GORM学习笔记

GORM学习笔记

官方文档：https://gorm.io/zh_CN/docs/

1、数据准备

create table student
(
    id         int auto_increment
        primary key,
    sn         varchar(20) null,
    name       varchar(20) null,
    email      varchar(20) null,
    class_id   int         null,
    monitor_id int         null
);

2、快速开始

2.1、安装依赖

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

2.2、db

package model

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

var DB *gorm.DB
var err error

// Student 属性需大写
type Student struct {
    Id        int
    Sn        string
    Name      string
    Email     string
    ClassId   int
    MonitorId int
}

func (s Student) TableName() string {
    return "student"
}

func init() {
    dsn := "root:Chace2233.@tcp(127.0.0.1:3306)/study?charset=utf8&parseTime=True&loc=Local"
    DB, err = gorm.Open(mysql.Open(dsn), &gorm.Config{})
    if err != nil {
       fmt.Println(err)
    }
    fmt.Println(DB)
}

2.3、controller

package controller

import (
	"fmt"
	"ginstudy/model"
	"github.com/gin-gonic/gin"
	"net/http"
	"strconv"
)

type StudentController struct {}

func (student StudentController) Select(c *gin.Context) {
	var users []model.Student
	// 全量查询
	//model.DB.Find(&users)
	// 条件查询
	model.DB.Where("id<6").Find(&users)
	c.JSON(http.StatusOK, users)
}

func (student StudentController) Insert(c *gin.Context) {
	var user = model.Student{Sn: "10019", Name: "aaa", Email: "[email protected]", ClassId: 1, MonitorId: 1}
	tx := model.DB.Create(&user)
	fmt.Println(tx.Error)
	if tx.Error != nil {
		c.JSON(http.StatusOK, gin.H{
			"insert":  "error",
			"message": tx.Error,
		})
	} else {
		c.JSON(http.StatusOK, gin.H{
			"insert": "success",
		})
	}
}

func (student StudentController) Update(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	// 修改方式1
	//var user = model.Student{Id: id}
	//model.DB.Find(&user)
	//user.Name = "5A+"
	//tx := model.DB.Save(&user)
	//if tx.Error != nil {
	//	c.JSON(http.StatusOK, gin.H{
	//		"update":  "error",
	//		"message": tx.Error,
	//	})
	//} else {
	//	c.JSON(http.StatusOK, gin.H{
	//		"update": "success",
	//	})
	//}
	// 修改方式2
	tx := model.DB.Model(&model.Student{}).Where("id=?", id).Update("name", "gorm")
	if tx.Error != nil {
		c.JSON(http.StatusOK, gin.H{
			"update":  "error",
			"message": tx.Error,
		})
	} else {
		c.JSON(http.StatusOK, gin.H{
			"update": "success",
		})
	}
}

func (student StudentController) Delete(c *gin.Context) {
	id, _ := strconv.Atoi(c.Param("id"))
	var user = model.Student{Id: id}
	tx := model.DB.Delete(&user)
	if tx.Error != nil {
		c.JSON(http.StatusOK, gin.H{
			"delete":  "error",
			"message": tx.Error,
		})
	} else {
		c.JSON(http.StatusOK, gin.H{
			"delete": "success",
		})
	}
}

2.4、router

package router

import (
    "ginstudy/controller"
    "github.com/gin-gonic/gin"
)

func StudentRouter(r *gin.Engine) {
    group := r.Group("/student")
    studentController := controller.StudentController{}
    {
       group.GET("/", studentController.Select)

       group.POST("/insert", studentController.Insert)

       group.PUT("/update/:id", studentController.Update)

       group.DELETE("/delete/:id", studentController.Delete)
    }
}

3、查询

3.1、字段别名

type Student struct {
	Id        int    `json:"id"`
	Sn        string `json:"sn"`
	Name      string `json:"name"`
	Email     string `json:"email"`
	ClassId   int    `json:"class-id"`
	MonitorId int    `json:"monitor-id"`
}

3.2、条件查询

func (student StudentController) Select(c *gin.Context) {
	var users []model.Student
	// 全量查询
	//model.DB.Find(&users)
	// 条件查询1
	//model.DB.Where("id<6").Find(&users)
	//model.DB.Where("id
	// 条件查询2
	//model.DB.Where("id>1 and id<5").Find(&users)
	//model.DB.Where("id>? and id<=?", 1, 5).Find(&users)
	// 条件查询3
	//model.DB.Where("id in (?)", []int{1, 5}).Find(&users)
	// 条件查询4
	//model.DB.Where("name like ?", "%zhou%").Find(&users)
	// 条件查询5
	//model.DB.Where("id between ? and ?", 1, 3).Find(&users)
	// 条件查询6
	//model.DB.Where("id = ? or id = ?", 1, 3).Find(&users)
	model.DB.Where("id = ? or id = ?", 1, 3).Or("id = ?", 5).Find(&users)
	c.JSON(http.StatusOK, users)
}

3.3、指定字段

其他字段置空，可自定义结构体（注意指定表名）

func (student StudentController) Select(c *gin.Context) {
    var users []model.Student
    // 全量查询
    model.DB.Select("id,name").Find(&users)
    c.JSON(http.StatusOK, users)
}

3.4、排序

func (student StudentController) Select(c *gin.Context) {
    var users []model.Student
    // 全量查询
    model.DB.Order("id desc").Find(&users)
    c.JSON(http.StatusOK, users)
}

3.5、分页查询

func (student StudentController) Select(c *gin.Context) {
    var users []model.Student
    // 全量查询
    model.DB.Order("id desc").Offset(3).Limit(2).Find(&users)
    c.JSON(http.StatusOK, users)
}

3.6、计数

func (student StudentController) Select(c *gin.Context) {
    var users []model.Student
    // 全量查询
    var count int64
    model.DB.Find(&users).Count(&count)
    fmt.Println(count)
    c.JSON(http.StatusOK, users)
}

4、原生SQL

4.1、原生插入

func (student StudentController) Exec(c *gin.Context) {
    model.DB.Exec("INSERT INTO student (sn, name, email, class_id, monitor_id) VALUES ('10020', 'ceshi', '[email protected]', 1, 2)")
    c.JSON(http.StatusOK, gin.H{
       "status": "success",
    })
}

4.2、原生修改

func (student StudentController) Exec(c *gin.Context) {
	model.DB.Exec("update student set name=?  where sn=?", "gorm", 10019)
	c.JSON(http.StatusOK, gin.H{
		"status": "success",
	})
}

4.3、原生删除

func (student StudentController) Exec(c *gin.Context) {
	model.DB.Exec("delete from student where sn=?", 10019)
	c.JSON(http.StatusOK, gin.H{
		"status": "success",
	})
}

4.3、原生查询

func (student StudentController) Exec(c *gin.Context) {
    var users []model.Student
    model.DB.Raw("select * from student").Scan(&users)
    c.JSON(http.StatusOK, gin.H{
       "status": "success",
       "data":   users,
    })
}