Courses Platform 📝

Aproach 💡

The project includes a REST API that has been implemented in accordance with clean architecture. Leonardo Giordani's work inspired me very much during the development of this application. Especially I mean his book, which can be found here. Excellent book with very good examples, I highly recommend it.

The second source that is definitely worth mentioning here is the repository/book CosmicPython 📘.

Quickstart 📜

The fastest way to start an application is to use the Makefile. Run this command in project root directory.

make build
make up

To add the startup data to the database, just use this command:

make seed-db

To turn everything off:

make down

To run all tests, use this command:

make test

Layers 🔬

app
├── __init__.py
├── adapters
│   ├── __init__.py
│   ├── orm.py
│   ├── repositories.py
│   └── unit_of_work.py
├── application
│   ├── __init__.py
│   ├── course
│   │   ├── __init__.py
│   │   ├── commands.py
│   │   └── queries.py
│   ├── user
│   │   ├── __init__.py
│   │   ├── commands.py
│   │   └── queries.py
│   ├── interfaces
│   │   ├── __init__.py
│   │   └── iunit_of_work.py
│   └── exceptions.py
├── domain
│   ├── __init__.py
│   ├── course.py
│   └── user.py
├── response_objects
│   ├── __init__.py
│   └── responses.py
└── service
    ├── __init__.py
    ├── config.py
    ├── course
    │   ├── __init__.py
    │   ├── serializers.py
    │   └── views.py
    ├── user
    │   ├── __init__.py
    │   ├── serializers.py
    │   └── views.py
    ├── extensions.py
    ├── parser.py
    ├── schemas.py
    └── status_codes.py

Domain

---

At the domain layer, two entities have been implemented: User and Course.
As you might expect, one user can be enrolled in many courses and courses can also have many different users.

Application

---

All functionalities have been broken down into a number of independent commands and queries.

Adapters

---

The adapters that have been implemented are mainly Repository for interacting with the database and mapping objects from the database to domain objects. Additionally, the Unit of Work pattern was used here to ensure transactionality.

Service

---

The REST API was made with the very popular Flask micro-framework. It is very minimalistic and is based primarily on the application layer.

Error Management

---

Errors are raised in the application layer in specific commands and queries - this is where business rules can determine what the error really is.

Endpoints 🚀

One of the best methods for testing the APIs is HTTPie. In this section, I will use commands using exactly this CLI.

User

/api/users

---

GET - get a list of all users.

http :5000/api/users

http :5000/api/users include==courses

POST - create new user.

http POST :5000/api/users email='[email protected]'

/api/users/<user_id>

---

GET - get details of a specific user.

http :5000/api/users/123 

http :5000/api/users/123 include==courses

Sample response:

{
    "_links": {
        "collection": "/api/users",
        "courses": "/api/users/4aa841d3-a852-408e-bd3f-e23b726b8d1a/courses",
        "self": "/api/users/4aa841d3-a852-408e-bd3f-e23b726b8d1a"
    },
    "courses": [
        {
            "_links": {
                "collection": "/api/courses",
                "enroll_user": "/api/courses/3ad9b870-b752-4854-9708-4fc6b703c64d/users",
                "self": "/api/courses/3ad9b870-b752-4854-9708-4fc6b703c64d"
            },
            "id": "3ad9b870-b752-4854-9708-4fc6b703c64d",
            "name": "Test Course"
        },
        {
            "_links": {
                "collection": "/api/courses",
                "enroll_user": "/api/courses/b39fefaa-a143-475c-9b4d-751b0843aaa8/users",
                "self": "/api/courses/b39fefaa-a143-475c-9b4d-751b0843aaa8"
            },
            "id": "b39fefaa-a143-475c-9b4d-751b0843aaa8",
            "name": "Sample Course"
        }
    ],
    "email": "[email protected]",
    "id": "4aa841d3-a852-408e-bd3f-e23b726b8d1a"
}

DELETE - delete user.

http DELETE :5000/api/users/123 

/api/users/<user_id>/courses

---

GET - get a list of courses for a specific user.

http :5000/api/users/123/courses

Course

/api/courses/

---

GET - get a list of all courses.

http :5000/api/courses

http :5000/api/courses include==enrollments

POST - create new course.

http POST :5000/api/courses name='Test Course'

/api/courses/<course_id>

---

GET - get details of a specific course.

http :5000/api/courses/123

http :5000/api/courses/123 include==enrollments

Sample response:

{
    "_links": {
        "collection": "/api/courses",
        "enroll_user": "/api/courses/3ad9b870-b752-4854-9708-4fc6b703c64d/users",
        "self": "/api/courses/3ad9b870-b752-4854-9708-4fc6b703c64d"
    },
    "enrollments": [
        {
            "_links": {
                "collection": "/api/users",
                "courses": "/api/users/9c2f4dee-8db5-4045-95bb-c487d6d52e5b/courses",
                "self": "/api/users/9c2f4dee-8db5-4045-95bb-c487d6d52e5b"
            },
            "email": "[email protected]",
            "id": "9c2f4dee-8db5-4045-95bb-c487d6d52e5b"
        },
        {
            "_links": {
                "collection": "/api/users",
                "courses": "/api/users/4aa841d3-a852-408e-bd3f-e23b726b8d1a/courses",
                "self": "/api/users/4aa841d3-a852-408e-bd3f-e23b726b8d1a"
            },
            "email": "[email protected]",
            "id": "4aa841d3-a852-408e-bd3f-e23b726b8d1a"
        }
    ],
    "enrollments_count": 2,
    "id": "3ad9b870-b752-4854-9708-4fc6b703c64d",
    "name": "Test Course"
}

DELETE - delete course.

http DELETE :5000/api/courses/123

/api/courses/<course_id>/users

---

POST - enroll a user on the course.

http POST :5000/api/courses/123/users user_id=321

/api/courses/<course_id>/users/<user_id>

---

DELETE - withdraw a user enrollment from a course.

http DELETE :5000/api/courses/123/users/321

TODO 🏆

1. Add authentication layer with JWT.
2. Implement OpenAPI specification.
3. Create a K8S setup.
4. Add NGINX as a rivers proxy to the architecture.