Django: empty form errors

Question

I've been experiencing a little problem when I try to update some record from database. Strange thing is that form.errors are empty if form is invalid (I can't understand why).

Here are the

form

class PetitionUpdateForm(forms.ModelForm):
  owner = forms.ModelChoiceField(
    label=_('Petition creator'),
    queryset=User.objects.all(),
    widget=forms.HiddenInput()
  )

  class Meta:
    fields = ('title', 'petition_text', 'description',
              'category', 'num_signs', 'date_to', 'owner',)
    model = Petition

model

class Petition(models.Model):
  PETITION_STATUSES = (
    ('N', _('New petition')), # New one
    ('M', _('Moderation')),   # On moderation
    ('R', _('Rejected')),     # Failed petition
    ('S', _('Success'))       # Succeeded petition
  )

  title = models.CharField(max_length=512)
  slug = models.SlugField(max_length=512, editable=False, blank=True)
  description = models.TextField()
  petition_text = models.TextField(blank=True, null=True)
  petition_picture = models.ImageField(upload_to=get_upload_path, blank=True)
  petitioning = models.ManyToManyField(PetitionTarget, editable=False)
  signs = models.ManyToManyField(User, editable=False, related_name='petition_signs')
  num_signs = models.IntegerField(max_length=11, default=100, blank=True)
  category = models.ForeignKey(Category, blank=True, null=True, related_name='petition_category')
  date_to = models.DateTimeField(blank=True, null=True)

  videos = models.ManyToManyField(Video, editable=False)
  photos = models.ManyToManyField(Photo, editable=False)
  audios = models.ManyToManyField(Audio, editable=False)
  documents = models.ManyToManyField(Document, editable=False)

  created = models.DateTimeField(auto_now_add=True, editable=False)
  changed = models.DateTimeField(auto_now=True, editable=False)
  status = models.CharField(max_length=1, choices=PETITION_STATUSES, default='M', blank=True)
  owner = models.ForeignKey(User, related_name='petition_owner')

  def __unicode__(self):
    return u'{0}: {1}'.format(_('Petition'), self.title)

update view

@login_required
@render_to('petition/edit-petition.html')
def update_petition(request, slug):
  p = get_object_or_404(Petition, slug=slug)
  form = PetitionUpdateForm(request.POST or None, instance=p)
  import pdb
  pdb.set_trace()
  if form.is_valid():
    form.save()
    messages.success(request, _('Petition saved'))
  else:
    print form.errors # errors are empty
    messages.success(request, _('Some error happened'))

  return {'form': form, 'petition': p}

What's wrong with my code?

I've already tried to set null attributes for the most of model fields, switched from class based view to a standard view and yet I'm unable to update my record.

Sultan,

Thanks

Answer 1

If there is no POST data, then request.POST or None is None, so the form is unbound.

Unbound forms are always invalid, but do not have any errors.

In your case, you may want to change the else: clause to elif request.POST:

See the docs on bound and unbound forms for more details.