How to handle errors in "nested" forms - django

Question

I have two models:
class Building(models.Model):
label = models.CharField(_("Building label"), blank=False, max_length=255)
def get_absolute_url(self):
return reverse('buildings:config', kwargs={'pk': self.id})
class Floor(models.Model):
label = models.CharField(_("Floor label"), blank=True, max_length=255)
building = models.ForeignKey(Building, null=False)
I have written a custom ModelForm in order to allow the user to change (UpdateView) the building's infos and add a new floor (FloorsConfigForm) in the same page.
The FloorsConfigForm is :
class FloorsConfigForm(forms.ModelForm):
class Meta:
model = Floor
fields = ["label", "building",]
And the view is:
class BuildingConfigUpdateView(LoginRequiredMixin, UpdateView):
model = Building
fields = ('label','address',)
template_name = "buildings/building_update.html"
form_floors = FloorsConfigForm(prefix="floor_")
def get_context_data(self, **kwargs):
ret = super(BuildingConfigUpdateView, self).get_context_data(**kwargs)
ret["form_floors"] = self.form_floors
b = Building.objects.get(id=self.kwargs["pk"])
ret["floors"] = Floor.objects.filter(building=b)
return ret
def post(self, request, *args, **kwargs):
res = None
print(request.POST)
if "action_save" in request.POST:
res = super(BuildingConfigUpdateView, self).post(request, *args, **kwargs)
elif "action_add_floor" in request.POST:
# #add the floor , validate, save...
self.form_floors = FloorsConfigForm(request.POST, prefix="floor_")
if self.form_floors.is_valid():
self.form_floors.save()
res = HttpResponseRedirect(reverse('buildings:config', kwargs={"pk":self.kwargs["pk"]}))
else:
print(self.form_floors.errors)
res = HttpResponseRedirect(reverse('buildings:config', kwargs={"pk":self.kwargs["pk"]}))
else:
res = HttpResponseRedirect(reverse('buildings:config', kwargs={"pk":self.kwargs["pk"]}))
return res
This works very well, and I am happy(!)
BUT the last mile is to properly display the errors of my form_floors form in the template of its "parent".
And this is where I need you!
Note: in the view code above, I simply print the form error (print(self.form_floors.errors), and this is OK since it print
"<QueryDict: {'csrfmiddlewaretoken': ['gcBxn72bm6cLFXmpIatplZ0cNtsNgMlU'], 'floor_-building': [''], 'action_add_floor': [''], 'floor_-label': ['']}>
<ul class="errorlist"><li>building<ul class="errorlist"><li>This field is required.</li></ul></li></ul>"
when I dont specify a building to the floor.
The exact question is: how can I render this error message in the main template?
Edit - Getting closer
In my post def in view, I changed the Redirects:
def post(self, request, *args, **kwargs):
res = None
print(request.POST)
if "action_save" in request.POST:
res = super(BuildingConfigUpdateView, self).post(request, *args, **kwargs)
elif "action_add_floor" in request.POST:
# #add the floor , validate, save...
self.form_floors = FloorsConfigForm(request.POST, prefix="floor_")
if self.form_floors.is_valid():
self.form_floors.save()
res = HttpResponseRedirect(reverse('buildings:config', kwargs={"pk":self.kwargs["pk"]}))
else:
print(self.form_floors.errors)
res = super(BuildingConfigUpdateView, self).post(request, *args, **kwargs)
else:
res = HttpResponseRedirect(reverse('buildings:config', kwargs={"pk":self.kwargs["pk"]}))
return res
It's better, I have access to the errors in the template. But my main form is empty!
It's emplty because in my template, I have two html forms. So, when I send the second form, the POST request don't have the other kwargs.
Now, I need to find a way to "fusion" two requests!