Let's add the course models to the administration site. Edit the admin.py file inside the courses application directory and add the following code to it:

from django.contrib import admin
from .models import Subject, Course, Module

@admin.register(Subject)
class SubjectAdmin(admin.ModelAdmin):
    list_display = ['title', 'slug']
    prepopulated_fields = {'slug': ('title',)}

class ModuleInline(admin.StackedInline):
    model = Module

@admin.register(Course)
class CourseAdmin(admin.ModelAdmin):
    list_display = ['title', 'subject', 'created']
    list_filter = ['created', 'subject']
    search_fields = ['title', 'overview']
    prepopulated_fields = {'slug': ('title',)}
    inlines = [ModuleInline]

The models for the course application are now registered in the administration site. Remember, we use the @admin.register() decorator to register models in the administration site.