GO Bookstore REST API

A hands-on learning project for building RESTful APIs with Go. This bookstore API is built from scratch using Gorilla Mux for routing and GORM with MySQL as the data layer, covering the full lifecycle of an HTTP request from route registration to database persistence.

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Table of Contents

• Overview
• Learning Goals
• Tech Stack
• Project Structure
• Prerequisites
• Getting Started
• Database
• Response Format

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Overview

This project is a hands-on exploration of building REST APIs in Go without a heavy framework. It implements a simple bookstore service with endpoints for creating and listing books, structured following real-world conventions: a dedicated entry point, separated routing/controller/model layers, a centralised database configuration package, and a shared response type.

The goal is to understand how all the pieces of a Go web service fit together — from registering routes with Gorilla Mux, to decoding JSON request bodies, to persisting data through GORM's ORM layer.

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Learning Goals

This project was built to practise and solidify the following concepts:

• Go module system — understanding go.mod, dependency management with go mod tidy/download
• HTTP routing — using Gorilla Mux to define method-specific routes
• Controller pattern — separating HTTP handler logic from business/data logic
• ORM with GORM — defining models, running AutoMigrate, and performing CRUD operations
• MySQL integration — connecting Go to a relational database via a DSN string
• JSON encoding/decoding — reading request bodies with json.NewDecoder and writing responses with json.NewEncoder
• Package organisation — structuring a Go project across multiple packages (config, models, controller, routes, type)
• Consistent API responses — defining a shared Response struct as a typed JSON envelope

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Tech Stack

Technology	Purpose
Go 1.20	Core language
Gorilla Mux	HTTP router & dispatcher
GORM	ORM / database abstraction
MySQL	Relational database

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Project Structure

GO-Learn_REST/
├── cmd/
│   └── main.go               # Application entry point
├── pkg/
│   ├── config/
│   │   └── db.go             # Database connection & configuration
│   ├── controller/
│   │   ├── book-controller.go # HTTP handler functions
│   │   └── index.go
│   ├── models/
│   │   └── book-model.go     # Book model & database operations
│   ├── routes/
│   │   ├── book-routes.go    # Route definitions
│   │   └── index.go
│   └── type/
│       └── index.go          # Shared response types
├── go.mod
└── go.sum

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Prerequisites

• Go 1.20+
• MySQL 8.0+

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Getting Started

1. Clone the repository

git clone https://github.com/SeanardK/GO-REST_API.git
cd GO-REST_API

2. Set up the database

Create the MySQL database before running the application:

CREATE DATABASE `go-bookstore`;

The application connects to root@127.0.0.1:3306/go-bookstore by default. Update the DSN in pkg/config/db.go if your credentials differ.

3. Install dependencies

go mod download

4. Run the server

go run cmd/main.go

The server starts on http://localhost:3001.

GORM will automatically migrate the books table on startup via AutoMigrate.

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Database

The application connects to a local MySQL instance using the following default DSN:

root@tcp(127.0.0.1:3306)/go-bookstore

To use a different user, password, or host, update the Connect() function in pkg/config/db.go:

gorm.Open(mysql.Open("user:password@tcp(host:port)/go-bookstore"))

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Response Format

All endpoints return a consistent JSON envelope:

{
  "message": "string",
  "status": 200,
  "data": []
}

Field	Type	Description
message	string	Human-readable status message
status	integer	HTTP-style status code
data	array	Array of book objects