Question

So I have a modelform which I use with a modelformset factory.

If I leave the form class like this, I receive no error:

class CheckinForm(ModelForm):

class Meta:
    model = Checkout
    fields = ('return_date', )


def __init__(self, *args, **kwargs):
    super(CheckinForm, self).__init__(*args, **kwargs)
    self.fields['return_date'].widget = CheckboxInput()

If I add another field, extension to thefields, I get (1048, "Column 'book_id' cannot be null"), BUT, the changes are saved to the database.

Here is my model:

class Checkout(models.Model):
book = models.ForeignKey(Book)
user = models.ForeignKey(User)
checkout_date = models.DateField(auto_now_add = True)
return_date = models.DateField(null = True, blank=True)
extension = models.IntegerField("Extension in days", blank = True, default = 0)

and here is the view that handles the form:

def checkin(request):
c = RequestContext(request, dictionary)
CheckinFormSet = modelformset_factory(Checkout, CheckinForm)
if request.method == "POST":
    data = request.POST.copy()
    for i in range(0, int(data['form-TOTAL_FORMS'])):
        if 'form-' + str(i) + '-return_date' in data:
            data['form-' + str(i) + '-return_date'] = datetime.date.today().isoformat()
        else:
            data['form-' + str(i) + '-return_date'] = ''

    formset = CheckinFormSet(data = data)
    user_form = AutoUserForm(data = data)
    if formset.is_valid():
        c['cool'] = 'cool'
        formset.save()
    else:
        c['err'] = formset.errors
        c['data'] = data
else:
    CheckinFormSet = modelformset_factory(Checkout, CheckinForm)
    user_form = AutoUserForm()
c['user_form'] = user_form
c['form'] = CheckinFormSet
c['context'] = 'checkin'
return render_to_response('lib_admin/checkin.html', {}, c)

I have to go through the form data because for the return_date field I just have a checkbox that the user will tick, and it’ll insert the current date.

This seems really weird to me, especially because the data is saved, even though I receive the IntegrityError.

Answer 1

It isn’t a good idea to use blank=True together with default. It either has value (default) or not (blank), but not both in the same time.

Solution:

extension = models.IntegerField("Extension in days", default=0)