删除Realm对象中的属性

Question

我正在尝试删除我的一个Realm对象中的属性,但是我不确定如何为此编写迁移.

我刚刚从我的对象的头文件中删除了该属性,但是这不起作用,因为我收到此错误:

由于未捕获的异常'RLMException'而终止应用程序,原因:'由于以下错误,对象类型'Stock'需要迁移: - 最新对象模型中缺少属性'percentageOn'.

我知道如何编写迁移添加字段,但如何删除一个？

Answer 1

大卫说的是对的.如果确保正确执行迁移,则Realm可以轻松处理已删除和添加的属性.除非您确实仍需要值,否则您percentageOn甚至可以将迁移块留空,就像Realm网站上的示例一样:

// Inside your [AppDelegate didFinishLaunchingWithOptions:]

// Notice setSchemaVersion is set to 1, this is always set manually. It must be
// higher than the previous version (oldSchemaVersion) or an RLMException is thrown
[RLMRealm setSchemaVersion:1
            forRealmAtPath:[RLMRealm defaultRealmPath] 
        withMigrationBlock:^(RLMMigration *migration, NSUInteger oldSchemaVersion) {
  // 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
  }
}];

// now that we have called `setSchemaVersion:withMigrationBlock:`, opening an outdated
// Realm will automatically perform the migration and opening the Realm will succeed
[RLMRealm defaultRealm];