RestKit - the entity (null) is not key value coding-compliant for the key "id"

Question

I have a strange problem when trying to upload image with RestKit. I have studied similar questions but none of them could fix my problem.

In my application user can create comment on some Task.

So I have setup both RKEntityMapping and RKObjectMapping mapping, like this:

- (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;
}

I have define, URL_COMMENTS like this:

#define URL_COMMENTS @"/comments"

To get objects, I call:

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

And it is working perfectly, without any error.

If I need to create new comment, I call:

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


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

It is working perfect too, without any error.

But when I need to create a comment with image attachment, I call:

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];

Now here is the problem, comment is created on server side successfully but application is terminated with error:

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

Here is some more 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".'

I think it might related to some URL issue. I am sending request at URL_COMMENTS which is defined as #define URL_COMMENTS @"/comments"

I have tried by sending request at comments (without beginning /) and set pathPattern in responseDescriptor as /comments (with beginning /)

I also have tried by sending request /comments (with beginning /) and set pathPattern in responseDescriptor as comments (without beginning /)

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

Also tried by setting both places same with or without / but nothing is working.

I had previously fixed this error by some combination of / in path whenever I needed to call AFNetworking method. But don't know why this error is occuring.

Please help

Answer 1

Because the comment is a managed object and you are asking RestKit to treat it like a plain object. So, RestKit is trying to create a new instance in which to set the response data and failing on the creation.

You should be using managedObjectRequestOperationWithRequest:managedObjectContext:success:failure: to create the operation so that it has a reference to the MOC and can properly create the entity instance (though it should find the existing entity instance in this case).