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我在获取属性方面面临一个大问题。

我在模型中有这个实体：

EntityDetail    
Attributes:
NSString: idd_info
[...]
Fetched Property:
Name: info Destination: EntityInfo Predicate: idd==$FETCH_SOURCE.idd_info


EntityInfo
Attributes:
NSString: idd
NSString: title
[...]

这样我可以在需要的时候获取相关的EntityInfo：

[[detail.info objectAtIndex:0] title]

由于解析过程中的性能原因，我更喜欢这种方法而不是配置常规关系。

如果我使用 Apple 生成的 CoreData 样板来设置堆栈，一切正常，我可以成功使用 fetched 属性。但是，如果我使用 RKManagedObjectStore 类提供的 RestKit 实现，则 fetched 属性不起作用。这是错误：

由于未捕获的异常“NSUnknownKeyException”而终止应用程序，原因：“[<_NSObjectID_48_15 0x1a2f9ac0> valueForUndefinedKey:]：此类与键 idd_info 的键值编码不兼容。”

似乎 $FETCH_SOURCE 解析为 NSObjectID 而不是 NSObject 本身。而且，显然，idd_info 属性没有在该类上定义。

谷歌搜索我发现了将 fetchRequest 上的 resultType 设置为 NSManagedObjectResultType 的可能性。这是 Apple 文档中所述的默认行为。那么为什么 RestKit 0.20.3 改用 NSManagedObjectIDResultType 呢？使用 RestKit 0.10 一切正常...

这是一个已知的错误吗？如何将获取的属性强制为 NSManagedObjectResultType ？

这是我使用 RKManagedObjectStore 设置持久存储和创建托管对象上下文的方式。我在应用程序委托中，_managedObjectModel _managedObjectStore _managedObjectContext 是整个应用程序中使用的单例变量）。

NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"MyApp" ofType:@"momd"]];        
_managedObjectModel= [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL] mutableCopy]; 
_managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:_managedObjectModel];     
[_managedObjectStore createPersistentStoreCoordinator];


NSString *storePath = [[self docDir] stringByAppendingPathComponent::@"MyApp.sqlite"];    
NSDictionary *options = @{ NSSQLitePragmasOption : @{@"journal_mode" : @"DELETE"} };    
NSPersistentStore __unused *persistentStore = [_managedObjectStore addSQLitePersistentStoreAtPath:storePath fromSeedDatabaseAtPath:nil withConfiguration:nil options:options error:&error];    
NSAssert(persistentStore, @"Failed to add persistent store: %@", error);


[_managedObjectStore createManagedObjectContexts];        
[RKManagedObjectStore setDefaultStore:_managedObjectStore];    
[_managedObjectStore.mainQueueManagedObjectContext setUndoManager:nil];    
_managedObjectContext = _managedObjectStore.mainQueueManagedObjectContext;

谢谢你。

更新 1：

如果我使用：

_managedObjectContext = _managedObjectStore.persistentStoreManagedObjectContext;

代替：

_managedObjectContext = _managedObjectStore.mainQueueManagedObjectContext;

在启动时的应用程序委托中，该问题不会发生并且获取的属性工作正常，但它仍然在映射期间发生。

这就是我设置映射的方式。

RKObjectManager* objectManager = [RKObjectManager managerWithBaseURL:baseURL];

[RKMIMETypeSerialization registerClass:[RKXMLReaderSerialization class] forMIMEType:@"application/xml"];
[[RKObjectManager sharedManager] setAcceptHeaderWithMIMEType:RKMIMETypeTextXML];
[RKObjectManager setSharedManager:objectManager];

RKManagedObjectStore* objectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:appDeleg.managedObjectModel];

[objectStore addSQLitePersistentStoreAtPath:storePath fromSeedDatabaseAtPath:nil withConfiguration:nil options:@{ NSInferMappingModelAutomaticallyOption: @YES,NSMigratePersistentStoresAutomaticallyOption: @YES, NSSQLitePragmasOption: @{@"journal_mode" : @"DELETE"} } error:nil];

[objectStore createManagedObjectContexts];

objectManager.managedObjectStore=objectStore;

[objectManager.HTTPClient setAuthorizationHeaderWithUsername:usernameString password:passwordString]

[... here RKEntityMappings and ResponseDescriptors added to the objectManager ...]

[[RKObjectManager sharedManager]  getObjectsAtPath:remoteBaseAddedPath parameters:nil

    success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {


            [delegate parserDidSuccessParsingData:self];


    } failure:^(RKObjectRequestOperation *operation, NSError *error) {



            [delegate parserDidFailParsingData:self withError:error];

}];

更新 2：

这是映射期间的堆栈跟踪。请注意，我在使用 getter 中获取的属性的对象上有一个瞬态属性，RestKit 调用此 getter 并发生崩溃：

2014-03-20 11:10:53.545 MyApp[15378:f03] D restkit.object_mapping:RKMappingOperation.m:952 Starting mapping operation...
2014-03-20 11:10:53.549 MyApp[15378:60b] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<NSTemporaryObjectID_default 0xcb9a870> valueForUndefinedKey:]: this class is not key value coding-compliant for the key idd_info.'

*** First throw call stack:
(
    0   CoreFoundation                      0x02b021e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x028818e5 objc_exception_throw + 44
    2   CoreFoundation                      0x02b91fe1 -[NSException raise] + 17
    3   Foundation                          0x00f6dc7a -[NSObject(NSKeyValueCoding) valueForUndefinedKey:] + 282
    4   Foundation                          0x00edadfd _NSGetUsingKeyValueGetter + 81
    5   Foundation                          0x00eda437 -[NSObject(NSKeyValueCoding) valueForKey:] + 260
    6   Foundation                          0x00ef9f0a -[NSObject(NSKeyValueCoding) valueForKeyPath:] + 409
    7   Foundation                          0x00eab465 -[NSFunctionExpression expressionValueWithObject:context:] + 1260
    8   CoreData                            0x00728bbc -[NSSQLSimpleWhereIntermediate initWithPredicate:inScope:] + 620
    9   CoreData                            0x007283eb -[NSSQLGenerator generateWhereIntermediatesInContext:] + 187
    10  CoreData                            0x00727dc1 -[NSSQLGenerator generateIntermediatesForFetchInContext:countOnly:] + 673
    11  CoreData                            0x007242f3 -[NSSQLGenerator newSQLStatementForFetchRequest:ignoreInheritance:countOnly:nestingLevel:] + 483
    12  CoreData                            0x00723fb8 -[NSSQLAdapter _newSelectStatementWithFetchRequest:ignoreInheritance:] + 472
    13  CoreData                            0x00723dd0 -[NSSQLAdapter newSelectStatementWithFetchRequest:] + 48
    14  CoreData                            0x00723b91 -[NSSQLCore newRowsForFetchPlan:] + 129
    15  CoreData                            0x0072331d -[NSSQLCore objectsForFetchRequest:inContext:] + 701
    16  CoreData                            0x00722dcf -[NSSQLCore executeRequest:withContext:error:] + 383
    17  CoreData                            0x007227f2 -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 4466
    18  CoreData                            0x0071ff56 -[NSManagedObjectContext executeFetchRequest:error:] + 566
    19  CoreData                            0x00774d86 -[NSManagedObjectContext(_NestedContextSupport) _parentObjectsForFetchRequest:inContext:error:] + 502
    20  CoreData                            0x007f2a14 __82-[NSManagedObjectContext(_NestedContextSupport) executeRequest:withContext:error:]_block_invoke + 676
    21  CoreData                            0x00774b81 internalBlockToNSManagedObjectContextPerform + 17
    22  libdispatch.dylib                   0x032394d0 _dispatch_client_callout + 14
    23  libdispatch.dylib                   0x03226740 _dispatch_barrier_sync_f_invoke + 58
    24  libdispatch.dylib                   0x032263ea dispatch_barrier_sync_f + 89
    25  CoreData                            0x00774b02 _perform + 114
    26  CoreData                            0x007749ae -[NSManagedObjectContext(_NestedContextSupport) executeRequest:withContext:error:] + 238
    27  CoreData                            0x0071ff56 -[NSManagedObjectContext executeFetchRequest:error:] + 566
    28  CoreData                            0x00774d86 -[NSManagedObjectContext(_NestedContextSupport) _parentObjectsForFetchRequest:inContext:error:] + 502
    29  CoreData                            0x007f2a14 __82-[NSManagedObjectContext(_NestedContextSupport) executeRequest:withContext:error:]_block_invoke + 676
    30  CoreData                            0x00774b81 internalBlockToNSManagedObjectContextPerform + 17
    31  libdispatch.dylib                   0x032394d0 _dispatch_client_callout + 14
    32  libdispatch.dylib                   0x03228439 _dispatch_barrier_sync_f_slow_invoke + 80
    33  libdispatch.dylib                   0x032394d0 _dispatch_client_callout + 14
    34  libdispatch.dylib                   0x03227726 _dispatch_main_queue_callback_4CF + 340
    35  CoreFoundation                      0x02b6743e __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 14
    36  CoreFoundation                      0x02aa85cb __CFRunLoopRun + 1963
    37  CoreFoundation                      0x02aa79d3 CFRunLoopRunSpecific + 467
    38  CoreFoundation                      0x02aa77eb CFRunLoopRunInMode + 123
    39  GraphicsServices                    0x0392c5ee GSEventRunModal + 192
    40  GraphicsServices                    0x0392c42b GSEventRun + 104
    41  UIKit                               0x012bff9b UIApplicationMain + 1225
    42  MyApp                               0x001a186c main + 76
    43  libdyld.dylib                       0x0346e701 start + 1
    44  ???                                 0x00000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
4

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