Save is trying to update created_at column

Question

We are updating our project from v1 to v2. When we try to update a row by providing only changed fields as a struct, it tries to set created_at column and returns an error. This was working back in v1. According to documentation, during update operations, fields with default values are ignored.

err := r.writeDB.Save(&Record{
    Model:   Model{
        ID:        1,
    },
    Name:    "AB",
}).Error

if err != nil {
    return err
}

Generates the following SQL statement

[3.171ms] [rows:0] UPDATE `records` SET `created_at`='0000-00-00 00:00:00',`updated_at`='2020-11-12 15:38:36.285',`name`='AB' WHERE `id` = 1

Returns following error

Error 1292: Incorrect datetime value: '0000-00-00' for column 'created_at' at row 1

With these entities

type Model struct {
    ID        int       `gorm:"primary_key,type:INT;not null;AUTO_INCREMENT"`
    CreatedAt time.Time `gorm:"type:TIMESTAMP(6)"`
    UpdatedAt time.Time `gorm:"type:TIMESTAMP(6)"`
}

type Record struct {
    Model
    Name         string
    Details      string
}

There is DB.Omit which allows ignoring a column when executing an update query. But this requires a lot of refactoring in the codebase. Does the behavior changed or is there something missing?

Answer 1

This might help you. Change the structure field (or add to replace default gorm.Model field) like this:

CreatedAt time.Time `gorm:"<-:create"` // allow read and create, but don't update

This tag helps to save created data from update.

Answer 2

I was able to work around this problem using Omit() before save. Like this:

result := r.db.Omit("created_at").Save(item)

It omits the CreatedAt from the resulting update query, and updates everything else.