = MyForm(request.POST, instance=z)
--
DR.
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