init-setup.md

To start from the beginning, including initializing a Go module for your project, here's a step-by-step guide:

1. Initialize the Go Module

First, create your project directory and navigate to it:

mkdir my-go-project
cd my-go-project

Then, initialize a Go module:

go mod init github.com/your-username/my-go-project

This command creates a go.mod file that tracks your dependencies and module versions. Replace github.com/your-username/my-go-project with your actual project path.

2. Set Up Your Folder Structure

Organize your project folder. You can follow this structure:

my-go-project/
├── db/
│   ├── migrations/       # SQL migration files go here
├── cmd/
│   └── main.go           # Entry point for your app
├── go.mod                # Go module file
└── go.sum                # Dependencies and their versions

3. Install Dependencies

Install necessary libraries for routing, ORM, and database migrations:

# Install GORM and the required database driver (PostgreSQL here)
go get -u gorm.io/gorm
go get -u gorm.io/driver/postgres

# Install golang-migrate library for migrations
go get -u github.com/golang-migrate/migrate/v4

# Install Chi router (or use another router like Gorilla Mux)
go get -u github.com/go-chi/chi/v5

4. Create a Migration File

Before you start coding, you'll need to create migration files that contain the SQL queries to set up your database tables.

Install the golang-migrate CLI if you haven't already:

brew install golang-migrate

Then create a migration file for your schema:

migrate create -ext sql -dir db/migrations -seq create_users_table

5. Set Up Your Code

Example main.go (Entry Point):

This file contains the routing setup and GORM initialization.

package main

import (
    "log"
    "net/http"
    "gorm.io/driver/postgres"
    "gorm.io/gorm"
    "github.com/go-chi/chi/v5"
)

func main() {
    // Set up the database connection
    dsn := "host=localhost user=my_user password=my_password dbname=my_db port=5432 sslmode=disable"
    db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
    if err != nil {
        log.Fatal("failed to connect to database:", err)
    }

    // Auto-migrate your schema (optional)
    db.AutoMigrate(&User{})

    // Set up the router
    r := chi.NewRouter()
    
    // Define routes
    r.Get("/", func(w http.ResponseWriter, r *http.Request) {
        w.Write([]byte("Hello, world!"))
    })

    log.Println("Starting server on :8080")
    http.ListenAndServe(":8080", r)
}

// GORM model for the 'users' table
type User struct {
    ID        uint   `gorm:"primaryKey"`
    Name      string `gorm:"size:255;not null"`
    Email     string `gorm:"size:255;unique;not null"`
}

6. Generate Migrations

Now that your schema is set up in code, you can generate SQL migration files.

1. Create the SQL migration files using golang-migrate (if not already done):

   migrate create -ext sql -dir db/migrations -seq create_users_table

2. Fill the generated migration files:

   • db/migrations/000001_create_users_table.up.sql

     CREATE TABLE users (
         id SERIAL PRIMARY KEY,
         name VARCHAR(255) NOT NULL,
         email VARCHAR(255) UNIQUE NOT NULL,
         created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
         updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
     );

   • db/migrations/000001_create_users_table.down.sql

     DROP TABLE IF EXISTS users;

7. Run Migrations

To apply the migrations and initialize your database schema:

migrate -database "postgres://user:password@localhost:5432/my_db?sslmode=disable" -path db/migrations up

8. Running the Application

To start your Go application:

go run cmd/main.go

This will start the server, auto-migrate the database (if you enabled auto-migration), and serve the API.

9. Testing the Server

Visit http://localhost:8080 in your browser or use curl to test:

curl http://localhost:8080

This should return a "Hello, world!" response.

With this setup, you now have a Go project with initialized migrations, database connections, and routing ready for backend API development.