Django小技巧15: 使用基于类视图的Mixins

class FormMessageMixin(object):
    @property
    def form_valid_message(self):
        return NotImplemented

    form_invalid_message = 'Please correct the errors below.'

    def form_valid(self, form):
        messages.success(self.request, self.form_valid_message)
        return super(FormMessageMixin, self).form_valid(form)

    def form_invalid(self, form):
        messages.error(self.request, self.form_invalid_message)
        return super(FormMessageMixin, self).form_invalid(form)


class DocumentCreateView(FormMessageMixin, CreateView):
    model = Document
    fields = ('name', 'file')
    success_url = reverse_lazy('documents')
    form_valid_message = 'The document was successfully created!'

class DocumentUpdateView(FormMessageMixin, UpdateView):
    model = Document
    fields = ('name', )
    success_url = reverse_lazy('documents')
    form_valid_message = 'The document was successfully updated!'
    form_invalid_message = 'There are some errors in the form below.'

class DocumentUpdateView(LoginRequiredMixin, FormMessageMixin, UpdateView):
    model = Document
    fields = ('name', )
    success_url = reverse_lazy('documents')
    form_valid_message = 'The document was successfully updated!'