To build our social network application, we need to store data. We
store data in a database using Django Models. These models are defined
in models.py
Here we create 3 models:
Profile - stores data about a User such as their username and picture
Post - an individual post on our social network. Posts are simply a
string of text associated with a Profile
Vote - an upvote on a Post: any Profile can add a Vote associated with
any Post

We want to add our new models to the Django admin site so that we can
start to create, edit, and delete models before we finish implementing
the rest of the our API.
Once you add these lines, go to the admin interface and see that they
were added! http://localhost:8000/admin

Create a Django REST Framework Serializer class for Post objects.
This allows us to create/read/update/list/delete Posts in our database.

At this point we don't have a simple way to actually run this code, but
in the next task we'll add API endpoints to actually use our
PostSerializer class

In the last task, we added a serializer to convert Posts to and from
our API representations.

After adding the code in this task, use your favorite REST interface
(such as
Postman) to try some requests on http://localhost:8000/api/posts - at
this point we've implemented support for listing all posts (GET to
/api/posts), creating a post (POST to /api/posts), getting an
individual post by ID (GET to /api/posts/<id>), updating a post (PUT to
/api/posts/<id>) and deleting a post (DELETE to /api/posts/<id>)

As you might have noticed, that's a lot of code to do not a whole lot.
Fortunately Django REST Framework provides a lot of conveniences for us
that we'll explore in later tasks.