keogh/loanpro-code-challenge-backend

LoanPro Challenge Backend

This is a REST API in Django which provides the endpoints to create and manage arithmetic operations.

You need to have user credentials in order to use this API. Also, the user needs to have enough balance since each operation has a cost.

This API is consumed by the LoanPro Challange Frontend project.

Installation

The author of this project likes to work with Poetry to manage packages and dependencies when working with python

Python

You need python 3.11+ to run this project.

Your could use pyenv to install and manage server versions of python https://github.com/pyenv/pyenv

Once you have python you will need Poetry.

Poetry is a requirement

Install Poetry

https://python-poetry.org/docs/#installation

Activate Poetry Virtual Environment

poetry shell

install dependencies

poetry install

Setup ENV variables.

Copy the .env.example file to .env

cp .env.example .env

Set the keys with the proper values. You can get your RANDOM_ORG_API_KEY by creating an account in https://www.random.org/

The default database used in development is SQLite 3, you could configure a postgresql connection if you want to, just uncomment and set the proper values for your database configuration, e.g. if you want to use postgres

DATABASE_URL=
DB_ENGINE=django.db.backends.postgresql
DB_NAME=loanpro
DB_USER=postgres
DB_PASSWORD=password
DB_HOST=localhost
DB_PORT=5432

You could check how to connect to other databases in Django Documentation.

Django Setup

Now we need to some initial setup for django like running migrations and creating the superuser

Run migrations. Remember all commands are run through Poetry.

poetry run python manage.py migrate

Create superuser.

python manage.py createsuperuser

Usage

All endpoints, except /api/v1/sign-in, need a valid jwt token in the Authorization header or the request will be rejected.

Sign-in and use Token

First of all we need the token by sending the login credentials to /api/v1/sign-in as a POST request

curl -k -X POST -H "Content-Type: application/json" -d '{"username": "testuser", "password": "123qweasd"}' h
ttp://127.0.0.1:8000/api/v1/sign-in

Now you could fetch the records

curl -X GET -H "Authorization: TOKEN" http://127.0.0.1:8000/api/v1/records?page=2&per_page=40

If you are here with no issues then you have the backend all setup, up and running.

That's it!

API Documentation

You can find a public postman workspace here: Postman workspace

The public availability will be removed soon.

Sign-in

POST /api/v1/sign-in

Returns the jwtoken if username and password are valid.

The sample data inserted in the migrations has two users:

• testuser/123qweasd, user with over 1k records
• tesuser2/123qweasd, user with balance equals to 1

Body:

{
  "username": "testuser",
  "password": "123qweasd"
}

Response:

{
  "token": "ey...9.ey...0.D-K...k0"
}

Sign-out

POST /api/v1/sign-out

Set the token to a blocklist so it cannot be used.

Response:

{"message": "Signed out successfully"}

List Records

GET /api/v1/records

Returns the current user records paginated by default to 100 items per page, order by id in DESC direction.

Query params:

{
  "page": 1,
  "per_page": 100,
  "search": "",
  "sort_by": "id",
  "direction": "desc"
}

Response:

{
  "success": true,
  "pagination": {
    "page": "1",
    "per_page": "10",
    "total_pages": 100,
    "total_items": 1000
  },
  "records": [
    {
      "id": 1000,
      "operation_id": 5,
      "operation_type": "Square Root",
      "user_id": 1,
      "amount": 4,
      "user_balance": 2357,
      "operation_response": "5",
      "created_at": "2024-04-20 01:36:17"
    }
  ]
}

New Record

POST /api/v1/records

Creates a new Record for an arithmetic operation.

It returns insufficient balance if balance is less than the operation cost.

Body:

{
    "operation_id": 6,
    "operator1": 32,
    "operator2": 2
}

Response:

{
    "success": true,
    "record_id": 1186,
    "user_balance": 2313
}

If error you el get a httpcode and an error message:

{
  "error": "insufficient balance"
}

Delete Record

DELETE /api/v1/records/:id

Delete the record based on the ID. The record needs to belong to the user in order to be deleted.

Response:

{
    "success": true,
    "message": "Record deleted successfully, user balances records updated"
}

List Operations

GET /api/v1/operations

Returns all the available arithmetic operations and their cost.

It supports pagination and sorting just like GET /api/v1/records endpoint.

Query params

{
  "page": 1,
  "per_page": 100,
  "sort_by": "id",
  "direction": "desc"
}

Response:

{
    "success": true,
    "operations": [
        {
            "id": 6,
            "name": "Random String",
            "type": "random_string",
            "cost": 8
        },
        {
            "id": 5,
            "name": "Square Root",
            "type": "square_root",
            "cost": 4
        }
    ],
    "pagination": {
        "page": 1,
        "per_page": 10,
        "total_pages": 1,
        "total_items": 6
    }
}