Gorm function Updates do not seem to behave well

(ENGLISH version)

Why `gorm.DB.Updates` always changes the `created_at` field when performing updating?

Here is a minimalist example:

package main

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

var Db *gorm.DB

type VModel struct {
    ID        uint64 `gorm:"index:id; primarykey, autoIncrement"`
    CreatedAt time.Time
    UpdatedAt time.Time
    DeletedAt gorm.DeletedAt
}

type Archive struct {
    VModel
    Path     string `gorm:"index:path;type:varchar(100)"`
    Password string `gorm:"type:varchar(10)"`
}

func (m *Archive) Exist() (*Archive, bool) {
    var existed Archive
    err := Db.Model(m).Where("path = ?", m.Path).Find(&existed).Error
    if err == nil && existed.Path == m.Path {
        return &existed, true
    }
    return &existed, false
}

func (m *Archive) Update(attr *Archive) error {
    updateInfo := make(map[string]interface{}, 0)
    updateInfo["path"] = attr.Path
    updateInfo["password"] = attr.Password
    //return Db.Model(m).Select("*").Omit("created_at").Updates(updateInfo).Error
    return Db.Model(m).Updates(updateInfo).Error
    //return Db.Model(m).Select("path", "password").Updates(updateInfo).Error
}

func (m *Archive) Create() error {
    return Db.Create(m).Error
}

func main() {
    dsn := "${your-connection-string}"
    Db, _ = gorm.Open(mysql.Open(dsn), &gorm.Config{})

    for i := 0; i < 3; i++ {
        a := &Archive{
            Path:     "/home/admin",
            Password: "12345",
        }
        exist, ok := a.Exist()
        if ok {
            err := exist.Update(a)
            if err != nil {
                log.Fatalf("Update failed %s", err.Error())
            }
        } else {
            err := a.Create()
            if err != nil {
                log.Fatalf("Create failed %s", err.Error())
            }
        }

        fmt.Println("### ", i, " ### ", a.CreatedAt)
    }
}

And here is the output:

###  0  ###  2023-03-13 23:15:14.232 +0800 CST
###  1  ###  0001-01-01 00:00:00 +0000 UTC
###  2  ###  0001-01-01 00:00:00 +0000 UTC

Although field created_at in database is not changed to 0001-01-01 00:00:00 +0000 UTC, the struct in the memory is obviously modified. And I find this behavior very annoying because in my situation, I wish to get some data from frontend, save them to database, and then return them to the frontend(Actually I will modify part of the data before returning them). But now every Updates operation changes the created_at field to 0001-01-01 00:00:00 +0000 UTC so it becomes a total mess at the frontend.

According to doc, I tried Db.Model(m).Select("*").Omit("created_at").Updates(updateInfo) and Db.Model(m).Select("path", "password").Updates(updateInfo), but neither works.

Of course, I can read data from database after each update, but it costs me one more interaction with database and might drag my service down when data accumulate to a huge number.

So is there a graceful way to bypass that? Or could you fix that in future releases? Thank you.

(中文版)

我看到社区既有英文提问又有中文提问所以为了方便作者解答又写了一下中文版问题

现在发现 gorm.DB.Updates 这个方法在更新数据库的时候会把 created_at 设置为 0001-01-01 00:00:00 +0000 UTC，复现过程以及输出参考上面的代码

我目前的场景是从前端接收数据，然后更新到数据库中，同时做一些计算后再将这个数据返回给前端；其中计算会用到 created_at 字段，最终的计算结果也会返回给前端展示，现在 gorm.DB.Updates 函数的奇怪行为导致前端展示的数据都是错的；当然我可以每次调用完 gorm.DB.Updates 函数接着再从数据库中读一次数据，但是这样就增加了一次和数据库的交互，对性能会有影响

另外我参考官方文档尝试了 Db.Model(m).Select("*").Omit("created_at").Updates(updateInfo) 和 Db.Model(m).Select("path", "password").Updates(updateInfo)，然而都没有用，它们都会在 update 时修改内存中的结构体的 created_at 字段，把它改成 0001-01-01 00:00:00 +0000 UTC

不知道有没有更好的方法规避掉 gorm.DB.Updates 对 created_at 的修改？或者你们可以修改一下 gorm.DB.Updates 的行为吗？谢谢