class based views -TypeError: super(type, obj): obj must be an instance or subtype of type

Question

I am building an app in Django, it uses class based views.

In my views.py I have this class based view that allows to inspect details of objects in my model Product:

class ProductDetailView(DetailView):
    queryset = Product.objects.all()
    template_name = "products/detail.html"

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

As I try to run the server I get this traceback:

Traceback (most recent call last):
...
context = super(ProductListView, self).get_context_data(*args, **kwargs)
TypeError: super(type, obj): obj must be an instance or subtype of type

What is the problem?

Answer 1

As you derived yourself, the type should be an element of the Method Resolution Order (MRO) of self, so:

class ProductDetailView(DetailView):
    queryset = Product.objects.all()
    template_name = 'products/detail.html'

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

however, since python-3.x, you do not need to pass parameter to super(): If you are using the class where it is defined, and self as parameter, you can make use of super(), so you can rewrite this to:

class ProductDetailView(DetailView):
    queryset = Product.objects.all()
    template_name = 'products/detail.html'

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

This thus makes it easy to define a code fragment that can be easily copy pasted to other views.

Furthermore here it makes no sense to override get_context_data, since you only call the super method and return its result, you can ommit the override.