RestKit RKObjectMapping of a list - ios

Question

I am new to RestKit and am trying to map a json object that contains an array of objects my model. I have debugged and found that the response hits my server --> json is return --> RestKit says the mapping was successful and that I have 1 object mapped... However, the errorCode field and the array of businesses (bList) are both null when I do BusinessObjectModel *response = result.array.firstObject;
in the OnSuccessBlock.
Json:
{
"bList":
[
{
"id": 1,
"name": "aName",
"owner": 1,
"category": 1,
}
{
"id": 2,
"name": "aName2",
"owner": 1,
"category": 1,
}
],
"errorCode": 0
}
Want to map this Json to this objective c object:
BussinessObjectModel Object Mapping:
RKObjectMapping *responseMapping = [RKObjectMapping mappingForClass:[BusinessObjectModel class]];
[responseMapping addAttributeMappingsFromDictionary:#{
#"id": #"business_id",
#"name": #"business_name",
}];
return responseMapping;
BModel:
#interface bModel : NSObject
#property (nonatomic, copy) NSNumber *errorCode;
#property (nonatomic, copy) NSMutableArray *bList;
+(RKObjectMapping *) getMapping;
#end
BModel Object Mapping:
RKObjectMapping *bMapping = [BusinessObjectModel getMapping];
RKObjectMapping *buslstMapping = [RKObjectMapping mappingForClass:[BModel class]];
[buslstMapping addAttributeMappingsFromDictionary:#{#"errorCode": #"errorCode"}];
// Define the relationship mapping
[buslstMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:nil
toKeyPath:nil
withMapping:bussinessMapping]];
return buslstMapping;
Descriptor looks as follows:
RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:ResponseMapping method:RKRequestMethodAny pathPattern:nil keyPath:#"bList" statusCodes:nil];
EDIT
I want to map the above Json to :
#interface bModel : NSObject
#property (nonatomic, copy) NSNumber *errorCode;
#property (nonatomic, copy) NSMutableArray *bList;
#end
Where bList is an array of the following object:
#interface Business : NSObject
#property (nonatomic, copy) NSNumber *id;
#property (nonatomic, copy) NSString *name;
#property (nonatomic, copy) NSNumber *id;
#property (nonatomic, copy) NSNumber *id;
#end
I guess the question is how do I do nested relationships (what would the Response Descriptor have to be for the above relationship)?

Answer 1

Great to see that your using RestKit. Your first helper will be the logging that RestKit provides. Add this line of code do your AppDelegate and watch the console for errors.
// The * will send everything RestKit does to the console
// Replace the * with the module you want to check (Network/CoreData/...)
RKLogConfigureByName("RestKit/*", RKLogLevelTrace);
When looking at your JSON you want to get the objects from the keyPath "bList" on the one hand and on the other hand the error code or message when something goes wrong. RestKit provides a build in error handling to get that information out of your JSON.
Init the RKObjectMapping for the RKErrorMessage class and add a RKResponseDescriptor to your requests with the right keyPaths including the range of status codes (here using client errors). RestKit will automatically detect the error code (when sent within the header) and apply the mapping to get the content of the error message.
// Init error mapping
RKObjectMapping *errorMapping = [RKObjectMapping mappingForClass:[RKErrorMessage class]];
[errorMapping addPropertyMapping:[RKAttributeMapping attributeMappingFromKeyPath:nil toKeyPath:#"errorMessage"]];
// Add mapping as response descriptor
RKResponseDescriptor *errorDescriptor =
[RKResponseDescriptor responseDescriptorWithMapping:errorMapping
method:RKRequestMethodGET
pathPattern:nil
keyPath:#"message" // Edit the keyPath to the value of your JSON (e.g. errorCode)
statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassClientError)];
[RKObjectManager.sharedManager addResponseDescriptor:errorDescriptor];
To get the error message when a failure occurs, you simply get the message object. When using a block to get objects, you can use the userInfo dictionary from the given NSError.
RKErrorMessage *errorMessage = [[error.userInfo objectForKey:RKObjectMapperErrorObjectsKey] firstObject];
NSLog(#"Error: %#", errorMessage);
Now you can simplify your object model a bit and concentrate on mapping the BusinessObjectModel. When mapping the object using the dictionary, you need to check of your local attributes matches the value in your JSON.
RKObjectMapping *responseMapping = [RKObjectMapping mappingForClass:[BusinessObjectModel class]];
[responseMapping addAttributeMappingsFromDictionary:#
{
#"value_from_remote_json": #"value_in_local_object", // e.g. #"id" : #"business_id"
...
}];
return responseMapping;
You don't need to use a RKRelationshipMapping any more. Reconfigure your objects/mappings and try again. The logging will show you the provided mapping and if the mapping operations are working. Last bit not least make sure that the mapping is in memory when using it by throwing an NSAssert error.
RKObjectMapping *bMapping = [BusinessObjectModel getMapping];
NSAssert(bMapping, #"bMapping mapping must not be nil");
Edit
To map values without a keyPath (like the "errorCode" field) additionally to the mapping of your objects, you'll need to provide an object with an according mapping. Taking the example from the documentation you'll end with something like:
// Init object
#interface RKErrorCode : NSObject
#property (nonatomic) NSNumber *errorCode;
#end
// Init mapping
RKObjectMapping *codeMapping = [RKObjectMapping mappingForClass:[RKErrorCode class]];
[codeMapping addPropertyMapping:[RKAttributeMapping attributeMappingFromKeyPath:nil toKeyPath:#"errorCode"]];
// Add response descriptor for request
RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:codeMapping method:RKRequestMethodAny pathPattern:nil keyPath:#"errorCode" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[[RKObjectManager sharedManager] addResponseDescriptor:responseDescriptor];

Answer 2

Your response descriptor shouldn't have keyPath:#"bList", it should be set to nil as you don't want to drill in.
It also shouldn't use ResponseMapping based on the structure of your mappings, it should use the other mapping.
Your mapping is also wrong here:
#{
#"business_id": #"business_id",
#"business_name": #"business_name",
}];
It should be:
#{
#"id": #"business_id",
#"name": #"business_name",
}];
Because this specifies the JSON names and the core data names.
To fix your new issues, put this back:
[buslstMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:#"bList" toKeyPath:#"bList"
And this:
RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:buslstMapping method:RKRequestMethodAny pathPattern:nil keyPath:nil statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];

Answer 3

Found the solution and it looks something like this:
RKObjectMapping *bModelMapping = [RKObjectMapping mappingForClass:[business class]];
[bModelMapping addAttributeMappingsFromDictionary:#{
#"id": #"business_id",
#"name": #"business_name",
}];
RKObjectMapping *buslstMapping = [RKObjectMapping mappingForClass:[bModel class]];
[buslstMapping addAttributeMappingsFromDictionary:#{#"errorCode": #"errorCode"}];
// Define the relationship mapping
[buslstMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:#"bList"
toKeyPath:#"bList" bModelMapping]];
return buslstMapping;
Also Change the following:
#property (nonatomic, copy) NSMutableArray *bList;
to
#property (nonatomic, retain) NSArray *bList;
This gives me a bModel object with an error code value and a bList which is an array of business which can then be cast to a business by doing the following Business *business = [bModel.blist firstObject];