RLMArray 到 RLMLinkingObjects 迁移

Question

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

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.

因此，我向 + (NSArray *)requiredProperties 添加了可选项，但不清楚如何处理 SFCHChat.messages 和 SFCHMessage.chat。这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"],
+             };
+}
+

总而言之，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 SFCHMessage 添加了一个 chat 属性，并用 RLMLinkingObjects.

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。我的案例真的需要迁移块吗？我将如何执行此迁移？

Answer 1

是的，我认为您可以修改 Realm 的架构并运行迁移。

当 Realm 将可选值添加到所有属性时，您可以通过简单地显式将其明确设为必需来缓解这些问题，但在添加或删除属性时，只需要迁移即可。

除非属性中的数据会在迁移中丢失，除非您选择保留它们，运行进行 Realm 迁移就像简单地添加一个空块一样简单。

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，迁移将运行并且您的文件将被升级。

RLMArray 到 RLMLinkingObjects 迁移

RLMArray to RLMLinkingObjects migration

objective-c

realm

ios

realm-migration