Question

I am working with modelformset, and am a little stuck. I am passing, say 20 forms using modelformsetfactory. These forms are constructed and displayed in the page. When I return after the posting, I only want some of these forms to be validated and saved, not all of them, depending upon the value of a model field.

I figured I could use queryset in the request.POST to limit the forms that I want in my formset that are to be validated. But this is not working. Is there any way I can limit the number of forms?

For the queryset that limits model instances I tried

formset = PaymentOptionFormSet(request.POST, queryset=payment_option_posted_queryset)

I get the following error:

IndexError at /seller/seller_profile/

list index out of range


Traceback:
File "/home/shagun/work/tinla/django/core/handlers/base.py" in get_response
  100.                     response = callback(request, *callback_args, **callback_kwargs)
File "/home/shagun/work/tinla/web/views/user_views.py" in seller_profile
  164.             formset = PaymentOptionFormSet(request.POST, queryset=payment_option_posted_queryset)           
File "/home/shagun/work/tinla/orders/forms.py" in __init__
  400.         super(BasePaymentOptionFormSet, self).__init__(*args,**kwargs)
File "/home/shagun/work/tinla/django/forms/models.py" in __init__
  423.         super(BaseModelFormSet, self).__init__(**defaults)
File "/home/shagun/work/tinla/django/forms/formsets.py" in __init__
  47.         self._construct_forms()
File "/home/shagun/work/tinla/django/forms/formsets.py" in _construct_forms
  97.             self.forms.append(self._construct_form(i))
File "/home/shagun/work/tinla/django/forms/models.py" in _construct_form
  447.             kwargs['instance'] = self.get_queryset()[i]
File "/home/shagun/work/tinla/django/db/models/query.py" in __getitem__
  172.             return self._result_cache[k]

Exception Type: IndexError at /seller/seller_profile/
Exception Value: list index out of range

My code looks like this:

def seller_profile(request):
    from accounts.models import PaymentOption, PaymentMode
    payment_options = PaymentOption.objects.select_related('payment_mode').filter(payment_mode__client__id=1)
    payment_option_queryset = PaymentOption.objects.filter(payment_mode__client__id='1')
    payment_option_posted_queryset = PaymentOption.objects.filter(payment_mode__client__id='1', is_active='1')

    if request.user.is_authenticated():

        PaymentOptionFormSet = modelformset_factory(PaymentOption, formset = BasePaymentOptionFormSet, extra=0, fields = ("payment_delivery_address", "bank_branch", "bank_ac_name", "bank_ac_type", "bank_ac_no", "bank_address", "bank_ifsc", "is_active"))
        user = request.user.get_profile()
        if request.method == "POST":#If the form has been submitted
            form1 = SellerProfileForm(request.POST, instance = user)
            form2 = SellerNotificationForm(request.POST, instance = user)
            formset = PaymentOptionFormSet(request.POST, queryset=PaymentOption.objects.all())

            counting = 0
            for form in formset.forms:
                counting +=1
            print "count = ",counting
            print formset.is_valid()
            if form1.is_valid() and form2.is_valid:
                form1.save()
                form2.save()
            else:
                my_acct_ctxt = getMyAccountContext(request)
                return render_to_response('seller/seller_profile.html',
                {
                    'form1': form1,
                    'form2': form2,
                    'formset': formset,
                    'error1': form1.errors,
                    'error2': form2.errors,
                    'errorformset': formset.errors,
                    'payment_options': payment_options,
                    'acc': my_acct_ctxt,
                },
                context_instance=RequestContext(request))

        else: #If the form has not been submitted 
            form1 = SellerProfileForm(instance = user)
            form2 = SellerNotificationForm(instance = user)
            formset = PaymentOptionFormSet(queryset=payment_option_queryset)
            counter = 0

        my_acct_ctxt = getMyAccountContext(request)
    return render_to_response('seller/seller_profile.html',
        {
        'form1': form1,
        'form2': form2,
        'formset': formset,
        'payment_options': payment_options,
        'acc':my_acct_ctxt,
        },
        context_instance=RequestContext(request))

Answer 1

If you’re needing to conditionally validate a formset, you can override the clean method of the formset. Here’s an example of how I’ve done this within admin on an inline formset, which you can probably change to suit your needs as the Formset classes are pretty homogenous.

class MyInlineFormset(forms.models.BaseInlineFormSet):
    def clean(self):
        for form in self.forms:
            try:
                if form.cleaned_data:
                    delete = form.cleaned_data.get('DELETE')
                    if not delete:
                        my_field = form.cleaned_data.get('my_field', None)
                        if my_field:
                            if my_field == 'some_value':
                              #only validate the other values
                              #if the field you're looking for
                              #has a particular value, etc
                              another_field = form.cleaned_data.get('another_field')

                              #more validation here where you can raise
                              #forms.ValidationError()

            except AttributeError:
                pass

I hope that helps you out!