EchoMarket - Learning Go Microservices

A simple microservices project to learn Go, REST APIs, and PostgreSQL.

What You'll Learn

• Building REST APIs in Go
• Database operations with PostgreSQL
• Layered architecture (handlers → services → repository)
• Docker basics
• Testing APIs

Project Structure

user-service/
├── main.go              # Entry point - starts the server
├── models/              # Data structures
│   └── user.go
├── database/            # Database connection
│   └── database.go
├── repository/          # Database queries
│   └── user_repository.go
├── services/            # Business logic
│   └── user_service.go
├── handlers/            # HTTP request handlers
│   └── user_handler.go
└── routes/              # URL routing
    └── routes.go

Quick Start

1. Start PostgreSQL

docker-compose up -d

2. Install Dependencies

cd user-service
go mod download

3. Run the Service

go run main.go

You should see:

🚀 Starting User Service...
✅ Database connected successfully
✅ Users table ready
✅ User Service running on http://localhost:8080

Test the API

Health Check

curl http://localhost:8080/health

Create a User

curl -X POST http://localhost:8080/users \
  -H "Content-Type: application/json" \
  -d '{"name":"Alice","email":"alice@example.com"}'

Response:

{
  "id": 1,
  "name": "Alice",
  "email": "alice@example.com",
  "created_at": "2025-01-28T12:00:00Z"
}

Get a User by ID

curl http://localhost:8080/users/1

Get All Users

curl http://localhost:8080/users

Understanding the Code Flow

When you create a user (POST /users):

1. Handler (handlers/user_handler.go)

   • Receives HTTP request
   • Parses JSON
   • Calls service layer

2. Service (services/user_service.go)

   • Validates data
   • Calls repository layer

3. Repository (repository/user_repository.go)

   • Executes SQL query
   • Returns data

4. Response flows back through the layers

What's Next?

Once you're comfortable with this:

1. Add more features

   • Update user endpoint
   • Delete user endpoint
   • Search users by email

2. Add validation

   • Email format validation
   • Duplicate email check

3. Add tests

   • Unit tests for services
   • Integration tests for handlers

4. Build a second service

   • Product service
   • Order service

Common Issues

"connection refused"

• Make sure PostgreSQL is running: docker ps
• Check if port 5432 is available

"package not found"

• Run go mod download in user-service directory

"table already exists"

• That's fine! The code handles this with IF NOT EXISTS

Learning Resources

• Go by Example - Quick Go reference
• PostgreSQL Tutorial - Learn SQL
• REST API Best Practices - API design

License

MIT