Override dispatch

viewmixin.py

class StudentRequiredMixin:
    def dispatch(self, request, *args, **kwargs):
        response = super().dispatch(request, *args, **kwargs)  # noqa
        if request.user.status != "étudiant":
            messages.info(
                request=request,
                message="Seuls les étudiants peuvent se pré-inscrire",
            )
            return redirect("university:detail", slug=self.kwargs.get("slug"))  # noqa
        return response


class HasAlreadyRegisterMixin:
    def dispatch(self, request, *args, **kwargs):
        response = super().dispatch(request, *args, **kwargs)  # noqa
        university = get_object_or_404(University, slug=self.kwargs.get("slug"))  # noqa
        registration = Registration.objects.filter(
            user=request.user, university=university
        ).first()
        if not registration:
            return response
        if registration.paid:
            messages.info(
                request=request,
                message="Vous etes deja inscrit a cette universite",
            )
            return redirect("university:detail", slug=university.slug)
        messages.info(
            request=request,
            message="Vous etes inscrit a cette universite, a present Il vous suffit "
                    "de payer pour valider votre preinscription a cette universite",
        )
        return redirect(
            "university:pre_registration_payment", slug=registration.slug
        )  # noqa

views.py

class RegisterView(
    LoginRequiredMixin, StudentRequiredMixin, HasAlreadyRegisterMixin, View
):
    template_name = "universities/register.html"

    def get_university(self):
        return get_object_or_404(University, slug=self.kwargs.get("slug"))

    def get_context_data(self, **kwargs):  # noqa
        return {
            "register_form": RegisterForm(prefix="register"),
            "tutor_m_form": TutorForm(prefix="tutor_m"),
            "tutor_f_form": TutorForm(prefix="tutor_f"),
        }

    def get(self, request, *args, **kwargs):
        registration = Registration.automatic_registration(
            user=request.user, university=self.get_university()
        )
        if registration:
            messages.success(
                request,
                "Vous etes a present inscrit, il vous suffit de payer pour valider votre preinscription"
                " a cette universite",
            )
            return redirect(
                "university:pre_registration_payment", slug=registration.slug
            )
        return render(request, self.template_name, self.get_context_data())