iOS RestKit不能将本地实体保存到数据库 [英] iOS RestKit can not save local entity to database

问题描述

我使用RestKit 0.20来解析JSON数据并保存到数据库。
这是一个映射实体SchoolClass，由RestKit处理并保存。
我有另一个实体叫MyClass，它存储我选择的类。这一个只在设备上本地。

I am using RestKit 0.20 to parse JSON data and save to database. THere is a mapped entity SchoolClass, which is handled by RestKit and saves fine. I have another entity called MyClass, which stores the classes I have selected. This one is only local on the device.

下面是我创建并保存MyClass实体的代码

Here is the code I create and save the MyClass entity

 NSManagedObjectContext *managedObjCtx = [RKManagedObjectStore defaultStore].mainQueueManagedObjectContext;
 MyClass* course = [managedObjCtx insertNewObjectForEntityForName:@"MyClass"];

 .. set the data for course here

 NSError *executeError = nil;
 if(![managedObjCtx save:&executeError]) {
      NSLog(@"Failed to save to data store");
 }

以下是初始化托管数据存储的代码

Here is the code that initialize the managed data store

  // Initialize managed object store
    NSManagedObjectModel *managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
    RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];
    objectManager.managedObjectStore = managedObjectStore;

   /**
     Complete Core Data stack initialization
     */
    [managedObjectStore createPersistentStoreCoordinator];
    NSString *storePath = [RKApplicationDataDirectory() stringByAppendingPathComponent:@"RKMainDb.sqlite"];
    NSString *seedPath = [[NSBundle mainBundle] pathForResource:@"RKSeedDatabase" ofType:@"sqlite"];
    NSError *error;
    NSPersistentStore *persistentStore = [managedObjectStore addSQLitePersistentStoreAtPath:storePath fromSeedDatabaseAtPath:seedPath withConfiguration:nil options:nil error:&error];
    NSAssert(persistentStore, @"Failed to add persistent store with error: %@", error);

    // Create the managed object contexts
    [managedObjectStore createManagedObjectContexts];

    // Configure a managed object cache to ensure we do not create duplicate objects
    managedObjectStore.managedObjectCache = [[RKInMemoryManagedObjectCache alloc] initWithManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];

看起来保存成功，在MyClasseTableViewController中，我可以读取保存的MyClass条目。但是，在我关闭应用程序，然后重新重新启动。 MyClassTableViewController为空，因为获取的结果为空。我使用SQLiteBrowser打开sqlite文件，MyClass表为空。看起来MyClass实体只保存在缓存中，但不在持久存储中。我需要调用RestKit提供的一些API来保存它吗？我试图通过文档阅读，但找不到它。请帮助。

It appears the save is successful and in the MyClasseTableViewController I could read the saved MyClass entries. However after I close the app and restart again. The MyClassTableViewController is empty, because the fetched results is empty. I opened the sqlite file using SQLiteBrowser and the MyClass table is empty. Looks like the MyClass entities are only saved in the cache but not in the persistent store. Do I need to call some API provided by RestKit to save it? I tried to read through the doc but could not find it. Please help.

推荐答案

感谢Tom的领导，我发现RestKit有NSManagedObjectContext（RKAdditions），它有一个方法：

Thanks for the lead by Tom, I found that RestKit has NSManagedObjectContext (RKAdditions), which has a method:

- (BOOL)saveToPersistentStore:(NSError **)error

是的，它有处理嵌套的受管对象上下文的逻辑。
这是新的代码工作，只是一行更改，但花了很多时间来找到正确的调用：（

Yes it does have logic to handle nested managed object context. Here is the new code that works, just one line change, but took a lot of time to find the right call :(

#import "NSManagedObjectContext+RKAdditions.h"
     NSManagedObjectContext *managedObjCtx = [RKManagedObjectStore defaultStore].mainQueueManagedObjectContext;
     MyClass* course = [managedObjCtx insertNewObjectForEntityForName:@"MyClass"];

     .. set the data for course here

     NSError *executeError = nil;
     if(![managedObjCtx saveToPersistentStore:&executeError]) {
          NSLog(@"Failed to save to data store");
     }

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