views.py

class WriteReview(StudentOnlyMixin, CreateView):
    model = CourseReview
    form_class = ReviewForm
    template_name = 'academy/write_review.html'

    def dispatch(self, request, *args, **kwargs):
        # check if review exists
        try:
            course = get_object_or_404(Course, slug=self.kwargs['slug'])
            self.course = course
            old_review = CourseReview.objects.filter(author=self.request.user, course=course).first()
        except IndexError:
            pass
        else:
            return HttpResponseRedirect()

        return super(WriteReview, self).dispatch(request, *args, **kwargs)

    def get_context_data(self, **kwargs):
        context = super(WriteReview, self).get_context_data(**kwargs)
        context['course'] = get_object_or_404(Course, slug=self.kwargs['slug'])
        return context

    def form_valid(self, form):
        course = get_object_or_404(Course, slug=self.kwargs['slug'])
        form.save(commit=False)
        form.instance.course = course
        form.instance.author = self.request.user
        messages.success(self.request, 'Your review has been saved!')
        return super(WriteReview, self).form_valid(form)

    def get_success_url(self):
        return "{}?#LECTURES".format(reverse('course.landing.page', args={self.kwargs['slug']}))