Hello Dan,
I'm not aware of any third party library handling this but a simple way to
achieve
what you're after would be to subclass ModelForm in order to override save()
and pass commit=False in your super() call.
e.g. (untested)
class UpdateFieldsModelForm(ModelForm):
update_fields = None
def save(self, commit=True):
instance = super().save(commit=False)
if commit:
update_fields = None if instance._state.adding else
self.update_fields
instance.save(update_fields=self.update_fields)
return instance
Cheers,
Simon
Le mardi 18 juin 2019 11:38:53 UTC-4, Dan Davis a écrit :
>
> So, I recently observed that a Django ModelForm updates all columns when
> it is updating a model instance. This is appropriate for a typical
> situation where Django is also in control of the schema.
> I also see that you can control this behavior by passing update_fields
> <https://docs.djangoproject.com/en/2.2/ref/models/instances/#saving-objects>
> to the save method, in a particular form:
>
> self.instance.save(update_fields=self.changed_data)
>
> I have some complicated forms that have non-model fields and many-to-many
> fields mixed in there. I'm wondering whether there is a module for Django
> out there that gives me some base ModelForms that do not update all fields,
> but only changed fields. I am asking because I don't want to work hard to
> handle corner cases if there's something already out there. What I
> already have is hard-coded to the form where I've made this change to do
> only a limited update.
>
> Thanks,
>
> -Dan
>
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