Swift中的领域迁移 [英] Realm migrations in Swift

问题描述

我有一个建模的领域对象

I have a Realm Object modeled as so

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，我已经导入了RealmSwift.

Within my AppDelegate I have imported RealmSwift.

在函数didFinishLaunchWithOptions中，我调用

Migrations().checkSchema()

迁移是在另一个文件中声明的类.

Migrations is a class declared in another file.

在该文件中，有一个声明为这样的结构.

Within that file there is a struct declared as so.

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添加到模型时出现错误

I am getting an error for adding setCount to the model

推荐答案

您将需要调用迁移.仅创建配置，将不会调用它.有两种方法可以做到这一点:

You will need to invoke the migration. Merely creating a configuration, won't invoke it. There are two ways of doing this:

1. 通过迁移将您的配置设置为Realm的默认配置-

1. Set your configuration with migration as Realm's default configuration-

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   

OR

1. 使用migrateRealm手动迁移:

migrateRealm(config)

migrateRealm(config)

现在，您的迁移应该可以正常工作了.

Now your migration should work properly.

这篇关于Swift中的领域迁移的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！