DetailView方法的参数和pk_url_kwarg的用法

Question

I'm currently watching a course on Django and wondering about the following code:

class RestaurantDetailView(DetailView):
    queryset = Restaurant.objects.all()

    def get_context_data(self, *args, **kwargs):
        context = super().get_context_data(*args, **kwargs)
        return context

    def get_object(self, *args, **kwargs):
        rest_id = self.kwargs.get('rest_id')
        obj = get_object_or_404(Restaurant, id=rest_id)
        return obj

1.) Why is the instructor of this course using *args in the get_context_data method but in the source code of django the get_context_data only has **kwargs

Source Code of get_context_data method

2.) Furthermore the get_object method. Why does he use *args and **kwargs but the method in Django only has a queryset argument

Source Code of get_object method

3.) And my last question, why isn't the just using the pk_url_kwarg variable to change the name of pk to rest_id

I rewrote this code an it still works but I'm really new to Django and I'm not sure if misunderstood something.

class RestaurantDetailView(DetailView):
    pk_url_kwarg = 'rest_id'
    queryset = Restaurant.objects.all()

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        return context

Answer 1

As a Django user, def get_context_data(self, *args, **kwargs): and def get_object(self, *args, **kwargs): look unusual to me. The code will work because the same args and kwargs are passed to super() . You could argue that it makes the code more robust because it will still work if Django changes the signature in a future version. However I would prefer to use the same signatures as the parent class.

You are correct that you could use pk_url_kwarg instead of overriding get_object . The pk_url_kwarg should be the name of the kwarg in the URL pattern, so in this case it should be pk_url_kwarg = 'rest_id' . The advantage of pk_url_kwarg is that it simplifies the code. The disadvantage is that it's less obvious how the object is being fetched if you're not familiar with Django's class-based-views.

There's a couple more changes you could make. Instead of queryset = Restaurant.objects.all() you can simply set model , because get_queryset defaults to self.model.objects.all() .

Finally, the get_context_data method doesn't do anything apart from printing, so I would remove it entirely once I'd finished debugging.

Putting that together, you get:

class RestaurantDetailView(DetailView):
    model = Restaurant
    pk_url_kwarg = 'rest_id'