Another django formset issue (initial values)

[Ofer Koren]

I'll use my previous example again.

Basically it fails because of the initial value set on the InstrumentForm.

The formset thinks the empty form as changed (as if the Instrument field was modified to the initial value), and because some other fields are required and not filled, fails validation.

I would expect supplying an 'initial' value to a field wouldn't cause the form to be regarded as modified.

Any ideas what I might be doing wrong?

# (models.py):

class InstrumentType(Model):

    name = CharField(...)

class Instrument(Model):

    auth_user = ForeignKey(User)

    instrument = ForeignKey(InstrumentType)

    model = CharField(required=True)

# (forms.py):

class InstrumentForm(django.forms.ModelForm):

    instrument = forms.ModelChoiceField(

                queryset=Instrument.objects.all(), 

                initial=Instrument.objects.get(name='guitar')

                )

    class Meta:

        model = Instrument

        exclude = ('auth_user',)

# (views.py):

InstrumentsFormSet = modelformset_factory(

                                Instrument, 

                                can_delete=True, 

                                form=InstrumentForm)

def manage_instruments_view(request):

    user_instruments = Instrument.objects.filter(auth_user=request.user)

    if request.method == "GET":

        formset = InstrumentsFormSet(queryset=user_instruments)

    elif request.method == "POST":

        formset = InstrumentsFormSet(request.POST, queryset=user_instruments)

        if formset.is_valid():       # <--------------------------- fails here

            for form in formset.forms:

                form.instance.auth_user = request.user

            instances = formset.save()

            return HttpResponseRedirect('/saved/')

        else:

            pass   # invalid data

    return direct_to_template(request, 'users/form_update_profile.html', extra_context=loca

- Ofer
www.mrbroken.com

[Meir Kriheli]

Hi,

On 02/28/2011 12:50 PM, Ofer Koren wrote:
> I'll use my previous example again.
> Basically it fails because of the initial value set on the InstrumentForm.

> The formset thinks the empty form as /changed/ (as if the Instrument
> field was /modified /to the /initial/ value), and because some other

> fields are required and not filled, fails validation.
> I would expect supplying an 'initial' value to a field wouldn't cause
> the form to be regarded as modified.
> Any ideas what I might be doing wrong?
>

Set initial during formset instantiation:

http://docs.djangoproject.com/en/dev/topics/forms/formsets/#using-initial-data-with-a-formset

Cheers
--
Meir Kriheli

>
> # (models.py):
>
> class InstrumentType(Model):
> name = CharField(...)
>
>
> class Instrument(Model):
>
> auth_user = ForeignKey(User)
> instrument = ForeignKey(InstrumentType)
> model = CharField(required=True)
>
> # (forms.py):
>
> class InstrumentForm(django.forms.ModelForm):
>

> *

> instrument = forms.ModelChoiceField(
> queryset=Instrument.objects.all(),
> initial=Instrument.objects.get(name='guitar')
> )

> *

> www.mrbroken.com <http://www.mrbroken.com>
>
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[Ofer Koren]

That is an awkward feature - it forces me to count the number of model instances in my query-set, add the number of extra forms, and then create that many initial-data-dictionaries:

myset = MyModel.objects.filter(auth_user=request.user)

formset = MyFormSet(queryset = myset, initial = [{'instrument_type':Instrument.objects.get(name='guitar')}]*(myset.count()+num_extra_forms)

- Ofer
www.mrbroken.com

[Ofer Koren]

Any other ideas?... or have I misunderstood?

- Ofer
www.mrbroken.com

[Shai Berger]

On Sunday 06 March 2011, Ofer Koren wrote:
> Any other ideas?... or have I misunderstood?
>

I think you misunderstood initial data: Forms with initial data are not
considered "empty unless something changed". An empty form is only one where
all fields are empty.

You can get the behavior you want by overriding the formset's clean() method:
http://docs.djangoproject.com/en/dev/topics/forms/formsets/#custom-formset-
validation

Shai.

[Shai Berger]

On second thought...

On Sunday 06 March 2011, Ofer Koren wrote:

> >> > # (views.py):
> >> >
> >> > InstrumentsFormSet = modelformset_factory(
> >> >
> >> > Instrument,
> >> > can_delete=True,
> >> > form=InstrumentForm)
> >> >
> >> > def manage_instruments_view(request):
> >> > user_instruments =
> >> > Instrument.objects.filter(auth_user=request.user)
> >> >
> >> > if request.method == "GET":
> >> > formset = InstrumentsFormSet(queryset=user_instruments)
> >> >
> >> > elif request.method == "POST":
> >> > formset = InstrumentsFormSet(request.POST,
> >> >
> >> > queryset=user_instruments)

Why are you passing in the queryset here?

Shai.

[Ofer Koren]

I'm basically following the django examples:

http://docs.djangoproject.com/en/dev/topics/forms/modelforms/#using-a-custom-queryset

Regarding initial-data: django seems to skip validation/saving of a form in a formset if it hasn't changed. This is determined by the 'has_changed' method, which checks the current values against the initial values. However it seems to to be buggy when the initial value is being set in the Form definition (as opposed to Formset instantiation).

- Ofer
www.mrbroken.com

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