objective c - RestKit nested relationships -

working restkit, i'm trying map following json.

{   "userid": 1,   "collections": [     {       "collectionid": 120,       "friends": [         {           "friendid": 6,           "orders": [             {               "orderid": 1,               "name": "small"             }           ]         }       ]     },     {       "collectionid": 123,       "friends": [         {           "friendid": 6,           "orders": [             {               "orderid": 2,               "name": "medium"             }           ]         }       ]     }   ] } 

i'm utilising restkit , magicalrecord - setup code, mapping , relationships below

nsurl *modelurl = [nsurl fileurlwithpath:[[nsbundle mainbundle] pathforresource:@"model" oftype:@"momd"]]; nsmanagedobjectmodel *managedobjectmodel = [[[nsmanagedobjectmodel alloc] initwithcontentsofurl:modelurl] mutablecopy]; rkmanagedobjectstore *managedobjectstore = [[rkmanagedobjectstore alloc] initwithmanagedobjectmodel:managedobjectmodel]; nsstring *storepath = [rkapplicationdatadirectory() stringbyappendingpathcomponent:@"db.sqlite"];  [managedobjectstore addsqlitepersistentstoreatpath:storepath fromseeddatabaseatpath:nil withconfiguration:nil options:nil error:nil]; [managedobjectstore createmanagedobjectcontexts];  // configure magicalrecord use restkit's core data stack [nspersistentstorecoordinator mr_setdefaultstorecoordinator:managedobjectstore.persistentstorecoordinator]; [nsmanagedobjectcontext mr_setrootsavingcontext:managedobjectstore.persistentstoremanagedobjectcontext]; [nsmanagedobjectcontext mr_setdefaultcontext:managedobjectstore.mainqueuemanagedobjectcontext];  rkobjectmanager *objectmanager = [rkobjectmanager managerwithbaseurl:[nsurl urlwithstring:@"http://127.0.0.1:3500"]]; objectmanager.managedobjectstore = managedobjectstore;  rkentitymapping *appmapping = [rkentitymapping mappingforentityforname:@"app" inmanagedobjectstore:managedobjectstore]; appmapping.identificationattributes = @[ @"userid" ];  rkentitymapping *collectionmapping = [rkentitymapping mappingforentityforname:@"collection" inmanagedobjectstore:managedobjectstore]; collectionmapping.identificationattributes = @[ @"collectionid" ]; [collectionmapping addattributemappingsfromarray:@[@"collectionid"]];  rkentitymapping *friendmapping = [rkentitymapping mappingforentityforname:@"friend" inmanagedobjectstore:managedobjectstore]; friendmapping.identificationattributes = @[ @"friendid" ]; [friendmapping addattributemappingsfromarray:@[@"friendid"]];  rkentitymapping *ordermapping = [rkentitymapping mappingforentityforname:@"order" inmanagedobjectstore:managedobjectstore]; ordermapping.identificationattributes = @[ @"orderid" ]; [ordermapping addattributemappingsfromarray:@[@"orderid", @"name"]];   rkrelationshipmapping *appcollectionrelationship = [rkrelationshipmapping relationshipmappingfromkeypath:@"collections" tokeypath:@"collections" withmapping:collectionmapping]; [appmapping addpropertymapping:appcollectionrelationship];  rkrelationshipmapping *collectionfriendrelationship = [rkrelationshipmapping relationshipmappingfromkeypath:@"friends" tokeypath:@"friends" withmapping:friendmapping]; [collectionmapping addpropertymapping:collectionfriendrelationship];  rkrelationshipmapping *friendsorderrelationship = [rkrelationshipmapping relationshipmappingfromkeypath:@"orders" tokeypath:@"orders" withmapping:ordermapping]; [friendsorderrelationship setassignmentpolicy:rkunionassignmentpolicy]; [friendmapping addpropertymapping:friendsorderrelationship]; 

then, querying /test route on api (which outputs json block above) below console out...

rkresponsedescriptor *responsedescriptor = [rkresponsedescriptor responsedescriptorwithmapping:appmapping method:rkrequestmethodany pathpattern:nil keypath:nil statuscodes:rkstatuscodeindexsetforclass(rkstatuscodeclasssuccessful)]; [objectmanager addresponsedescriptor:responsedescriptor];  [objectmanager getobjectsatpath:@"/test" parameters:nil success:^(rkobjectrequestoperation *operation, rkmappingresult *mappingresult) {      app *app = [mappingresult firstobject];     (collection *collection in app.collections) {         nslog(@"collectionid = %@", collection.collectionid);         (friend *friend in collection.friends) {             nslog(@"friendid = %@", friend.friendid);             (order *order in friend.orders) {                 nslog(@"name = %@", order.name);             }         }     } } failure:^(rkobjectrequestoperation *operation, nserror *error) {}]; 

provides following output - notice both name's medium, not 1 small , other medium.

collectionid = 120 friendid = 6 name = medium name = small collectionid = 123 friendid = 6 name = medium name = small 

why happening? i'm going guess it's because both friend id's same, though they're under different collections...

this because have identificationattributes = @[ @"friendid" ]; , default relationship connection rule relationships rather replacement. so, second mapping finds friend created first mapping , replaces order relationship contents.

you can't realistically change unique identifier based on json show, might want examine (in relation object graph requirements).

also / alternatively, see this answer details of how change relationship assignment policy original relationship contents aren't lost.