GORM Playground Link

https://github.com/go-gorm/playground/pull/1

Description

mysql数据库，当修改一对多的外键数据时，外键对应的数据会被双倍插入数据库。代码如下：

package main

import (
    "fmt"

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

type User struct {
    ID        int     `gorm:"primaryKey"`
    Name      string  `gorm:"index"`
    PhoneList []Phone `gorm:"foreignKey:UserRefer"`
}

type Phone struct {
    UserRefer int `gorm:"index"`
    Number    string
}

func main() {
    dsn := "tempa:1920*1080@tcp(10.0.182.190:3306)/tempdb?charset=utf8mb4&parseTime=True&loc=Local"
    db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})
    if err != nil {
        fmt.Println("can not connect db %s", err.Error())
    }
    err = db.AutoMigrate(&User{}, &Phone{})
    if err != nil {
        fmt.Println("can not update db %s", err.Error())
    }
    user := &User{
        Name: "root",
    }
    result := db.Create(user)
    if result.Error == nil {
        fmt.Println("create record success ", result.RowsAffected)
    }
    user.PhoneList = []Phone{
        {Number: "111111"},
        {Number: "222222"},
        {Number: "333333"},
        {Number: "444444"},
    }
    result = db.Save(user)
    if result.Error == nil {
        fmt.Println("save record success ", result.RowsAffected)
    }
    fmt.Println(112233)
}

代码执行后phone表应该有4条数据，但是phone表有8条数据，有4条是重复数据。使用mysql数据库可以复现，sqlite数据库正常。其他数据库未测试。 phone表如下：

mysql> select * from phones;
+------------+--------+
| user_refer | number |
+------------+--------+
|          1 | 111111 |
|          1 | 222222 |
|          1 | 333333 |
|          1 | 444444 |
|          1 | 111111 |
|          1 | 222222 |
|          1 | 333333 |
|          1 | 444444 |
+------------+--------+
8 rows in set (0.00 sec)

Comment From: github-actions[bot]

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Comment From: demoManito

How to solve

    type Phone struct {
+       ID        int `gorm:"primaryKey"`
        UserRefer int `gorm:"index"`
        Number    string
    }

    user.PhoneList = []Phone{
+       {ID: 1, Number: "111111"},
+       {ID: 2, Number: "222222"},
+       {ID: 3, Number: "333333"},
+       {ID: 4, Number: "444444"},
-       {Number: "111111"},
-       {Number: "222222"},
-       {Number: "333333"},
-       {Number: "444444"},
    }

db.Save(user) the following SQL will be executed:

INSERT INTO `phones` (`user_refer`,`number`,`id`) VALUES (1,'1111112',1),(1,'222222',2),(1,'333333',3),(1,'444444',4) ON DUPLICATE KEY UPDATE `user_refer`=VALUES(`user_refer`);

UPDATE `users` SET `name`='root' WHERE `id` = 1;

Describe

phones missing primary key or unique index.

you can refer to mysql ON DUPLICATE KEY UPDATE (https://dev.mysql.com/doc/refman/8.0/en/insert-on-duplicate.html).

Comment From: github-actions[bot]

This issue has been automatically marked as stale because it has been open 360 days with no activity. Remove stale label or comment or this will be closed in 180 days