Question

我有一个包含两个对象的模型：SFCHChat和SFCHMessages，它们具有一对多的关系。

由于从Realm 0.98升级到2.0，我现在在生产中遇到以下异常：

Migration is required due to the following errors: - Property 'SFCHChat.chatId' has been made optional. - Property 'SFCHChat.lastReadedMessageId' has been made optional. - Property 'SFCHMessage.chat' has been added. - Property 'SFCHMessage.messageId' has been made optional. - Property 'SFCHMessage.chatId' has been made optional. - Property 'SFCHMessage.userId' has been made optional. - Property 'SFCHMessage.message' has been made optional. - Property 'SFCHUser.initials' has been made optional. - Property 'SFCHUser.userId' has been made optional. - Property 'SFCHChat.messages' has been removed.

所以，我已经为+ (NSArray *)requiredProperties添加了选项，但目前尚不清楚如何进行SFCHChat.messages和SFCHMessage.chat。以下是这些对象的代码差异：

### SFCHMessage.h
-@property (readonly) SFCHChat *chat;
+@property SFCHChat *chat;

### SFCHMessage.m
-- (SFCHChat *)chat
-{
-    return [[self linkingObjectsOfClass:@"SFCHChat" forProperty:@"messages"] firstObject];
-}
-

### SFCHChat.h

-@property RLMArray<SFCHMessage> *messages;
+@property (readonly) RLMLinkingObjects *messages;

### SFCHChat.m

++ (NSDictionary *)linkingObjectsProperties {
+    return @{
+             @"messages": [RLMPropertyDescriptor descriptorWithClass:SFCHMessage.class propertyName:@"chat"],
+             };
+}
+

总结一下，我将Realm对象上的数组迁移到RLMLinkingObjects属性，因为linkingObjectsOfClass已被弃用。因此，我没有将SFCHMessage个对象添加到SFCHChat.messages RLMArray，而是向每个chat添加了SFCHMessage属性，并使用RLMLinkingObjects从它们链接回来。

看起来更改为(readonly)被视为删除领域中的属性，而删除它被视为添加属性。我是否真的需要一个迁移块用于我的案例？我将如何执行此迁移？

Answer 1

是的，我说它适合您使用Realm的架构并进行迁移。

虽然Realm可以通过简单地明确地将它们添加到所有属性来缓解所有属性，但在添加或删除属性时，只需要迁移。

除非您选择保留它们，否则属性中的数据将在迁移中丢失，否则运行Realm迁移就像添加空块一样简单。

RLMRealmConfiguration *configuration = [RLMRealmConfiguration defaultConfiguration];
configuration.schemaVersion = 1; //Must be incremented by 1 each time the schema is changed.
configuration.migrationBlock = ^(RLMMigration *migration, uint64_t oldSchemaVersion) { };
[RLMRealmConfiguration setDefaultConfiguration:configuration];

这将使您下次调用[RLMRealm defaultRealm]时，将运行迁移并升级您的文件。

RLMArray到RLMLinkingObjects迁移

1 个答案: