main.go

package main

import (
	"net/http"

	"github.com/gin-gonic/gin"
	"gorm.io/driver/postgres"
	"gorm.io/gorm"
)

type Book struct {
	ID     string `json:"id" gorm:"primaryKey"`
	Title  string `json:"title"`
	Author string `json:"author"`
}

var db *gorm.DB

func Migrate(db *gorm.DB) {
	db.AutoMigrate(&Book{})
}

func connectToDb() {
	var err error
	dsn := "host=localhost user=myuser password=123 dbname=mydb port=5432 sslmode=disable"
	db, err = gorm.Open(postgres.Open(dsn), &gorm.Config{})

	if err != nil {
		panic("failed to connect to database")
	}

	Migrate(db)
}

func main() {
	connectToDb()

	router := gin.Default()

	router.GET("/books/:id", getBook)
	router.POST("/books", createBook)
	router.PUT("/books/:id", updateBook)
	router.DELETE("/books/:id", deleteBook)

	router.Run("localhost:8000")
}

func getBook(c *gin.Context) {
	id := c.Param("id")

	var book Book
	if err := db.First(&book, "id = ?", id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "book not found"})
		return
	}

	c.JSON(http.StatusOK, book)
}

func createBook(c *gin.Context) {
	var newBook Book

	if err := c.ShouldBindJSON(&newBook); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	db.Create(&newBook)
	c.JSON(http.StatusCreated, newBook)
}

func updateBook(c *gin.Context) {
	id := c.Param("id")

	var updatedBook Book
	if err := db.First(&updatedBook, "id = ?", id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "Book not found"})
		return
	}

	if err := c.ShouldBindJSON(&updatedBook); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	db.Save(&updatedBook)
	c.JSON(http.StatusOK, updatedBook)
}

func deleteBook(c *gin.Context) {
	id := c.Param("id")

	if err := db.Delete(&Book{}, "id = ?", id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "book not found"})
		return
	}

	c.JSON(http.StatusNoContent, nil)
}