Gorm undocumented breaking change in gorm v2, the value of the ignored field gorm:"-" in struct is not updated when use Update().

GORM Playground Link

https://github.com/go-gorm/playground/pull/480

Description

In gorm V1 , the value of the ignored field gorm:"-" will changed after update. In gorm V2 now , the value will not changed. Is this behavior change a bug ? If not , is there a writing style to get results like V1 ? Thanks so much !

Comment From: a631807682

https://gorm.io/docs/models.html#Fields-Tags

Tag Name	Description
<-	set field’s write permission, <-:create create-only field, <-:update update-only field, <-:false no write permission, <- create and update permission

Comment From: XBreath

@a631807682 Thanks for the reply ! But it doesn't work. 'age' does not exist in table. if use '<-:false', will got same results(not updated). if use '<-create' or '<-update', the sql execution will failed. ERROR: column "age" of relation "user" does not exist (SQLSTATE 42703)

Comment From: a631807682

you should set read permission

Tag Name	Description
->	set field’s read permission, ->:false no read permission

Comment From: XBreath

@a631807682 Thanks for the reply !! I have try the read permission tags '->' and '->:false'. but it doesn't work. the value in struct is not updated.

Comment From: a631807682

    ...
    Age       uint `gorm:"->:false;<-:update"`

doesn't this work?

Comment From: XBreath

``go ... Age uintgorm:"->:false;<-:update"`

doesn't this work? ```

The value of Age in struct have changed after Update(). But the sql execution will failed. ERROR: column "age" of relation "user" does not exist (SQLSTATE 42703) [rows:0] UPDATE "user" SET "updated_at"='2022-05-30 19:10:01.058',"age"=18 WHERE "id" = 453

Comment From: a631807682

@XBreath The problem age not exists in table, you are not using AutoMigrate? you need to create this field on the database

Comment From: XBreath

yes, not using AutoMigrate() in my test. But in V1 , using gorm: "-", will not create this field in table. so age not exists in table. now v1 need to upgrade to V2.
using AutoMigrate() and gorm:"->:false;<-:update" will create this field in table. Is there a way without creating ignored field like "Age"? @a631807682

Comment From: a631807682

ignore this field, - no read/write permission, -:migration no migrate permission, -:all no read/write/migrate permission

Comment From: XBreath

use this like https://github.com/go-gorm/playground/pull/480, the value of age in struct will not update after use Update(). Is this a problem?