与非标准化数据域迁移

Question

比方说，你有一个像

class Person: Object { 
    var dynamic firstName: String = "" 
    var dynamic lastName: String = "" 
} 

境界对象现在，我想升级数据库，并提取出姓氏进入一个新的类像这样

class LastName: Object { 
    var dynamic sirName: String = "" 

    override public class func primaryKey() -> String { 
     return "sirName" 
    } 
} 

class Person: Object { 
    var dynamic firstName: String = "" 
    var dynamic lastName: LastName! 
} 

什么迁移看起来像什么？我尝试了一个简单的迁移，但这可能会导致具有相同primaryKey的多个LastName对象。

Answer 1

在你AppDelegate的didFinishLaunchingWithOptions：

let configuration = Realm.Configuration(
    schemaVersion: 1, //This must be larger than the previous schemaVersion 
    migrationBlock: { migration, oldSchemaVersion in 
     if oldSchemaVersion < 1 { 
      migration.enumerate(Person.className()) { oldObject, newObject in 
       let lastName = oldObject!["lastName"] as! String 
       let newValue: [String: String] = ["sirName": lastName] 
       let createdObject = migration.create(LastName.className(), value: newValue) 
       newObject!["lastName"] = createdObject 
      } 
     } 
}) 

Realm.Configuration.defaultConfiguration = configuration // Set the new configuration as default 

let realm = try! Realm() // Open the default realm to perform the migration 

要添加，这现在有primaryKey作品以及与模型看起来像这样：

class Person: Object { 
    dynamic var firstName: String = "" 
    dynamic var lastName: LastName! 
} 

class LastName: Object { 
    dynamic var sirName: String = "" 

    override static func primaryKey() -> String? { 
     return "sirName" 
    } 
} 

但这种迁移将无法正常工作如果由于primaryKey是每个对象的唯一标识符而存在lastName的重复项，则要么确保不会有重复项，请使用另一个属性作为primaryKey或在LastName对象中完全不使用primaryKey。