Question

I am using Restkit Version 0.2 to map JSON results to Objective-C Objects. The JSON received looks like this:

{
"result": {
    "errorCode": 0,
    "errorMsg": "ok",
    "data": {
        "orderitems": [
            {
                "id": "46",
                "o_order_id": "15",
                "p_product_id": "7",
                "t_event_id": "1",
                "quantity": "1",
                "price": "4.5",
                "name": "Name1",
                "unit": "something1",
                "image": "images/7.png"
            },
            {
                "id": "47",
                "o_order_id": "15",
                "p_product_id": "10",
                "t_event_id": "1",
                "quantity": "1",
                "price": "3.99",
                "name": "Name2",
                "unit": "something2",
                "image": "images/10.png"
            }
        ]
    }
}
}

I defined the following mapping:

RKObjectMapping *oiMapping = [RKObjectMapping mappingForClass:[OrderItem class]];
[oiMapping mapKeyPathsToAttributes:@"p_product_id", @"productID", @"name", @"name",  @"t_event_id", @"eventID",  @"quantity", @"quantity",  nil];
[objectManager.mappingProvider setMapping:oiMapping forKeyPath:@"result.data.orderitems"];

RKObjectMapping *takeOrderResultMapping = [RKObjectMapping mappingForClass:[TakeOrderResult class]];
[takeOrderResultMapping mapKeyPathsToAttributes:@"errorCode", @"errorCode", @"errorMsg", @"errorMessage", nil];
[takeOrderResultMapping mapRelationship:@"orderitems" withMapping:oiMapping];

[objectManager.mappingProvider setMapping:takeOrderResultMapping forKeyPath:@"result"];
takeOrderResultMapping.rootKeyPath = @"result";
[[RKObjectManager sharedManager].mappingProvider setErrorMapping:takeOrderResultMapping]; 

And finally, the TakeOrderResult class is defined like this:

@interface TakeOrderResult : NSObject
@property (strong, nonatomic) NSNumber *errorCode;
@property (strong, nonatomic) NSString *errorMessage;
@property (strong, nonatomic) NSSet *orderitems;
@end

This more or less works – however, what Restkit returns is the an array of 3 Objects. The first object is an instance of TakeOrderResult with an empty set “orderitems”. The next two objects are instances of OrderItems.

It would be great if somebody could help me and point out why I don’t get 1 object, i.e. an instance of TakeOrderResult where “orderitems” is a set of two objects / two OrderItems.

Answer 1

Your mapping is slightly off.
The reason you’re getting 3 objects is you’re adding both mappings to the mapping provider.
The reason the “orderitems” is an empty set is because it doesn’t know how to find the orderitems.

I have no idea if it works, but i’d try the following.
Don’t add your oiMapping to the mapping provider.
And instead of:

[takeOrderResultMapping mapRelationship:@”orderitems” withMapping:oiMapping];

try:

[takeOrderResultMapping addRelationshipMappingWithSourceKeyPath:@”data.orderitems” mapping:oiMapping];