06.GORMv2

# 01.gorm基础

# 1.1 安装

go get -u gorm.io/gorm
go get -u gorm.io/driver/sqlite

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# 1.2 增删改查

package main

import (
	"gorm.io/driver/mysql"
	"gorm.io/gorm"
)

type Product struct {
	gorm.Model
	Code  string
	Price uint
}

func main() {
	dsn := "root:1@tcp(127.0.0.1:3306)/m_test?charset=utf8mb4&parseTime=True&loc=Local"
	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})
	if err != nil {
		panic("failed to connect database")
	}

	// 1、迁移 schema
	db.AutoMigrate(&Product{})

	// 2、增
	db.Create(&Product{Code: "D42", Price: 100})

	// 3、读
	var product Product
	db.First(&product, 1)                 // 根据整形主键查找
	db.First(&product, "code = ?", "D42") // 查找 code 字段值为 D42 的记录

	// 4、改
	db.Model(&product).Update("Price", 200)
	//// Update - 更新多个字段
	//db.Model(&product).Updates(Product{Price: 200, Code: "F42"}) // 仅更新非零值字段
	//db.Model(&product).Updates(map[string]interface{}{"Price": 200, "Code": "F42"})

	// 5、删
	db.Delete(&product, 1)
}

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# 02.模型定义

# 2.1 定义模型

type User struct {
  ID           uint
  Name         string
  Email        *string
  Age          uint8
  Birthday     *time.Time
  MemberNumber sql.NullString
  ActivedAt    sql.NullTime
  CreatedAt    time.Time
  UpdatedAt    time.Time
}

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# 2.2 gorm.Model

GORM 定义一个 gorm.Model 结构体，其包括字段 ID、CreatedAt、UpdatedAt、DeletedAt

// gorm.Model 的定义
type Model struct {
  ID        uint           `gorm:"primaryKey"`
  CreatedAt time.Time
  UpdatedAt time.Time
  DeletedAt gorm.DeletedAt `gorm:"index"`
}

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# 03.gorm基本使用

├── main.go
├── models
│   ├── core.go
│   ├── curd.go
│   └── user.go

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# 3.1 mian.go

package main

import (
	"gorm_learn/models"
)

func main() {
	models.InitConn()
	// 迁移 schema
	// models.DB.AutoMigrate(&models.User{})
	models.AddUser()
}

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# 3.2 models/core.go

package models

import (
	"gorm.io/driver/mysql"
	"gorm.io/gorm"
)

var DB *gorm.DB
var err error

func InitConn() {
	dsn := "root:1@tcp(127.0.0.1:3306)/m_test?charset=utf8mb4&parseTime=True&loc=Local"
	DB, err = gorm.Open(mysql.Open(dsn), &gorm.Config{})
	if err != nil {
		panic("gorm conn err")
	}
}

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# 3.3 model/user.go

package models

type User struct {
	Id       int
	Username string
	Age      int
	Email    string
	AddTime  int
}

//定义结构体操作的数据库表
func (User) TableName() string {
	return "user"
}

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# 3.4 model/curd.go

package models

import "time"

// 1、增
func AddUser() {
	user := User{
		Username: "zhangsan",
		Age:      26,
		Email:    "zhangsan.qq.com",
		AddTime:  int(time.Now().Unix()),
	}
	DB.Create(&user)
}

// 2、查
func SelectUser() {
	user := []User{}
	DB.Find(&user)
}

// 3、改
func UserEdit() {
	//1、查找username=zhangsan
	user := User{Username: "zhangsan"}
	DB.First(&user)

	//2、执行修改为 lisi
	user.Username = "lisi"
	DB.Save(&user)
}

// 4、删
func UserDel() {
	DB.Where("username = ?", "zhangsan").Delete(&User{})
}

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# 04.锁

package main

import (
	"fmt"
	"gorm.io/gorm"
	"gorm_learn/models"
)

func main() {
	models.InitConn()
	column := models.DB.Model(&models.User{}).Where("id", 43).UpdateColumn("username", "wangwu")
	fmt.Println(column.RowsAffected)
	if column.RowsAffected == 0 {
		fmt.Println("未作修改")
	}
}

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上次更新: 2024/3/13 15:35:10

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