Displaying courses

For our course catalog, we have to build the following functionality:

• List all available courses, optionally filtered by subject
• Display a single course overview

Edit the views.py file of the courses application and add the following code:

from django.db.models import Count
from .models import Subject

class CourseListView(TemplateResponseMixin, View):
    model = Course
    template_name = 'courses/course/list.html'

    def get(self, request, subject=None):
        subjects = Subject.objects.annotate(
                       total_courses=Count('courses'))
        courses = Course.objects.annotate(
                       total_modules=Count('modules'))
        if subject:
            subject = get_object_or_404(Subject, slug=subject)
            courses = courses.filter(subject=subject)
        return self.render_to_response({'subjects...