URL not found for updateview with polymorphic models and forms in Django

Question

I am trying to display all the models that are related to another model in a modal box when a user clicks on a button. However, the Update view is not working how I want it to work. I am getting a Not Found for the URL pattern related to the class based view (Model Object UpdateView) instead of 200 OK

I tried several approaches, but below is the latest one. When I do a print out of the get_queryset (that I have override), I get the objects. I tried to print the context['formset'], but it seems like the code didn't reach that far.

I am using django-bootstrap-modal-forms 1.4.2 to display model formsets and I am using django-polymorphic 2.1.2 to deal with polymorphism of the models. The reason why I am using this approach are: 1. There is a many to many relationships between a modelflow and a model object. 2. Using the modal box would make a cleaner interface, instead of have both the modelflow and modelobject on the same page. 3. I want to have the polymorphic approach deals with the objects that is related to a modelflow.

models.py - There are two main models that are polymorphic models ModelFlow & ModelObject along with their sub-classes.

class ModelFlow(PolymorphicModel):
    decription = models.CharField(max_length=250)
    relatedModelObject = models.ManyToManyField('ModelObject', through='ModelFlowObject', null=True, blank=True)

class ModelBFlow(ModelFlow):
    modelflGroup = models.ForeignKey(BasicFlowGroup, on_delete=models.CASCADE, null=True, blank=True)


class ModelAFlow(ModelFlow):
    modelflGroup = models.ForeignKey(BoundedFlowGroup, on_delete=models.CASCADE, null=True, blank=True)


class ModelObject(PolymorphicModel):
    objectName = models.CharField(max_length=250)

class ModelFlowObject(PolymorphicModel):
    flowModel = models.ForeignKey(ModelFlow, on_delete=models.CASCADE)
    objectModel = models.ForeignKey(ModelObject, on_delete=models.CASCADE)

class WebPageObject(ModelObject):
    objectValue = models.CharField(max_length=3, choices=WEBPAGEVALUE_CHOICES)

class LinkObject(ModelObject):
    paramType = models.CharField(max_length=3, choices=WEBPAGEVALUE_CHOICES)
    linkType = models.CharField(max_length=3, choices=WEBPAGEVALUE_CHOICES)

forms.py - I create the two forms based on the WebPageObject & LinkObject both inherits from ModelObject (a polymorphic model) I then created a polymorphic modelformset.

class ModelWebPageObjectForm(ModelForm):
      class Meta:
        model = WebPageObject
        fields='__all__'

class ModelLinkObjectForm(ModelForm):
    class Meta:
        model = LinkObject
        fields = '__all__'

Oformset = polymorphic_modelformset_factory(ModelObject,formset_children=(                                                      
PolymorphicFormSetChild(WebPageObject, form=ModelWebPageObjectForm, fields = '__all__'),), fields='__all__',extra=1)
PolymorphicFormSetChild(LinkObject, form=ModelLinkObjectForm, fields = '__all__'),

views.py - In this view, I have a used the ModelObject (a polymorphic model) as the model for the updateview. I then created a form_class with model/form pairs

class DisplayModelFlow(Updateview):
   ....
   #this view is already working. It displays all the modelflow that is related to another model. Here I am using inlineformset. 

class ModelObjectUpdateView(BSModalUpdateView):
    #in this view the self.kwargs['pkObj'] from the urls.py will be used to get the modelflow object. Next, modelflow is used to find the all the modelobject (webpage or link) that are related to this. So, I am using a polymorphic modelformset to display all the modelobjects in the modal box.
    model=ModelObject
    form_class = {WebPageObject:ModelWebPageObjectForm,
                  LinkObject:ModelLinkObjectForm,
    }
    template_name = 'modalPopUp/updateModelObject.html'
    success_message = 'Success: Object(s) Updated.'

    def get_form_class(self):
        return self.form_class[self.object.__class__]

    '''def get_object(self):
        flowmodel=ModelFlow.objects.filter(id=self.kwargs['pkObj'])
        return flowmodel[0]'''

    def get_queryset(self):
        flowmodel=ModelFlow.objects.filter(id=self.kwargs['pkObj'])
        myobj=flowmodel[0].relatedModelObject.all()
        return myobj

    def get_context_data(self, **kwargs):
        context = super(ModelObjectUpdateView, self).get_context_data(**kwargs)
        if self.request.POST:
            context['formset'] = Oformset(queryset=self.get_queryset())
        else:
            context['formset'] = Oformset(queryset=self.get_queryset())
        return context

    def post(self, request, *args, **kwargs):
        formset = Oformset(self.request.POST)
        if (formset.is_valid()):
            return self.form_valid(formset)
        else:
            return self.form_invalid(formset)

    def form_valid(self, formset):
        self.object = formset.save()
        return HttpResponseRedirect(self.get_success_url())

    def form_invalid(self, formset):
        return self.render_to_response(self.get_context_data(formset=formset))

    def get_success_url(self):
        self.success_url = reverse_lazy('recSys:FlowRecSysList', kwargs={'project': self.kwargs['project'],
                                                                         'useCaseName': self.kwargs['useCasename']})
        return self.success_url

urls.py - This is the url updateview gets.

...
path('<str:project>/UCModelUpdate/<int:pk>/updateModelObject/<str:pkObj>', ModelObjectUpdateView.as_view(), name='updateModelObject'),
...

template

There is a .html to display the modelFlow along with a button that when is clicked displays the modal box for the objects will be displayed. There may be several modelFlows on the .html along with a button for the modal box that should display only the modelobjects that are related to it.

The expected result should be a modal box with the all the allows based on the queryset in the context['formset']. Also, GET should be 200 OK.

However, I am getting this message: Not Found: /useCaseExtract/Marvel-E-Store/UCModelUpdate/2/updateModelObject/319/ [15/Sep/2019 12:26:41] "GET /useCaseExtract/Marvel-E-Store/UCModelUpdate/2/updateModelObject/319/ HTTP/1.1" 404 5459 and no modal box is being displayed.