Django view: get_context_data() vs get()

We can do this in Django:

class LoginView(generic.FormView):

    def get_context_data(self, **kwargs):
        common = CommonView(self, **kwargs)
        context = super(LoginView, self).get_context_data(**kwargs)
        context['common'] = common.infos

or:

class LoginView(generic.FormView):

    def get(self, request, *args, **kwargs):
        common = CommonView(self, **kwargs)
        return render(request, self.template_name, {'common': common.infos })

Which one is better and why?