AlterColumn(dst interface{}, field string) error
	MigrateColumn(dst interface{}, field *schema.Field, columnType ColumnType) error
	// MigrateColumnUnique migrate column's UNIQUE constraint, it's part of MigrateColumn.
	MigrateColumnUnique(dst interface{}, field *schema.Field, columnType ColumnType) error
	HasColumn(dst interface{}, field string) bool
	RenameColumn(dst interface{}, oldName, field string) error

		if err := m.DB.Migrator().AlterColumn(value, field.DBName); err != nil {
			return err
		}
	}

	if err := m.DB.Migrator().MigrateColumnUnique(value, field, columnType); err != nil {
		return err
	}

	return nil
}

func (m Migrator) MigrateColumnUnique(value interface{}, field *schema.Field, columnType gorm.ColumnType) error {
	unique, ok := columnType.Unique()
	if !ok || field.PrimaryKey {

	// It causes field unnecessarily migration.
	// Therefore, we need to record the UniqueIndex on this column (exclude Mul UniqueIndex) for MigrateColumnUnique.
	UniqueIndex string
}

func (field *Field) BindName() string {
	return strings.Join(field.BindNames, ".")
}

// ParseField parses reflect.StructField to Field