Simple REST API for managing a library catalog while practicing Go back-end fundamentals: HTTP routing with net/http, request handlers, database connectivity, and CRUD workflows on top of MySQL.

• Wiring environment-driven MySQL connections (DSN via .env).
• Designing a minimal data model (models.Book).
• Implementing repository helpers for CRUD with database/sql.
• Building HTTP handlers that decode/encode JSON payloads.
• Registering method-aware routes using Go 1.22+ patterns and http.ServeMux.

cmd/api/main.go        # bootstrapper: load env, run server
internal/router        # http.ServeMux wiring
internal/handlers      # book CRUD handlers
internal/db            # DB connection + queries
internal/models        # Book struct definition

• Go 1.22+
• MySQL 8.x (or compatible)
• github.com/go-sql-driver/mysql
• github.com/joho/godotenv

1. Copy .env.example (or create a new .env) and define DSN in the Go MySQL driver format, e.g.:

   DSN="user:password@tcp(127.0.0.1:3306)/library?parseTime=true"

2. Create the books table:

   CREATE TABLE books (
     id INT AUTO_INCREMENT PRIMARY KEY,
     title VARCHAR(255) NOT NULL,
     author VARCHAR(255) NOT NULL,
     genre VARCHAR(100) NOT NULL,
     published_year INT NOT NULL,
     available BOOLEAN DEFAULT TRUE,
     created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
   );

3. Install dependencies:

   go mod tidy

go run ./cmd/api

Server listens on :8080.

curl -X POST http://localhost:8080/books \
  -H "Content-Type: application/json" \
  -d '{
        "title": "The Pragmatic Programmer",
        "author": "Andrew Hunt",
        "genre": "Tech",
        "published_year": 1999,
        "available": true
      }'

curl http://localhost:8080/books

curl http://localhost:8080/books/1

curl -X PUT http://localhost:8080/books/1 \
  -H "Content-Type: application/json" \
  -d '{
        "title": "Pragmatic Programmer (20th)",
        "author": "Andy Hunt",
        "genre": "Tech",
        "published_year": 2019,
        "available": true
      }'

curl -X DELETE http://localhost:8080/books/1

1. Add validation for request payloads (title length, year bounds).
2. Swap database/sql helpers for a repository interface + tests.
3. Add pagination/filtering to GET /books.
4. Dockerize the API and the MySQL instance for quicker setup.