NOT NULL constraint failed when save ModelForm - django

Question

I am new in Django (1.9)
I have a NOT NULL constraint failed when I save my ModelForm and i don't understand why ...
I propose to the user a form to post a comment and the only field include in the form is "text", i want to set the excluded fields in my view after the validation and before save in database
Models.py :
class Commentaire(models.Model):
text = RichTextField()
pub_date = models.DateTimeField()
author = models.ForeignKey(User)
post = models.ForeignKey(Post)
publish = models.BooleanField()
def __str__(self):
return "/%s/%s" % (self.pub_date,self.author.username)
class Meta:
ordering = ["-pub_date"]
Forms.py :
class CommentaireForm(forms.ModelForm):
class Meta:
model = Commentaire
fields = ['text']
Views.py :
class PostDetail(View):
def get(self, request, *args, **kwargs):
view = PostDisplay.as_view()
return view(request, *args, **kwargs)
def post(self, request, *args, **kwargs):
view = PostComment.as_view()
return view(request, *args, **kwargs)
class PostDisplay(DetailView):
model = Post
def get_context_data(self, **kwargs):
context = super(PostDisplay, self).get_context_data(**kwargs)
context['form'] = CommentaireForm()
return context
class PostComment(SingleObjectMixin, FormView):
template_name = 'blogengine/post_detail.html'
form_class = CommentaireForm
model = Post
def post(self, request, *args, **kwargs):
#if not request.user.is_authenticated():
# return HttpResponseForbidden()
self.object = self.get_object()
form = self.get_form()
if form.is_valid():
return self.form_valid(form)
else:
return self.form_invalid(form)
def form_valid(self, form):
"""
If the form is valid, redirect to the supplied URL
"""
form.save(commit=False)
form.post = self.object
form.author = self.request.user
form.pub_date = datetime.now()
form.publish = True
form.save()
return HttpResponseRedirect(self.get_success_url())
When Django save the form, i have this exception :
NOT NULL constraint failed: blogengine_commentaire.pub_date
The values i set for the excluded fields (author, post, pub_date) in "form_valid" are not taken into account, they seem to stay NULL
Could you explain me why because i am lost ?
Thanks

Answer 1

You need to rewrite form_valid method like that
def form_valid(self, form):
"""
If the form is valid, redirect to the supplied URL
"""
model_instance = form.save(commit=False)
model_instance.post = self.object
model_instance.author = self.request.user
model_instance.pub_date = datetime.now()
model_instance.publish = True
model_instance.save()
return HttpResponseRedirect(self.get_success_url())
Because save(commit=False) will return you an Post instance that you then need to populate and save.