Foreign key relationship mapping with RestKit - ios

Question

I'm totally new to RestKit and am struggling somewhat.
JSON:
{
"teams": [
{
"id": 1,
"name": "Team A"
},
{
"id": 2,
"name": "Team B"
}
],
"users": [
{
"id": 1,
"name": "cameron",
"teamId": 1
},
{
"id": 2,
"name": "paul",
"teamId": 2
}
]
}
CoreData:
#interface Team : NSManagedObject
#property (nonatomic, retain) NSNumber * teamId;
#property (nonatomic, retain) NSString * name;
#end
#interface User : NSManagedObject
#property (nonatomic, retain) NSNumber * userId;
#property (nonatomic, retain) NSString * name;
#property (nonatomic, retain) Team * team;
#end
My application logic looks like this:
// team mapping
RKEntityMapping *teamMapping = [RKEntityMapping mappingForEntityForName:#"Team" inManagedObjectStore:[RKManagedObjectStore defaultStore]];
teamMapping.identificationAttributes = #[#"teamId"];
[teamMapping addAttributeMappingsFromDictionary:#{
#"id": #"teamId",
#"name": #"name"
}];
// Register our mappings with the provider
RKResponseDescriptor *teamResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:teamMapping
pathPattern:nil
keyPath:#"teams"
statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[self.objectManager addResponseDescriptor:teamResponseDescriptor];
// user mapping
RKEntityMapping *userMapping = [RKEntityMapping mappingForEntityForName:#"User" inManagedObjectStore:[RKManagedObjectStore defaultStore]];
userMapping.identificationAttributes = #[#"userId"];
[userMapping addAttributeMappingsFromDictionary:#{
#"id": #"userId",
#"name": #"name"
}];
// Register our mappings with the provider
RKResponseDescriptor *userResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:userMapping
pathPattern:nil
keyPath:#"users"
statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[self.objectManager addResponseDescriptor:userResponseDescriptor];
I can't for the life of me work out how to get RestKit to populate the team Property of the user objects.
I've look at so many posts but nothing I try works, is this not a usual use case?
Does anyone know how to do this, help would be very appreciated!
Thanks.

Answer 1

You need to add a transient attribute to your User entity which holds the associated teamId. This needs to be added to your userMapping.
Then, you need to add a relationship definition to your userMapping:
[userMapping addConnectionForRelationship:#"team" connectedBy:#{ #"teamId": #"teamId" }];
This gives RestKit the information it needs to make the connection and instructs it to make the connection as part of the mapping operation.