使用RESTkit从JSON从NSManagedObject映射NSString的数组

Question

一些先决条件：

JSON正文：

"returnCode":{“messages”[], "something":1}

应该映射到：

@interface ReturnCodeEntity : NSMutableObject

@property (nonatomic, retain) id messages; // Should be defined as Transformable?
@property (nonatomic, retain) NSString * something;

题：

嗨，我想这是两个问题：

1. 为核心数据实体中的“消息”数组定义适当的类型
2. 使用RKEntityMapping类映射此数组

现在，映射操作完成后，我得到一个异常：

2014-04-10 12:12:05.661 [4811:3f07] D restkit.object_mapping:RKMappingOperation.m:929 Finished mapping operation successfully...
2014-04-10 12:12:05.661 [4811:3f07] -[__NSDictionaryM _stateFlags]: unrecognized selector sent to instance 0x10990d0b0
2014-04-10 12:12:08.786 [4811:3f07] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSDictionaryM _stateFlags]: unrecognized selector sent to instance 0x10990d0b0'
 First throw call stack:
(
    0   CoreFoundation                      0x0000000102af8495 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000010285799e objc_exception_throw + 43
    2   CoreFoundation                      0x0000000102b8965d -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
    3   CoreFoundation                      0x0000000102ae9d8d ___forwarding___ + 973
    4   CoreFoundation                      0x0000000102ae9938 _CF_forwarding_prep_0 + 120
    5   CoreData                            0x00000001008ec8f8 -[NSRelationshipDescription(_NSInternalMethods) _nonPredicateValidateValue:forKey:inObject:error:] + 232
    6   CoreData                            0x00000001008eba27 -[NSManagedObject(_NSInternalMethods) _validateValue:forProperty:andKey:withIndex:error:] + 375
    7   CoreData                            0x00000001009651d7 -[NSManagedObject validateValue:forKey:error:] + 135
    8   Foundation                          0x0000000100f19ed5 -[NSObject(NSKeyValueCoding) validateValue:forKeyPath:error:] + 336
    9                                       0x0000000100212cb5 -[RKMappingOperation validateValue:atKeyPath:] + 341
    10                                      0x000000010021334d -[RKMappingOperation shouldSetValue:forKeyPath:usingMapping:] + 861
    11                                      0x00000001002177dd -[RKMappingOperation mapOneToOneRelationshipWithValue:mapping:] + 1661
    12                                      0x000000010021b14a -[RKMappingOperation applyRelationshipMappings] + 6186
    13                                      0x000000010021d2f6 -[RKMappingOperation main] + 4006
    14  Foundation                          0x0000000100f2bd34 -[__NSOperationInternal _start:] + 623
    15                                      0x000000010020ca5e -[RKMapperOperation mapRepresentation:toObject:atKeyPath:usingMapping:metadata:] + 1886
    16                                      0x000000010020b3ff -[RKMapperOperation mapRepresentation:atKeyPath:usingMapping:] + 1871
    17                                      0x000000010020dd75 -[RKMapperOperation mapRepresentationOrRepresentations:atKeyPath:usingMapping:] + 805
    18                                      0x000000010020e5a8 -[RKMapperOperation mapSourceRepresentationWithMappingsDictionary:] + 1944
    19                                      0x000000010020eef5 -[RKMapperOperation main] + 1365

在groups.google.com上进行了讨论，但最终得到了解决方法。

谢谢你的建议。

编辑

我在身上引入了斑疹伤寒。 是的，此帖子中缺少分号

{"returnCode":{"messages":[], "something":1}}

我在模型中做了一些更改，因此ReturnCodeEntity包含NSSet，该NSSet引用了将消息存储在'text'属性中的新类型MessageEntity：

@interface ReturnCodeEntity : NSMutableObject

@property (nonatomic, retain) NSString * something;
@property (nonatomic, retain) NSSet *messages; // --> relationship 1 to many MessageEntitie's
@end

@interface ReturnCodeEntity (CoreDataGeneratedAccessors)

- (void)addMessagesObject:(MessageEntity *)value;
- (void)removeMessagesObject:(MessageEntity *)value;
- (void)addMessages:(NSSet *)values;
- (void)removeMessages:(NSSet *)values;
@end

@interface MessageEntity : NSMutableObject

@property (nonatomic, retain) NSString * text;
@property (nonatomic, retain) ReturnCodeEntity *returnCode; // --> relationship 1 to 1 ReturnCodeEntity
@end

我已经为MessageEntity创建了映射：

RKEntityMapping *mapping = [RKEntityMapping mappingForEntityForName:@"MessageEntity" inManagedObjectStore:managedObjectStore];
[mapping addPropertyMapping:[RKAttributeMapping attributeMappingFromKeyPath:nil toKeyPath:@"text"]];
mapping.identificationAttributes = @[ @"text" ];

...并将其添加到returnCodeEntityMapping中

[returnCodeEntityMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"messages" toKeyPath:@"messages" withMapping:messageApiMapping]]; 

跟踪显示映射在层次结构中是成功的，但后来在RKMappingOperation.m中的*-（BOOL）validateValue：（id *）value atKeyPath：（NSString ）keyPath方法中崩溃

success = [self.destinationObject validateValue:value forKeyPath:keyPath error:&validationError];

谢谢Wain的帮助。

Answer 1

我的问题是为MessageEntity映射而不是RKAttributeMapping实例化RKObjectMapping。

这是因为我已经从另一个使用[RKObjectMapping requestMapping]的实体类中复制了代码（由于请求）。 我必须添加（从Restkit用户的角度来看）使用RKObjectMapping进行请求是令人困惑的，即使我不需要使用RKAttributeMapping。 我在这里更喜欢一致的api（RKAttributeMapping）。 但是无论如何，Restkit是避免手动解析/映射的好工具。

Wain的解决方案很有用

RestKit：映射字符串的JSON数组