Gorm Empty primary key being inserted

GORM Playground Link

https://github.com/go-gorm/playground/pull/587

Description

From what I understand about gorm, struct fields that are equal to their zero values should be automatically omitted when inserting into a database. Specifically, if the primary key of a struct is equal to its zero value, gorm should not attempt to insert that value. This was the case prior to v1.20.4, which contains this commit, breaking the described functionality.

For example...

import "github.com/google/uuid"

type Person struct {
   ID               uuid.UUID
   FirstName string
   LastName string
}

function CreatePerson(db *gorm.DB) (Person, error) {
  person := {
     FirstName: "John",
     LastName: "Doe",
   }

   tx := db.Debug().Create(&person) 
   // EXPECTED debug output: INSERT INTO "persons" ("first_name", "last_name") VALUES ('John', 'Doe')
   // ACTUAL debug output: INSERT INTO "persons" ("id", "first_name", "last_name") VALUES ('00000000-0000-0000-0000-000000000000', 'John', 'Doe')

   return person, tx.Error
}

Comment From: TheDhejavu

Hey @chad-bekmezian-snap

try this:

import "github.com/google/uuid"

type Person struct {
   ID               uuid.UUID
   FirstName string
   LastName string
}

func (p *Person) BeforeCreate(tx *gorm.DB) (err error) {
    p.ID = uuid.New()
    return 
}


func CreatePerson(db *gorm.DB) (Person, error) {
  person := {
     FirstName: "John",
     LastName: "Doe",
   }

   tx := db.Debug().Create(&person) 

   return person, tx.Error
}

Comment From: chad-bekmezian-snap

Hey @chad-bekmezian-snap

try this:

```go import "github.com/google/uuid"

type Person struct { ID uuid.UUID FirstName string LastName string }

func (p Person) BeforeCreate(tx gorm.DB) (err error) { p.ID = uuid.New() return }

func CreatePerson(db *gorm.DB) (Person, error) { person := { FirstName: "John", LastName: "Doe", }

tx := db.Debug().Create(&person)

return person, tx.Error } ```

That does of course work, however it does not change the fact that prior to v1.24.4 empty ids were not inserted, as is consistent with Gorm's behavior. Additionally, our enterprise database is generating the uuid, since Gorm omits the zeroed ID field--until now.

Comment From: a631807682

cc @jinzhu

Comment From: efournival

@jinzhu I'm facing this issue too, that looks like a regression. Would you accept a PR?

Comment From: manicar2093

Maybe adding test for this stage can be a useful way to avoid delete this code. 😃 I'm with the same issue 😢

Comment From: manicar2093

Hi! Sorry, is there any change attached to this issue? 😮

Comment From: martinmunillas

I'm facing this too :(

I've managed to find a workaround for now. If you tell gorm there is a default (which can be empty) it wont send the zero value

type Model struct {
  ID uuid.UUID `gorm:"default:"`
}

Of course this, first, looks ugly and second, makes it prone to error and forget adding it

Comment From: martinmunillas

I just opened a PR to solve this, go give it some love https://github.com/go-gorm/gorm/pull/6970

Comment From: jinzhu

https://github.com/go-gorm/gorm/pull/6970#issuecomment-2076668010