Swift 中的领域迁移

素材狗 2022-01-01 10:06:11 文章分类：移动开发问题点击数：次

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Realm migrations in Swift(Swift 中的领域迁移)

本文介绍了Swift 中的领域迁移的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我有一个如此建模的领域对象

类 WorkoutSet: Object {//架构 0动态变量练习名称:字符串 = ""动态 var reps: Int = 0//架构 0 + 1动态变量 setCount: Int = 0}

我正在尝试执行迁移.

在我的 AppDelegate 中，我已经导入了 RealmSwift.

在函数 didFinishLaunchWithOptions 我调用

Migrations().checkSchema()

Migrations 是在另一个文件中声明的类.

在该文件中有一个这样声明的结构.

func checkSchema() {领域.配置(//设置新的架构版本.这必须大于以前使用的//版本(如果您之前从未设置过架构版本，则版本为 0).架构版本:1，//设置打开 Realm 时自动调用的块//架构版本低于上面的集合迁移块:{迁移，oldSchemaVersion in//我们还没有迁移任何东西，所以 oldSchemaVersion == 0切换 oldSchemaVersion {情况1:休息默认://没事做！//Realm 会自动检测新属性和移除的属性//并且会自动更新磁盘上的模式self.zeroToOne(迁移)}})}func zeroToOne(迁移:迁移){migration.enumerate(WorkoutSet.className()) {旧对象，新对象让 setCount = 1newObject!["setCount"] = setCount}}

将 setCount 添加到模型时出现错误

解决方案

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:

将您的配置与迁移设置为 Realm 的默认配置-

让 config = Realm.Configuration(//设置新的架构版本.这必须大于以前使用的//版本(如果您之前从未设置过架构版本，则版本为 0).架构版本:1，//设置打开 Realm 时自动调用的块//架构版本低于上面的集合迁移块:{迁移，oldSchemaVersion in如果 oldSchemaVersion <1 {migration.enumerate(WorkoutSet.className()) { oldObject, newObject innewObject?["setCount"] = setCount}}})Realm.Configuration.defaultConfiguration = 配置

或

使用 migrateRealm 手动迁移:

<块引用>

migrateRealm(配置)

现在您的迁移应该可以正常工作了.

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
}

I am trying to perform a migration.

Within my AppDelegate I have imported RealmSwift.

Within the function didFinishLaunchWithOptions I call

Migrations().checkSchema()

Migrations is a class declared in another file.

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
    }
}

I am getting an error for adding setCount to the model

解决方案

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

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