Challenge Money

A REST API service for managing customer accounts and financial transactions.

Tech Stack

• Language: Go 1.25.3
• Web Framework: chi v5
• Database: PostgreSQL 18.0
• Database Driver: pgx/v5
• Validation: validator/v10
• Containerization: Docker Compose

Project Structure

challenge-money/
├── internal/
│   ├── account/          # Account domain logic
│   │   ├── handler.go
│   │   ├── models.go
│   │   ├── repository.go
│   │   └── handler_test.go
│   ├── transaction/      # Transaction domain logic
│   │   ├── handler.go
│   │   ├── models.go
│   │   ├── repository.go
│   │   └── handler_test.go
│   ├── health/           # Health check handlers
│   ├── database/         # Database connection utilities
│   └── httperrors/       # Custom HTTP error handling
├── main.go               # Application entry point
├── init.sql              # Database schema and seed data
├── docker-compose.yaml   # PostgreSQL container setup
├── Makefile              # Build and development tasks
└── run                   # Quick start script

Getting Started

Prerequisites

• Go 1.25.3 or later
• Docker and Docker Compose
• (Optional) Air for live reload during development

Installation

1. Clone the repository:

git clone https://github.com/rikw22/challenge-money
cd challenge-money

2. Install dependencies:

go mod download

3. (Optional) Install Air for live reload:

go install github.com/air-verse/air@latest

Running the Application

Quick Start

Use the provided run script:

./run

This will:

• Start PostgreSQL container via docker-compose
• Initialize the database with schema and seed data
• Start the API server with live reload (if Air is installed)

Alternative Methods

Using Makefile:

make run

Manual setup:

# Start PostgreSQL
docker compose up -d

# Run the application
go run main.go

The server will start on http://localhost:8080 by default.

API Endpoints

Postman Collection

https://github.com/rikw22/challenge-money/raw/refs/heads/main/docs/postman_collection.json

Http Client Collection

https://raw.githubusercontent.com/rikw22/challenge-money/refs/heads/main/docs/requests.http

Health Check

curl http://localhost:8080/health

Response (200 OK):

{
  "status": "UP"
}

Create Account

curl -X POST http://localhost:8080/accounts \
  -H "Content-Type: application/json" \
  -d '{
    "document_number": "12345678901"
  }'

Response (201 Created):

{
  "account_id": 1,
  "document_number": "12345678901"
}

Get Account

curl http://localhost:8080/accounts/1

Response (200 OK):

{
  "account_id": 1,
  "document_number": "12345678901",
  "created_at": "2025-10-27T00:18:14Z"
}

Create Transaction

curl -X POST http://localhost:8080/transactions \
  -H "Content-Type: application/json" \
  -d '{
    "account_id": 1,
    "operation_type_id": 4,
    "amount": 123.45
  }'

Operation Types:

• 1 - Normal Purchase (negative amount)
• 2 - Purchase with installments (negative amount)
• 3 - Withdrawal (negative amount)
• 4 - Credit Voucher (positive amount)

Response (201 Created):

{
  "id": "019a096b-ad9f-7f0e-88a4-9c93a754b029",
  "account_id": 1,
  "operation_type_id": 4,
  "amount": 123.45
}

Database Schema

Connection Details

When using docker compose:

• Host: localhost
• Port: 5432
• Database: postgres
• User: postgres
• Password: postgres

Testing

Run all tests:

make test
# or
go test ./...

Run tests with coverage:

make test-coverage
# or
go test -coverprofile=coverage.out ./...
go tool cover -html=coverage.out

Development

Building the Application

make build
# or
go build

Docker Commands

# Start PostgreSQL
make docker-up

# Stop PostgreSQL
make docker-down

Environment Variables

Variable	Description	Default
PORT	Server port	8080
DATABASE_URL	PostgreSQL connection string	postgresql://postgres:postgres@localhost:5432/postgres?sslmode=disable

Future Improvements

• Idempotence handling for transactions
• Graceful Shutdown - https://github.com/go-chi/chi/blob/master/_examples/graceful/main.go
• Integration tests
• Database migrations (e.g., golang-migrate, goose)
• API documentation (Swagger/OpenAPI)
• Rate limiting
• Authentication and authorization
• Audit logging
• Transaction rollback mechanisms
• Balance calculation and tracking