fix: on confilct with default value

[black-06]

• Do only one thing
• Non breaking API changes
• Tested

What did this pull request do?

close #6418 ,
and it has a little relationship with #6129

User Case Description

[jinzhu]

Hi @black-06

Which might cause a column's value overwritten by an empty value, here is an example:

type User struct {
   Name string
  UUID   string `gorm:"default:gen_random_uuid()"`
}

db.Save(&[]User{{Name: "name"}}

[black-06]

Hi @black-06

Which might cause a column's value overwritten by an empty value, here is an example:

type User struct {
   Name string
  UUID   string `gorm:"default:gen_random_uuid()"`
}

db.Save(&[]User{{Name: "name"}}

OK, I will fix it

[black-06]

Hi @black-06

Which might cause a column's value overwritten by an empty value, here is an example:

type User struct {
   Name string
  UUID   string `gorm:"default:gen_random_uuid()"`
}

db.Save(&[]User{{Name: "name"}}

Uh, the same case at playground failed, see go-gorm/playground#629.
This bug may not be caused by this mr.
If they are not related, I will fix it in the new mr

[black-06]

Hi @black-06

Which might cause a column's value overwritten by an empty value, here is an example:

type User struct {
   Name string
  UUID   string `gorm:"default:gen_random_uuid()"`
}

db.Save(&[]User{{Name: "name"}}

Sorry, I may not understand what you mean.
I wrote a test and it seems to work fine.

func TestSaveWithDefaultValue(t *testing.T) {
	if DB.Dialector.Name() != "postgres" {
		t.Skip()
	}

	type WithDefaultValue struct {
		Name string `gorm:"primaryKey"`
		UUID string `gorm:"default:gen_random_uuid()"`
	}

	err := DB.Migrator().DropTable(&WithDefaultValue{})
	AssertEqual(t, err, nil)
	err = DB.AutoMigrate(&WithDefaultValue{})
	AssertEqual(t, err, nil)

	// INSERT INTO "with_default_values" ("name") VALUES ('jinzhu') ON CONFLICT ("name") DO NOTHING RETURNING "uuid"
	err = DB.Debug().Save(&[]WithDefaultValue{{Name: "jinzhu"}}).Error
	AssertEqual(t, err, nil)

	err = DB.Debug().Save(&[]WithDefaultValue{{Name: "jinzhu"}}).Error
	AssertEqual(t, err, nil)
}

@a631807682 Would you mind helping me? 😄

[a631807682]

Hi @black-06
Which might cause a column's value overwritten by an empty value, here is an example:

type User struct {
   Name string
  UUID   string `gorm:"default:gen_random_uuid()"`
}

db.Save(&[]User{{Name: "name"}}

Sorry, I may not understand what you mean. I wrote a test and it seems to work fine.

func TestSaveWithDefaultValue(t *testing.T) {
	if DB.Dialector.Name() != "postgres" {
		t.Skip()
	}

	type WithDefaultValue struct {
		Name string `gorm:"primaryKey"`
		UUID string `gorm:"default:gen_random_uuid()"`
	}

	err := DB.Migrator().DropTable(&WithDefaultValue{})
	AssertEqual(t, err, nil)
	err = DB.AutoMigrate(&WithDefaultValue{})
	AssertEqual(t, err, nil)

	// INSERT INTO "with_default_values" ("name") VALUES ('jinzhu') ON CONFLICT ("name") DO NOTHING RETURNING "uuid"
	err = DB.Debug().Save(&[]WithDefaultValue{{Name: "jinzhu"}}).Error
	AssertEqual(t, err, nil)

	err = DB.Debug().Save(&[]WithDefaultValue{{Name: "jinzhu"}}).Error
	AssertEqual(t, err, nil)
}

@a631807682 Would you mind helping me? 😄

I'll check it tomorrow

[a631807682]

values.Columns is already filtered data, it must not contain default value, or contain default value and set a value for it at the same time.

The problem here is that if the default value is a database built-in function ( just like gen_random_uuid() or now(), we don't parse DefaultValueInterface), we don't override it. But for custom types, we do not provide a way to override DefaultValueInterface, so it is always excluded.

Here is a smaller example

	type WithDefaultValue struct {
		Name    string            `gorm:"primaryKey"`
		Content datatypes.JSONMap `gorm:"default:'{}'"`
	}

	err := DB.Migrator().DropTable(&WithDefaultValue{})
	AssertEqual(t, err, nil)
	err = DB.AutoMigrate(&WithDefaultValue{})
	AssertEqual(t, err, nil)

	dfv := WithDefaultValue{Name: "jinzhu"}
	err = DB.Save(&dfv).Error
	AssertEqual(t, err, nil)

	dfv.Content["name"] = "jinzhu"
	err = DB.Clauses(clause.OnConflict{UpdateAll: true}).Create(&dfv).Error
	AssertEqual(t, err, nil)

	var result WithDefaultValue
	err = DB.First(&result).Error
	AssertEqual(t, err, nil)
	AssertEqual(t, result.Content["name"], "jinzhu")

[black-06]

values.Columns is already filtered data, it must not contain default value, or contain default value and set a value for it at the same time.

The problem here is that if the default value is a database built-in function ( just like gen_random_uuid() or now(), we don't parse DefaultValueInterface), we don't override it. But for custom types, we do not provide a way to override DefaultValueInterface, so it is always excluded.

Here is a smaller example

	type WithDefaultValue struct {
		Name    string            `gorm:"primaryKey"`
		Content datatypes.JSONMap `gorm:"default:'{}'"`
	}

	err := DB.Migrator().DropTable(&WithDefaultValue{})
	AssertEqual(t, err, nil)
	err = DB.AutoMigrate(&WithDefaultValue{})
	AssertEqual(t, err, nil)

	dfv := WithDefaultValue{Name: "jinzhu"}
	err = DB.Save(&dfv).Error
	AssertEqual(t, err, nil)

	dfv.Content["name"] = "jinzhu"
	err = DB.Clauses(clause.OnConflict{UpdateAll: true}).Create(&dfv).Error
	AssertEqual(t, err, nil)

	var result WithDefaultValue
	err = DB.First(&result).Error
	AssertEqual(t, err, nil)
	AssertEqual(t, result.Content["name"], "jinzhu")

I'm still thinking about your comment, but your test didn't fail...

name	content
jinzhu	{"name": "jinzhu"}

[a631807682]

values.Columns is already filtered data, it must not contain default value, or contain default value and set a value for it at the same time.
The problem here is that if the default value is a database built-in function ( just like gen_random_uuid() or now(), we don't parse DefaultValueInterface), we don't override it. But for custom types, we do not provide a way to override DefaultValueInterface, so it is always excluded.
Here is a smaller example

	type WithDefaultValue struct {
		Name    string            `gorm:"primaryKey"`
		Content datatypes.JSONMap `gorm:"default:'{}'"`
	}

	err := DB.Migrator().DropTable(&WithDefaultValue{})
	AssertEqual(t, err, nil)
	err = DB.AutoMigrate(&WithDefaultValue{})
	AssertEqual(t, err, nil)

	dfv := WithDefaultValue{Name: "jinzhu"}
	err = DB.Save(&dfv).Error
	AssertEqual(t, err, nil)

	dfv.Content["name"] = "jinzhu"
	err = DB.Clauses(clause.OnConflict{UpdateAll: true}).Create(&dfv).Error
	AssertEqual(t, err, nil)

	var result WithDefaultValue
	err = DB.First(&result).Error
	AssertEqual(t, err, nil)
	AssertEqual(t, result.Content["name"], "jinzhu")

I'm still thinking about your comment, but your test didn't fail...

name content
jinzhu {"name": "jinzhu"}

Sorry, this test is to illustrate the problem with custom types before.
You can use default:gen_random_uuid(), you will find that it keeps updating the UUID.

[black-06]

You can use default:gen_random_uuid(), you will find that it keeps updating the UUID.

It didn't... Still this test, It was saved twice, but the uuid did not change.

func TestSaveWithDefaultValue(t *testing.T) {
	if DB.Dialector.Name() != "postgres" {
		t.Skip()
	}

	type WithDefaultValue struct {
		Name string `gorm:"primaryKey"`
		UUID string `gorm:"default:gen_random_uuid()"`
	}

	err := DB.Migrator().DropTable(&WithDefaultValue{})
	AssertEqual(t, err, nil)
	err = DB.AutoMigrate(&WithDefaultValue{})
	AssertEqual(t, err, nil)

	// INSERT INTO "with_default_values" ("name") VALUES ('jinzhu') ON CONFLICT ("name") DO NOTHING RETURNING "uuid"
	err = DB.Debug().Save(&[]WithDefaultValue{{Name: "jinzhu"}}).Error
	AssertEqual(t, err, nil)

	err = DB.Debug().Save(&[]WithDefaultValue{{Name: "jinzhu"}}).Error
	AssertEqual(t, err, nil)
}

[a631807682]

As #6434 (review) says, if the value is not set, it will not be overridden, whereas if the value is set it should be.

Hi @black-06

Which might cause a column's value overwritten by an empty value, here is an example:

type User struct {
   Name string
  UUID   string `gorm:"default:gen_random_uuid()"`
}

db.Save(&[]User{{Name: "name"}}

Does not rewrite to empty value, I tried other cases, and there is no difference from the current behavior (including the default value for built-in functions, such as gen_random_uuid() or now(), which usually do not need to set the value, but set the value will be overwritten, but this can only depend on how the user uses it).

cc @jinzhu