Swift中的领域迁移

我有一个领域对象建模为这样

class WorkoutSet: Object {
     // Schema 0
     dynamic var exerciseName: String = ""
     dynamic var reps: Int = 0
     // Schema 0 + 1
     dynamic var setCount: Int = 0
}

我正在尝试执行迁移

在我的

AppDelegate

中，我导入了

RealmSwift

在函数中，

didfishlaunchwithoptions

I调用

Migrations().checkSchema()

迁移是在另一个文件中声明的类

在该文件中有一个声明为的结构

func checkSchema() {
    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
            switch oldSchemaVersion {
            case 1:
                break
            default:
                // Nothing to do!
                // Realm will automatically detect new properties and removed properties
                // And will update the schema on disk automatically
                self.zeroToOne(migration)
            }
    })
}

func zeroToOne(migration: Migration) {
    migration.enumerate(WorkoutSet.className()) {
        oldObject, newObject in
        let setCount = 1
        newObject!["setCount"] = setCount
    }
}

---

将

setCount

添加到模型中时出现错误

您需要调用迁移。仅仅创建一个配置，不会调用它。有两种方法可以做到这一点：

将迁移设置为领域的默认配置-

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

    if oldSchemaVersion < 1 {
      migration.enumerate(WorkoutSet.className()) { oldObject, newObject in
        newObject?["setCount"] = setCount
      }    
    }
  }
) 
Realm.Configuration.defaultConfiguration = config   

let config=Realm.Configuration(
//设置新架构版本。该版本必须大于以前使用的版本
//版本（如果以前从未设置过架构版本，则版本为0）。
阴谋厌恶：1，
//设置使用打开域时自动调用的块
//低于上面设置的架构版本
migrationBlock:{migration，oldSchemaVersion in
如果oldschemaversation<1{
migration.enumerate（WorkoutSet.className（））{oldObject，newObject在
新建对象？[“设置计数”]=设置计数
}    
}
}
) 
Realm.Configuration.defaultConfiguration=config

或

使用migrateRealm手动迁移：

migrateRealm（配置）

---

现在，您的迁移应该可以正常工作了

因为您刚刚创建了

领域配置

。如果需要，领域将调用迁移块。您不能直接调用迁移

所以，要调用迁移块，您应该将配置对象设置为Realm，或者设置为默认配置。然后创建领域实例

因此，您需要执行以下操作：

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
        switch oldSchemaVersion {
        case 1:
            break
        default:
            // Nothing to do!
            // Realm will automatically detect new properties and removed properties
            // And will update the schema on disk automatically
            self.zeroToOne(migration)
        }
})

let realm = try! Realm(configuration: config) // Invoke migration block if needed

---

你有什么错误？您可以共享吗？属性“setCount”已添加到最新模型别忘了调用import realmswift不要调用

let realm=try！领域（配置：config）

强制。它被标记为抛出是有原因的（例如，设备上没有空间执行迁移）。相反，您应该在do catch块中调用它。是否有一种方法可以自动执行此操作？我认为这是相当直接的，如果值可以是零。。。有什么想法吗？