Payment System

This is my first project in my Golang learning journey. It implements a simple payment system where you can create and process payments using QR codes.

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Features

The API exposes the following endpoints:

/users

• GET / → Returns all users.

/user

• GET /:id → Returns user filtered by parameter id.
• POST / → Creates a new user.
  • Body:

  {
    "name": "string(required)", 
    "cpf": "string(required)", 
    "balance": "float,(required)",
    "city": "string(required)"
  }

• PUT /:id/balance → Updates user's balance.
  • Body:

  {
    "diff": "float(required)"
  }

  • A positive value deposits money into the account, and a negative value withdraws from it.
• DELETE /:id → Deletes user by the given parameter id.

/payments

• GET / → Returns all payments.
• GET /:user_id/:user_type → Returns all payments for the given user_id and user_type (receiver_id or payer_id)
  • Passing receiver_id returns received payments (deposits).
  • Passing payer_id returns sent payments (withdrawals).

/payment

• GET /:id → Returns a specific payment filtered by id.
• POST / → Creates a new payment with a QR code.
  • Body:

   {
     "receiver_id": "string(required)",
     "amount": "float(optional)`"
   }

  • If you don't provide amount, it creates a QR code payment without a fixed value. In that case, you must provide an amount when processing the payment (see endpoint below).
  • To make it simple, it uses the user's cpf as pix key.
• POST /:user_id/pay → Processes a payment by transferring money from one account to another and marking it as paid.
  • Body:

  {
    "qr_code_data": "string(required)",
    "amount": "float(optional)`"
  }

  • In user_id, you must provide the ID of the user who is making the payment (payer_id).
  • If the 15-minute processing time limit has elapsed, the payment will not be processed and will be marked as expired.
  • If something goes wrong, it will be marked as failed.
  • The program will get TransactionAmount from the QR code. If the QR code has no predefined value, you must provide an amount in the request body for the payment to be processed.
• DELETE /:id → Deletes payment by the given parameter id.

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Tech Stack

• Database: SQLite
• Backend: Go (Golang)
• Frontend: Vanila Javascript

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Running the Project

Make sure you have Go installed. Then run:

go run main.go

By default, the server will start on port 8080 and will create database in the project repository.

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Testing the API

You can interact with the project in two ways:

• Frontend: The frontend part is very simple and was created only to make testing the API easier. Access http://localhost:8080 in your browser to interact with it.

• API: Use Postman, curl, or any HTTP client to test the API directly. Example:

  curl http://localhost:8080/payments

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Automated Tests

This project includes automated tests. Make sure the server is running on port 8080, then run:

go test tests/payment_test.go

Note: You must delete any pre-created database file for the tests to run correctly.