Error: 'Unable to add mapping for keyPath news, one already exists...'

Question

I am using RestKit to get data from a Restful Web Service. With a flat file it works great. My problem starts if I want to get the response to a nested JSON.

My JSON looks like:

[{"homename":"Alien","created_at":"2011-09-15T12:46:37Z", "updated_at":"2011-09-15T12:46:37Z","gametype":"Final match", "id":1,"date":"2016-10-10","guestname":"Predator", "news":[{"minute":null,"created_at":"2011-09-15T13:19:51Z","player":null,"title":"Title", "updated_at":"2011-09-15T13:19:51Z","id":1,"bodytext":"News","game_id":1},{"minute":null,"created_at":"2011-09-15T13:22:06Z","player":null,"title":"New news","updated_at":"2011-09-15T13:22:06Z","id":2,"bodytext":"Old socks","game_id":1},{"minute":null,"created_at":"2011-09-15T13:26:32Z","player":null,"title":"another title","updated_at":"2011-09-15T13:26:32Z","id":3,"bodytext":"Bodytext 2","game_id":1},{"minute":null,"created_at":"2011-09-22T12:35:19Z","player":null,"title":"comment","updated_at":"2011-09-22T12:35:19Z","id":4,"bodytext":"body of the comment","game_id":1}]}]

With the following code I would like to get the data mapped.

RKLogConfigureByName("RestKit/Network*", RKLogLevelTrace);
// Initialize RestKit
RKObjectManager* objectManager = [RKObjectManager objectManagerWithBaseURL:@"http://X.X.X.X:3000"];

// Enable automatic network activity indicator management
//objectManager.client.requestQueue.showsNetworkActivityIndicatorWhenBusy = YES;


RKObjectMapping* newsMapping = [RKObjectMapping mappingForClass:[News class]];
[newsMapping mapKeyPath:@"id" toAttribute:@"id"];
[newsMapping mapKeyPath:@"minute" toAttribute:@"minute"];
[newsMapping mapKeyPath:@"title" toAttribute:@"title"];
[newsMapping mapKeyPath:@"bodytext" toAttribute:@"bodytext"];

// Setup our object mappings
RKObjectMapping* gameMapping = [RKObjectMapping mappingForClass:[Game class]];
//  [gameMapping mapKeyPath:@"id" toAttribute:@"id"];

[gameMapping mapKeyPath:@"guestname" toAttribute:@"guestname"];
[gameMapping mapKeyPath:@"homename" toAttribute:@"homename"];
[gameMapping mapKeyPath:@"date" toAttribute:@"date"];
[gameMapping mapKeyPath:@"gametype" toAttribute:@"gametype"];
[gameMapping mapKeyPath:@"news" toAttribute:@"news"];

[gameMapping mapKeyPath:@"news" toRelationship:@"news" withMapping:newsMapping];
[objectManager.mappingProvider setMapping:gameMapping forKeyPath:@"games"];

The statement [gameMapping mapKeyPath:@"news" toRelationship:@"news" withMapping:newsMapping]; raises an exception during runtime and I cannot figure out why:

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Unable to add mapping for keyPath news, one already exists...'

Does someone see what I am doing wrong? Is the relation wrong for a 1:n relation?

Answer 1

You have two mappings for news keyPath:

[gameMapping mapKeyPath:@"news" toAttribute:@"news"];

and

[gameMapping mapKeyPath:@"news" toRelationship:@"news" withMapping:newsMapping];

remove the first and see if it helps.

Cheers.