How to change JSON before mapping by RESTKIT - objective-c

Question

I am using RESTKIT to map the JSON returned from server.
The JSON result obtained from server is as follows
{"term":"Zh","results":{"users":[{"id":{"$oid":"4ebe59970a614e0019000055"},"term":"some text","score":1}]}
How can I convert the above JSON result to the below:
{"results":{"users":[{"uid":"4ebe59970a614e0019000055","text":"some text"}]}
Also, where can I do this so that the RESTKIT mapping will use the converted JSON instead of the initial one?
Below is the loader class that I am using to manage the JSON and mappings
-(void)getObjects
{
RKObjectManager *sharedManager = [RKObjectManager sharedManager];
[sharedManager loadObjectsAtResourcePath:self.resourcePath delegate:self];
}
- (void)request:(RKRequest*)request didLoadResponse:(RKResponse*)response {
NSLog(#"Loaded PAYLOAD successfully for %#, with response %#", self.resourcePath , [response bodyAsString] );
}
- (void)objectLoader:(RKObjectLoader*)objectLoader didLoadObjects:(NSArray*)objects
{
}
+ (void)setManagerAndMappings
{
RKObjectManager* manager = [RKObjectManager objectManagerWithBaseURL:SERVER_URL];
RKObjectMappingProvider* provider = [[RKObjectMappingProvider new] autorelease];
//User Object Mapping
RKObjectMapping* userMapping = [RKObjectMapping mappingForClass:[User class]];
[userMapping mapKeyPath:#"_id" toAttribute:#"uid"];
[userMapping mapAttributes:#"avatar_url",#"created_at",#"email",#"name",#"nickname",#"follower_count",#"following_count",#"answer_count",#"new_notification_count",#"new_questions_count",#"is_following",#"facebook_configured",#"twitter_configured",#"description",#"approved",#"type", nil];
[provider setMapping:userMapping forKeyPath:#"user"];
}

Answer 1

#Shocks answer is appealing, unfortunately it is valid a for version before 0.20.
Anyway, a similar solution is available for 0.20 too, using an implementation of RKSerialization:
#interface ORRKJsonSerialization : NSObject <RKSerialization>
#end
and implementing
#implementation ORRKJsonSerialization
+ (id)objectFromData:(NSData *)data error:(NSError **)error
{
id result = [NSJSONSerialization JSONObjectWithData:data options:0 error:error];
// change your data before mapping
return result;
}
+ (NSData *)dataFromObject:(id)object error:(NSError **)error
{
return [NSJSONSerialization dataWithJSONObject:object options:0 error:error];
}
#end
then during the setup:
[RKMIMETypeSerialization registerClass:[ORRKJsonSerialization class] forMIMEType:#"application/json"];
HTH

Answer 2

There is a willMapData: selector in the RKObkectLoaderDelegate that is invoked just after parsing has completed. The mappableData argumet is mutable, so i guess you can change the data just before the object mapping will take place.

Answer 3

use RKObjectRequestOperation.setWillMapDeserializedResponseBlock:.
In swift:
let request = RKObjectManager.sharedManager().requestWith...
let operation = RKObjectManager.sharedManager().managedObjectRequestOperationWithRequest(request, managedObjectContext: context, success: { operation, result in
// success
}, failure: { operation, error in
// failure
})
operation.setWillMapDeserializedResponseBlock { deserializedResponse -> AnyObject! in
// Here to transform response
return transformResponse(deserializedResponse)
}
RKObjectManager.sharedManager().enqueueObjectRequestOperation(operation)

Answer 4

For me the only solution is to modify the returned object at the server level.
If you can't,just map that returns the server.

Answer 5

You can register your own parser. I had to do this to modify and clean-up some JSON from a legacy system.
[[RKParserRegistry sharedRegistry] setParserClass:[MyJSONParser class]
forMIMEType:#"application/json"];
And then create your own:
#import <RestKit/RestKit.h>
#import <RestKit/RKJSONParserJSONKit.h>
#import <RestKit/JSONKit.h>
#import <RestKit/RKLog.h>
#interface EFJSONParser : RKJSONParserJSONKit
- (NSDictionary *)objectFromString:(NSString *)string error:(NSError **)error;
#end

Answer 6

It's very difficult to editing the response of JSOn. the better way is only to do changes in server side as said by #beber