ModelForm save fails - django

Question

I am trying to save a modelform that represents a bank account but I keep getting a ValueError even though the form appears to validate. The models I have to use are:
class Person(models.Model):
name = models.CharField()
class Bank(models.Model):
bsb = models.CharField()
bank_name = models.CharField()
def __unicode__(self):
return '%s - %s', (self.bank_name, self.bsb)
def _get_list_item(self):
return self.id, self
list_item = property(-get_list_item)
class BankAccount(models.Model):
bank = models.ForignKey(Bank)
account_name = models.CharField()
account_number = models.CharField()
class PersonBankAcc(models.Model):
person = models.ForeignKey(Person)
The ModelForm for the personBankAcc;
def PersonBankAccForm(forms.ModelForm):
bank = forms.ChoiceField(widget=SelectWithPop)
class Meta:
model = PersonBankAcct
exclude = ['person']
def __init__(self, *args, **kwargs):
super(PersonBankAccForm, self).__init__(*args, **kwargs)
bank_choices = [bank.list_item for banks in Bank.objects.all()]
bank_choices.isert(0,('','------'))
self.fields['bank'].choices = bank_choices
The view is:
def editPersonBankAcc(request, personBankAcc_id=0):
personBankAcc = get_object_or_404(PersonBankAcc, pk=personBankAcc_id)
if request.method == 'POST':
form = PersonBankAccForm(request.POST, instance=personBankAcc )
if form.is_valid():
print 'form is valid'
form.save()
return HttpResponseRedirect('editPerson/' + personBankAcc.person.id +'/')
else:
form = PersonBankAccForm(instance=personBankAcc )
return render_to_response('editPersonBankAcc', {'form': form})
When I try to save the form I get the a VlaueError exception even though it gets passed the form.is_valid() check, the error I get is:
Cannot assign "u'26'": PersonBankAcc.bank must be a "bank" instance
I know the issue is arising because of the widget I am using in the PersonBankAccForm:
bank = forms.ChoiceField(widget=SelectWithPop)
because if I remove it it works. But all that does is gives me the ability to add a new bank to the database via a popup and then inserts it into the select list, similar to the admin popup forms. I have checked the database and the new bank is added. But it fails even if I don't change anything, if I call the form and submit it, I get the same error.
I don't understand why it does not fail at the is_valid check.
Any help would be greatly appreciated.
Thanks
Andrew

Answer 1

better yet, i don't think it really needs to be in the init function...
def PersonBankAccForm(forms.ModelForm):
bank = forms.ModelChoiceField(queryset=Bank.objects.all(),widget=SelectWithPop(),empty_label='-----')
class Meta:
model = EmpBankAcct
exclude = ['person']
def __init__(self, *args, **kwargs):
super(PersonBankAccForm, self).__init__(*args, **kwargs)