gin 数据库关系

一对一关系

type IDCard struct {
    gorm.Model
    StudentID uint
    Num       int
}

type Student struct {
	gorm.Model
	IDCard  IDCard
    StudentName string
}

一对多关系

type Class struct {
    gorm.Model
    ClassName string
    Students []Student
}
type Student struct {
    gorm.Model
    StudentName string
    ClassID uint
}

多对多关系

type Student struct {
	gorm.Model
	StudentName string
	Teachers    []Teacher `gorm:"many2many:student_teachers;"`
}

type Teacher struct {
    gorm.Model
    TeacherName string
    Students    []Student `gorm:"many2many:student_teachers;"`
}

定义表结构

type Class struct {
	gorm.Model
	ClassName string
	Students  []Student
}

type Student struct {
	gorm.Model
	StudentName string
	ClassID     uint
	IDCard      IDCard
	Teachers    []Teacher `gorm:"many2many:student_teachers;"`
}

type IDCard struct {
	gorm.Model
	StudentID uint
	Num       int
}

type Teacher struct {
	gorm.Model
	TeacherName string
	Students    []Student `gorm:"many2many:student_teachers;"`
}

type Page struct {
	PageNum  int    `form:"page_num"`
	PageSize int    `form:"page_size"`
	Keyword  string `form:"keyword"`
	Desc     bool   `form:"desc"`
}

type StudentResponse struct {
    StudentName string
}

跨域请求

func Cors() gin.HandlerFunc {
	return func(c *gin.Context) {
		method := c.Request.Method
		origin := c.Request.Header.Get("Origin")
		if origin != "" {
			c.Header("Access-Control-Allow-Origin", "*") // 可将将 * 替换为指定的域名
			c.Header("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, UPDATE")
			c.Header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Authorization")
			c.Header("Access-Control-Expose-Headers", "Content-Length, Access-Control-Allow-Origin, Access-Control-Allow-Headers, Cache-Control, Content-Language, Content-Type")
			c.Header("Access-Control-Allow-Credentials", "true")
		}
		if method == "OPTIONS" {
			c.AbortWithStatus(http.StatusNoContent)
		}
		c.Next()
	}
}

链接数据库 创建数据表

func main() {
	dsn := "root:alger@tcp(127.0.0.1:3306)/gosql?charset=utf8mb4&parseTime=True&loc=Local"
	db, err := gorm.Open("mysql", dsn)
	if err != nil {
		fmt.Println(err)
		panic(err)
	}
	db.AutoMigrate(&Teacher{}, &Class{}, &Student{}, &IDCard{})
    defer db.Close()
}

启动服务 使用跨域中间件

r := gin.Default()
r.Use(Cors())
//r.POST...
r.Run(":8080")

请求的增删改查

//分页查询
r.GET("/student", func(ctx *gin.Context) {
    var p Page
    if ctx.ShouldBindQuery(&p) != nil {
        ctx.JSON(http.StatusUnauthorized, gin.H{
            "err_msg": "参数错误",
        })
        return
    }
    if p.PageNum  0 {
        p.PageNum = 1
    }
    var students []Student

    if err := db.Limit(p.PageSize).Offset((p.PageNum-1)*p.PageSize).Find(&students).Error; err != nil {
        ctx.JSON(http.StatusUnauthorized, gin.H{
            "err_msg":  err.Error(),
        })
    }
    var total int
    db.Model(&Student{}).Count(&total)
    pageNum := total / p.PageSize
    if total % p.PageSize != 0{
        pageNum++
    }
    ctx.JSON(http.StatusOK, gin.H{
        "code":200,
        "msg":"查询成功",
        "data": students,
        "total": total,

    })
})

//id查询单个学生
r.GET("/student/:id", func(ctx *gin.Context) {
    var student Student
    id := ctx.Param("id")
    db.Preload("Teachers").Preload("IDCard").First(&student, id)
    ctx.JSON(http.StatusOK, student)
})

//修改学生
r.PUT("/student/:id", func(ctx *gin.Context) {
    var student Student
    id := ctx.Param("id")
    db.First(&student, id)
    ctx.BindJSON(&student)
    db.Save(&student)
    ctx.JSON(http.StatusOK, student)
})

//删除学生
r.DELETE("/student/:id", func(ctx *gin.Context) {
    var student Student
    id := ctx.Param("id")
    db.First(&student, id)
    db.Delete(&student)
    ctx.JSON(http.StatusOK, gin.H{"id #" + id: "deleted"})
})

//指定返回数据

type StudentResponse struct {
    StudentName string
}

r.GET("/student", func(ctx *gin.Context) {
    // var students []Student
    data := &[]*StudentResponse{}
    db.Table("students").Find(&data)
    ctx.JSON(http.StatusOK, data)
})