fintech-hub / loan-fintech-api

:credit_card: :cloud: Another Loan Fintech API

Loan Fintech API with Django REST Framework

Objective

The main objective of this project is to create an API to manage the loan payments control system from a fintech.

Purpose

The purpose of this challenge is to test your ability to implement a solution given an abstract problem. You may find a problem in the asked task that you need to explain the problem and propose a solution to fix it.

Problem

A fintech needs to keep track of the amount of money loaned and the missed/made payments. It also needs a place to retrieve the volume of outstanding debt at some point in time.

Limitations

Loans are paid back in monthly installments.

Install

Setup install

• pipenv install

Running

• python manage.py makemigrations --settings=config.settings.dev
• python manage.py migrate --settings=config.settings.dev
• python manage.py test --settings=config.settings.dev
• python manage.py runserver --settings=config.settings.dev

Endpoints

• Documentatin: /swagger/
• Admin: /admin/
• Get JWT token: /api/token/
• Refresh JWT token: /api/token/refresh/
• All clients: /clients/
• Client by id: /client/{client_id}/
• All loans: /loans/
• Balance by client id: /loans/{loan_id}/balance/
• Payments by client id: /loans/{loan_id}/payments/

POST /clients/

Summary

Create a record of a client

Payload

• client_id:
• name:
• surname:
• email:
• telephone:
• cpf:

Example of sent data

{
    "client_id": 1,
    'name': 'Nome',
    'surname': 'Sobrenome',
    'email': '[e-mail]',
    'telephone': '6533245152',
    'cpf': '85478999988'
}

GET /client/

Summary

List client id

Example of sent data

{
    "client_id": 1,
}

Example of received data

{
    "client_id": 1,
    'name': 'Nome',
    'surname': 'Sobrenome',
    'email': '[e-mail]',
    'telephone': '6533245152',
    'cpf': '85478999988'
}

POST /loans

Summary

Create a loan application. Loans are automatically accepted.

Payload

• amount: loan amount in dollars.
• term: number of months that will take until the loan gets paid-off.
• rate: interest rate as decimal.
• date: when the loan was requested (origination date as an ISO 8601 string).

Example of sent data

{
    "amount": 1000,
    "term": 12,
    "rate": 0.05,
    "date": "2019-05-09 03:18Z"
}

Reply

• loan_id: unique id of the loan.
• installment: monthly loan payment.

Example of received data

{
    "loan_id": "000-0000-0000-0000"
    "installment": 85.60
}

Notes

Loan payment formula

r = rate / 12
installment = [r + r / ((1 + r) ^ term - 1)] x amount

Example

For repaying a loan of $1000 at 5% interest for 12 months, the equation would be:

installment = [(0.05 / 12) + (0.05 / 12) / ((1 + (0.05 / 12)) ^ 12 - 1] x 1000
installment = 85.60

POST /loans/<:id>/payments

Summary

Create a record of a payment made or missed.

Payload

• payment_choice: type of payment: made or missed.
• date: payment date.
• amount: amount of the payment made or missed in dollars.

Example of sent data (Payment made)

{
    "payment_choice": "made",
    "date": "2019-05-07 04:18Z",
    "amount": 85.60
}

Example of sent data (Payment missed)

{
    "payment_choice": "missed",
    "date": "2019-05-07 04:18Z",
    "amount": 85.60
}

POST /loans/<:id>/balance

Summary

Get the volume of outstanding debt (i.e., debt yet to be paid) at some point in time.

Payload

• date: loan balance until this date.

Example of sent data

{
    "date": "2017-09-05 02:18Z"
}

Reply

• balance: outstanding debt of loan.

Example

{
    "balance": 40
}