Deserializing local NSString of JSON into objects via RestKit (no network download)

Question

Is it possible to deserialize an NSString of JSON into objects via RestKit? I checked the API list here and could not find something that would serve for this p

Answer 1

As of RestKit 0.20.0-pre2

NSString* JSONString = @"{ \"name\": \"The name\", \"number\": 12345}";
NSString* MIMEType = @"application/json";
NSError* error;
NSData *data = [JSONString dataUsingEncoding:NSUTF8StringEncoding];
id parsedData = [RKMIMETypeSerialization objectFromData:data MIMEType:MIMEType error:&error];
if (parsedData == nil && error) {
    // Parser error...
}

AppUser *appUser = [[AppUser alloc] init];

NSDictionary *mappingsDictionary = @{ @"someKeyPath": someMapping };
RKMapperOperation *mapper = [[RKMapperOperation alloc] initWithRepresentation:parsedData mappingsDictionary:mappingsDictionary];
mapper.targetObject = appUser;
NSError *mappingError = nil;
BOOL isMapped = [mapper execute:&mappingError];
if (isMapped && !mappingError) {
    // Yay! Mapping finished successfully
    NSLog(@"mapper: %@", [mapper representation]);
    NSLog(@"firstname is %@", appUser.firstName);
}

Answer 2

This works for Restkit 0.21.0:

NSString* jsonFilePath = [[NSBundle mainBundle] pathForResource:@"fileName"
                                                 ofType:@"json"];

NSString* JSONString = [NSString stringWithContentsOfFile:jsonFilePath
                                              encoding:NSUTF8StringEncoding
                                                 error:NULL];


NSError* error;
NSData *data = [JSONString dataUsingEncoding:NSUTF8StringEncoding];
id parsedData = [RKMIMETypeSerialization objectFromData:data MIMEType:RKMIMETypeJSON error:&error];
if (parsedData == nil && error) {
    // Parser error...
}

//_objectManager is RKObjectManager instance
NSMutableDictionary *mappingsDictionary = [[NSMutableDictionary alloc] init];
for (RKResponseDescriptor *descriptor in _objectManager.responseDescriptors) {
    [mappingsDictionary setObject:descriptor.mapping forKey:descriptor.keyPath];
}

RKMapperOperation *mapper = [[RKMapperOperation alloc] initWithRepresentation:parsedData mappingsDictionary:mappingsDictionary];
NSError *mappingError = nil;
BOOL isMapped = [mapper execute:&mappingError];
if (isMapped && !mappingError) {
    NSLog(@"result %@",[mapper mappingResult]);
}

Answer 3

Pretty "simple":

NSString *stringJSON;
...

RKJSONParserJSONKit *parser;
NSError *error= nil;
parser= [[[RKJSONParserJSONKit alloc] init] autorelease]; 
MyManagedObject *target;
target= [MyManagedObject object];

NSDictionary *objectAsDictionary;
RKObjectMapper* mapper;
objectAsDictionary= [parser objectFromString:stringJSON error:&error];
mapper = [RKObjectMapper mapperWithObject:objectAsDictionary 
                          mappingProvider:[RKObjectManager sharedManager].mappingProvider];
mapper.targetObject = target;
RKObjectMappingResult* result = [mapper performMapping];
NSLog(@"%@", [result asObject]);

Answer 4

Is this not what you're looking for? http://restkit.org/api/0.10.0/Classes/RKJSONParserJSONKit.html

Answer 5

A more iOS 5+ oriented answer:

NSString* JSONString = jsonString;
NSString* MIMEType = @"application/json";
NSError* error = nil;
id<RKParser> parser = [[RKParserRegistry sharedRegistry] parserForMIMEType:MIMEType];
id parsedData = [parser objectFromString:JSONString error:&error];
if (parsedData == nil && error) {
    NSLog(@"ERROR: JSON parsing error");
}

RKObjectMappingProvider* mappingProvider = [RKObjectManager sharedManager].mappingProvider;
RKObjectMapper* mapper = [RKObjectMapper mapperWithObject:parsedData mappingProvider:mappingProvider];
RKObjectMappingResult* result = [mapper performMapping];
if (result) {

    NSArray *resultArray = result.asCollection;

    MyObject *object = [resultArray lastObject];
    NSLog(@"My Object: %@", object);
}

Answer 6

For Restkit 0.22, You can use this code. This returns an RKMappingResult wherein you can enumerate the objects after mapping using the property .array.

- (RKMappingResult *)mapJSONStringWithString:(NSString *)jsonString
{
     RKMappingResult *result = nil;

     NSError* error;
     NSData *data = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
     id parsedData = [RKMIMETypeSerialization objectFromData:data MIMEType:RKMIMETypeJSON error:&error];
     if (parsedData == nil && error) {
        NSLog(@"json mapping error");
     }

     NSDictionary *mappingsDictionary = @{@"":[CustomMappingClass getMappingForUsers]};

     ObjectClass *obj = [ObjectClass new];
     RKMapperOperation *mapper = [[RKMapperOperation alloc] initWithRepresentation:parsedData mappingsDictionary:mappingsDictionary];
     NSError *mappingError = nil;
     mapper.targetObject = obj;
     BOOL isMapped = [mapper execute:&mappingError];
     if (isMapped && !mappingError) {
         result = [mapper mappingResult];
     }

    return result;
}