*string and *int cause left join not to return nil

[Axb12]

This is my example address:
https://github.com/Axb12/playground.git

Description

I have two model structs. When I combine these two structs for querying, a problem occurs.

type User struct {
	ID   uuid.UUID `gorm:"primarykey;column:id"`
	Name string    `gorm:"column:name"`
}

func (User) TableName() string {
	return "users"
}

type Order struct {
	ID     uuid.UUID `gorm:"primarykey;column:id"`
	UserID uuid.UUID `gorm:"column:user_id"`
	Name   string    `gorm:"column:name"`
}

func (Order) TableName() string {
	return "orders"
}

It is correct when I use the following query. When the order is not matched, nil is returned. Like this user: {31e8f5fe-9848-4088-b786-ff75f1ab7563 user 1} order: <nil>

user, order := &User{}, &Order{}
userTable, orderTable := user.TableName(), order.TableName()

var uo []struct {
	User
	*Order
}
err = db.Model(user).Select(
	userTable+".*, "+orderTable+".*",
).Joins(
	"LEFT JOIN "+orderTable+" ON "+userTable+".id = "+orderTable+".user_id",
).Where(userTable+".id = ?", "31e8f5fe-9848-4088-b786-ff75f1ab7563").Scan(&uo)

But when I use the following order struct. When the order is not matched, nil is not returned. Like this user: {31e8f5fe-9848-4088-b786-ff75f1ab7563 user 1} order: &{00000000-0000-0000-0000-000000000000 00000000-0000-0000-0000-000000000000 <nil>}

type Order struct {
	ID     uuid.UUID `gorm:"primarykey;column:id"`
	UserID uuid.UUID `gorm:"column:user_id"`
	Name   *string   `gorm:"column:name"`
}

But *uuid.UUID will still return nil. If it is *string or *int etc., it will not return nil.

Expected answer

I want to know why this is happening. It makes my logic for judging whether the order matches inconsistent.

I tried to modify it in field.go like this, and it worked in my case. I don't know what this will affect.

	fallbackSetter := func(ctx context.Context, value reflect.Value, v interface{}, setter func(context.Context, reflect.Value, interface{}) error) (err error) {
		if v == nil {
			field.ReflectValueOf(ctx, value).Set(reflect.New(field.FieldType).Elem())
		} else {
			reflectV := reflect.ValueOf(v)
			if reflectV.Elem().Kind() == reflect.Ptr && reflectV.Elem().IsNil() {
				return
			}

[github-actions]

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