Django Movie Ratings API

live application on Heroku

Django 3.0.7. rest API application for providing secure access to the movie ratings SQL data base

about me

The purpose of this application is to serve information to my front end Angular 10. I ran into difficulty when I decided to host all of my static files remotely, on AWS. having used SVG icons from a sprite library, I discovered that Django's built in security principles, wouldn't let me render them. Like most things, I discovered that there was a trick or a knack, to use JavaScript to reach out to my AWS S3 bucket instead and so render the svg icons inline via DOM model injection to my HTML mark-up.

Additional lessons learned, was how to log into and back out of the Django admin site, using my own frontend. I'll certainly be maintaining method for reaching the admin login portal for future projects! The live link above, will let one see for themselves, what I mean.

the technical stuff

If you're interested in the nuts and bolts for accessing the admin login, you can do so by updating your url patters like so:

from django.contrib.auth.views import LoginView

urlpatterns = [
    
    # add a custom admin login page
    path('login/', LoginView.as_view(),
        {'template_name': 'core/login.html'}, name='login'),
    # include logout page as home for admin on logout
    path('admin/logout/', include('home.urls')),
    # ...rest of my patterns continue
]

Here I'm referring to the built in Django LoginView as the view function then on user logout, redirecting the user to the home page. using logoutView, redirects the user to the Django's built in needed during development when there was no custom front end, but now now.

the API itself

I've used the concept, based on a tutorial by Senior Full Stack Engineer, Krystian Czekalski, then added to it for my own learning experience.

Beginning with the Models

1st we setup a Movie mode: Each movie will have a title, description and an image. Each movie will also have a rating as well as an average rating (average rating from multiple users).
2nd we setup a Ratings model: the movie is linked to the 1st model by ForeignKey the user from the authenticated User is linked by ForeignKey The number of stars given by the user out of 5, is assigned to the movie. The relationship between user and movie is unique.

Setting up the Serializer

In the simplest sense, the serializer makes sense of the Model data in JSON format objects.

This application has 3 serializers and these are the primary imports:

from rest_framework import serializers
from django.contrib.auth.models import User
from .models import Movie, Rating
from rest_framework.authtoken.models import Token

UserSerializer returns the User model data as an object. When creating a user, serializer uses rest framework to create a Token for the user. This then negates the need to pass usernames and passwords while the user interacts with the API services.

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ('id', 'username', 'password')
        # define parameters for password
        extra_kwargs = {'password': {'write_only': True, 'required': True}}

    #  create own definition to create user from built in crate_user function
    def create(self, validated_data):
        user = User.objects.create_user(**validated_data)
        # crate token for new user and add to user DB
        Token.objects.create(user=user)
        return user

Constructing the user in the database

{
    "name": "User List",
    "description": "",
    "renders": [
        "application/json",
        "text/html"
    ],
    "parses": [
        "application/json",
        "application/x-www-form-urlencoded",
        "multipart/form-data"
    ],
    "actions": {
        "POST": {
            "id": {
                "type": "integer",
                "required": false,
                "read_only": true,
                "label": "ID"
            },
            "username": {
                "type": "string",
                "required": true,
                "read_only": false,
                "label": "Username",
                "help_text": "Required. 150 characters or fewer. Letters, digits and @/./+/-/_ only.",
                "max_length": 150
            },
            "password": {
                "type": "string",
                "required": true,
                "read_only": false,
                "label": "Password",
                "max_length": 128
            }
        }
    }
}

Raw data of the user list:

[
    {
        "id": 2,
        "username": "sampleName01"
    },
    {
        "id": 1,
        "username": "sampleName02"
    },
    {
        "id": 3,
        "username": "sampleName03"
    }
]

MovieSerializer represents the model data as an object

[
    {
        "id": 1,
        "title": "Some Movie Title 1",
        "description": "movie description 1",
        "imagePath": "web-link for movie image 1",
        "no_of_ratings": 3,
        "ave_ratings": 3.6666666666666665
    },
    {
        "id": 2,
        "title": "Some Movie Title 2",
        "description": "movie description 2",
        "imagePath": "web-link for movie image 2",
        "no_of_ratings": 2,
        "ave_ratings": 3.5
    },
    {
        "id": 3,
        "title": "Some Movie Title 3",
        "description": "movie description 3",
        "imagePath": "web-link for movie image 3",
        "no_of_ratings": 1,
        "ave_ratings": 3.0
    }
]

RatingSerializer represents the model data as an object

[
    {
        "id": 1,
        "stars": 4,
        "user": 1,
        "movie": 1
    },
    {
        "id": 2,
        "stars": 2,
        "user": 2,
        "movie": 2
    },
    {
        "id": 3,
        "stars": 3,
        "user": 3,
        "movie": 1
    }
]

Each rating, links the movie to the user- the person who gave it their personal rating. If we remove one of the users, we also remove their rating. If we remove one of the movies, then the ratings for that movie from all of the different users are removed from the record.

ddeveloper72 / movieratings