RestKit - 实体（null）不是键值“id”的键值编码兼容

Question

尝试使用RestKit上传图像时，我遇到了一个奇怪的问题。 我研究过类似的问题，但没有一个能解决我的问题。

在我的应用程序中，用户可以创建一些任务的注释

所以我设置了RKEntityMapping和RKObjectMapping映射，如下所示：

- (RKEntityMapping *)commentsMapping {

    RKEntityMapping *commentsMapping = [RKEntityMapping mappingForEntityForName:@"DBComments" inManagedObjectStore:objectManager.managedObjectStore];
    commentsMapping.setDefaultValueForMissingAttributes = NO;
    commentsMapping.identificationAttributes = @[@"id"];
    [commentsMapping setModificationAttributeForName:@"updated_at"];

    [commentsMapping addAttributeMappingsFromDictionary:@{
                                                          @"body" : @"body",
                                                          @"created_at" : @"created_at",
                                                          @"id" : @"id",
                                                          @"parent_id" : @"parent_id",
                                                          @"send_email" : @"send_email",
                                                          @"updated_at" : @"updated_at",
                                                          @"user.id" : @"user_id",
                                                          @"user.name" : @"user_name",
                                                          }];

    [commentsMapping addRelationshipMappingWithSourceKeyPath:@"attachments" mapping:[self attachmentsMapping]];

    return commentsMapping;
}


- (RKObjectMapping *)commentsRequestMapping {
    RKObjectMapping *commentsRequestMapping = [RKObjectMapping requestMapping];
    [commentsRequestMapping addAttributeMappingsFromDictionary:@{
                                                                 @"body" : @"body",
                                                                 @"created_at" : @"created_at",
                                                                 @"id" : @"id",
                                                                 @"parent_id" : @"parent_id",
                                                                 @"send_email" : @"send_email",
                                                                 @"updated_at" : @"updated_at",
                                                                 @"user.id" : @"user_id",
                                                                 @"user.name" : @"user_name",
                                                                 }];

    return commentsRequestMapping;
}

我已经定义了这样的URL_COMMENTS：

#define URL_COMMENTS @"/comments"

为了获得对象，我打电话给：

[[RKObjectManager sharedManager] getObjectsAtPath:URL_COMMENTS
                                       parameters:@{@"item_id": parentID}
                                          success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
                                              KLog(@"success");
                                          }
                                          failure:^(RKObjectRequestOperation *operation, NSError *error) {
                                              KLog(@"fail");
                                          }];

它运行正常，没有任何错误。

如果我需要创建新评论，我打电话：

[[RKObjectManager sharedManager] postObject:comment path:URL_COMMENTS
                                 parameters:nil
                                    success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
                                        KLog(@"success");


                                } failure:^(RKObjectRequestOperation *operation, NSError *error) {
                                    KLog(@"fail");
                                }];

它也很完美，没有任何错误。

但是当我需要用图像附件创建评论时，我打电话给：

NSMutableURLRequest *request =[[RKObjectManager sharedManager] multipartFormRequestWithObject:comment
                                                                                           method:RKRequestMethodPOST
                                                                                             path:URL_COMMENTS
                                                                                       parameters:nil
                                                                        constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
                                                                            [formData appendPartWithFileData:UIImageJPEGRepresentation(image, 0.7)
                                                                                                        name:@"photo"
                                                                                                    fileName:@"photo.jpg"
                                                                                                    mimeType:@"image/jpg"];
                                                                        }];

    RKObjectRequestOperation *operation = [[RKObjectManager sharedManager] objectRequestOperationWithRequest:request
                                                                                                     success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
                                                                                                         // Success handler.
                                                                                                         KLog(@"%@", [mappingResult firstObject]);

                                                                                                     } failure:^(RKObjectRequestOperation *operation, NSError *error) {
                                                                                                         KLog(@"fail");
                                                                                                     }];

    [operation start];

现在问题是，在服务器端成功创建了注释，但应用程序因错误而终止：

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<DBComments 0x11e01400> valueForUndefinedKey:]: the entity (null) is not key value coding-compliant for the key "id".'

这里有一些Log

D restkit.object_mapping:RKMapperOperation.m:377 Executing mapping operation for representation: {
    body = "Test attachment";
    "created_at" = "2014-04-02T15:41:00+02:00";
    id = 13379;
    "parent_id" = 291160;
    "updated_at" = "2014-04-02T15:41:00+02:00";
    user =     {
        id = 12891;
        name = "Rehmat Qadir";
    };
}
 and targetObject: (null)


D restkit.object_mapping:RKMapperOperation.m:300 Found mappable data at keyPath '': {
    body = "Test attachment";
    "created_at" = "2014-04-02T15:41:00+02:00";
    id = 13379;
    "parent_id" = 291160;
    "updated_at" = "2014-04-02T15:41:00+02:00";
    user =     {
        id = 12891;
        name = "Rehmat Qadir";
    };
}



CoreData: error: Failed to call designated initializer on NSManagedObject class 'DBComments' 
2014-04-02 18:41:00.269 MeetingKing[14722:f03] D restkit.object_mapping:RKMapperOperation.m:231 Asked to map source object {
    body = "Test attachment";
    "created_at" = "2014-04-02T15:41:00+02:00";
    id = 13379;
    "parent_id" = 291160;
    "updated_at" = "2014-04-02T15:41:00+02:00";
    user =     {
        id = 12891;
        name = "Rehmat Qadir";
    };
} with mapping <RKEntityMapping:0xc686500 objectClass=DBComments propertyMappings=(
    "<RKAttributeMapping: 0xc6877d0 user.id => user_id>",
    "<RKAttributeMapping: 0xc6875c0 id => id>",
    "<RKAttributeMapping: 0xc6875e0 send_email => send_email>",
    "<RKAttributeMapping: 0xc687610 created_at => created_at>",
    "<RKAttributeMapping: 0xc687630 parent_id => parent_id>",
    "<RKAttributeMapping: 0xc6877e0 updated_at => updated_at>",
    "<RKAttributeMapping: 0xc687850 user.name => user_name>",
    "<RKAttributeMapping: 0xc687920 body => body>",
    "<RKRelationshipMapping: 0xc688b90 attachments => attachments>"
)>


D restkit.object_mapping:RKMappingOperation.m:952 Starting mapping operation...


*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<DBComments 0x11e01400> valueForUndefinedKey:]: the entity (null) is not key value coding-compliant for the key "id".'

我认为它可能与某些URL问题有关。 我在URL_COMMENTS发送请求，该请求定义为#define URL_COMMENTS @"/comments"

我试过通过发送请求comments （没有开始/）并在responseDescriptor中将pathPattern设置为/comments （带开头/）

我也尝试过发送请求/comments （带开头/）并在responseDescriptor设置pathPattern作为comments （不包括开头/）

[RKResponseDescriptor responseDescriptorWithMapping:[self commentsMapping]
                                                                                                  method:RKRequestMethodGET
                                                                                             pathPattern:URL_COMMENTS
                                                                                                 keyPath:@"" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)],

也尝试通过设置两个相同的地方有或没有/但没有任何工作。

我以前曾通过一些组合固定此错误/路径每当我需要调用AFNetworking方法。 但不知道为什么会发生这种错误。

请帮忙

Answer 1

因为注释是一个托管对象，并且您要求RestKit将其视为普通对象。 因此，RestKit正在尝试创建一个新实例，在该实例中设置响应数据并在创建时失败。

您应该使用managedObjectRequestOperationWithRequest:managedObjectContext:success:failure:创建操作以便它具有对MOC的引用并且可以正确地创建实体实例（尽管在这种情况下它应该找到现有的实体实例）。