Question

我正在使用RealmSwift，我想为我的一个对象添加一个新的主键。

我已将Realm对象更新为此

class Trip: Object {
  dynamic var id = ""
  dynamic var start = ""
  dynamic var startAddress = ""
  dynamic var end = ""
  dynamic var endAddress = ""
  dynamic var purpose = ""
  dynamic var distance = 0.0
  dynamic var tripDate = NSDate()
  dynamic var month = 0
  dynamic var year = 0
  dynamic var isWalking = false
  dynamic var isReturn = false

func primaryKey() -> String {
    return id
}

}

现在我想迁移到新版本并插入UUID String作为任何现有记录的主键。

迁移的工作原理是新的＆＃39; id＆＃39;字段已创建，但UUID字符串不写入记录。控制台上没有显示错误。

这是我添加到AppDelegate应用程序中的内容（application：didFinishLaunchingWithOptions：）

我必须遗漏一些内容，但我无法从Realm网站上的文档或示例中确定内容。

        let config = Realm.Configuration(
        // Set the new schema version. This must be greater than the previously used
        // version (if you've never set a schema version before, the version is 0).
        schemaVersion: 1,

        // Set the block which will be called automatically when opening a Realm with
        // a schema version lower than the one set above
        migrationBlock: { migration, oldSchemaVersion in
            // We haven’t migrated anything yet, so oldSchemaVersion == 0
            if (oldSchemaVersion < 1) {
                // Nothing to do!
                // Realm will automatically detect new properties and removed properties
                // And will update the schema on disk automatically
            }
    })

    // Tell Realm to use this new configuration object for the default Realm
    Realm.Configuration.defaultConfiguration = config

    // Now that we've told Realm how to handle the schema change, opening the file
    // will automatically perform the migration
    let realm = try! Realm()

    Realm.Configuration.defaultConfiguration = Realm.Configuration(
        schemaVersion: 1,
        migrationBlock: { migration, oldSchemaVersion in
            if (oldSchemaVersion < 1) {
                // The enumerate(_:_:) method iterates
                // over every Trip object stored in the Realm file
                migration.enumerate(Trip.className()) { oldObject, newObject in
                    let id = NSUUID().UUIDString
                    newObject!["id"] = id
                }
            }
    })

Answer 1

您已经提供的代码会在您已经打开Realm后设置迁移块的默认配置。您需要在打开默认Realm之前设置默认配置，以便使用迁移块。

Realm Swift Migration添加主键 - 不写入数据

1 个答案: