Transfer-me

It is an API designed to perform internal transfers between digital bank accounts. This application allows you to: create an account, list accounts, consult the account balance, be authenticated and make transfers to other accounts.

Based on Clean architecture

transfer-me/
┣ app/
┃ ┣ domain/
┃ ┃  ┣ account/
┃ ┃  ┣ authentication/
┃ ┃  ┣ entities/
┃ ┃  ┣ transfer/
┃ ┃  ┗ vos/
┃ ┗ gateways/
┃    ┣ db/
┃    ┗ http/
┣ cmd/
┃  ┗ main
┗ Dockerfile

Project Overview

Endpoints

Create Accounts

Create an account

Request

• Path: /accounts
• Method: POST
• Request body

  {
    "name": "gopher",
    "cpf": "12345678910",
    "secret": "mySecret"
  }

Response successful

• 201 Created

    {
      "id": "7f3412f2-97cd-46de-afa5-35f72f34f3d3",
      "name": "gopher"
    }

Response error

• 400 Bad Request

  • When request body has invalid fields

      {
        "error": "invalid cpf"
      }

  • When request body has invalid field types

      {
        "error": "invalid request payload"
      }

  • When body is empty

      {
        "error": "invalid fields"
      }

  • When account already exist

      {
        "error": "account already exist"
      }

List Accounts

Get the list of accounts

Request

• Path: /accounts
• Method: GET

Response successful

• 200 OK

    {
      "id": "7f3412f2-97cd-46de-afa5-35f72f34f3d3",
      "name": "gopher",
      "cpf": "12345678910"
    }

Response error

• 500 Internal server error

    {
      "error": "something went wrong"
    }

Get Balance

Get account balance

Request

• Path: /accounts/{account_id}/balance
• Method: GET

Response successful

• 200 OK

    {
      "balance": 100
    }

Response errors

• 404 Not Found

    {
      "error": "not found"
    }

• 500 Internal server error

    {
      "error": "something went wrong"
    }

Login

Authenticate the user with jwt token

Request

• Path: /login
• Method: POST
• Request body:

  {
    "cpf": "12345678910",
    "secret": "mySecret"
  }

Response successful

• 201 Created

    {
      "Token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE2MzA5NTI5MjQsImlhdCI6MTYzMDk1MjAyNCwiaWQiOiI5OTRmZDJhOC1kMjJmLTQ2OTMtYWVkYS00Zjk1YmQ4MjIwMjUiLCJpc3MiOiJKV1QiLCJuYW1lIjoiZ29waGVyIiwic3ViIjoiODI0MmU4NWYtYzRhZS00MzY5LWI1Y2YtNTFmNWNlZjlmMzMwIn0.PYcE5gnv7qCBn153HMVnU0lAN7kI95YnugKmqNVhQU0"
    }

Response errors

• 400 Bad Request

  • When the name or password is incorrect

     {
       "error":  "incorrect username or password"
     }

  • When request body has invalid field types

      {
        "error": "invalid request payload"
      }

  • When body is empty

      {
        "error": "invalid fields"
      }

• 500 Internal server error

    {
      "error": "unexpected error"
    }

Create Transfers

Transfers from one Account to another.

Request

• Path: /transfers
• Method: POST
• Request body:

  {
    "account_destination_id" : "7f3412f2-97cd-46de-afa5-35f72f34f3d3",
    "amount": 30
  }

• Header Params:

  {
    "Authorization" : "Bearer Token"
  }

• 201 Created

    {
      "id": "7f3412f2-97cd-46de-afa5-35f72f34f3d3"
    }

Response errors

• 400 Bad Request

  • When authorization header is empty

      {
        "error": "empty authorization header"
      }

  • When access token is empty

      {
        "error": "empty token"
      }

  • When the authentication method is wrong

      {
        "error": "invalid auth method"
      }

  • When request body has invalid field types

      {
        "error": "invalid request payload"
      }

  • When request body is empty

      {
        "error": "invalid fields"
      }

  • When destination cpf is not found

      {
        "error": "invalid transfer data"
      }

  • When amount is invalid

      {
        "error": "the amount must be greater than zero"
      }

• 403 Forbidden

    {
      "error": "invalid token"
    }

• 500 Internal server error

    {
      "error": "something went wrong"
    }

List Transfers

Get the list of transfers from the authenticated user.

Request

• Path: http://localhost:8000/transfers

• Method: GET

• 200 OK

    {
      "id": "7f3412f2-97cd-46de-afa5-35f72f34f3d3",
      "amount": 50,
      "account_origin_id": "014918d1-577c-4045-a415-a325bee3b1bd",
      "account_destination_id": "6a00ac20-e07f-455f-a53c-37088c7b4277",
      "created_at": "2021-09-23T11:20:55.774779-03:00"
    }

Response error

• 500 Internal server error

    {
      "error": "something went wrong"
    }

Environment variables

The existing environment variables in the application are listed below followed by their descriptions:

Name	Description
ACCESS_SECRET	sign key to generate jwt
API_PORT	port to start application
DB_USER	database user
DB_PASSWORD	database secret
DB_NAME	database name
DB_HOST	database host
DB_PORT	database port
DB_SSLMODE	database SSL mode
LOG_LEVEL	application structured log level

Stack

• golang (1.16.5)
• docker
• testify
• validator
• jwt
• migrate
• uuid
• mux
• pgx
• zerolog
• crypto

To download it with Go previously downloaded:

$ go mod download

Starting (Docker required)

You can use the makefile to make it easier to build and run the application. A typical day to day would be:

$  make postgres

$  make createdb

$  make build (local)

$  make build-image (docker)

$  make run

$  make test

Hands On with Moq

We're using moq to mock use cases.

How to use:

1. Indicate the interface you want to mock inserting a "//go:generate" instruction inside the code, like this:

package account

//go:generate moq -stub -out use_case_mock.go . UseCase

type UseCase interface {
	Method1() error
	Method2(i int)
}

2. Run go generate indicating the location of the interface you want to mock, like this:

go generate ./app/domain/account/usecase.go

Unit Tests

Run the command:

$  make test

To see the coverage run the command at the root of the project:

$ go test -cover ./...

License

MIT

Acknowledgments

Special thanks to all the authors of the libraries we use and the contents, videos and articles, on which I based this application. Thanks also to my mentors and code reviewers.