Getting "this class is not key value coding-compliant for the key id." when requesting RestKit loadObjectsAtResourcePath

Question

I'm trying to deserialise JSON data into my iPhone application using RestKit's RKObjectManager.

My current issue is the app crashes with a :

*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<Course 0x6e71b10> valueForUndefinedKey:]: this class is not key value coding-compliant for the key id.'

when I call:

[manager loadObjectsAtResourcePath:@"/courses" delegate:nil];

My domain class - Course.h looks like

#import <Foundation/Foundation.h>



@interface Course : NSObject  {

}

@property(nonatomic) NSInteger *id;

@property(nonatomic, retain) NSString *name;

-(id)initWithIdAndName: (NSInteger *)inId inName:(NSString *)inName;
@end

and the Course.m looks like

#import "Course.h"
#import "NSDictionary+RKAdditions.h"


@implementation Course {

}
@synthesize name = _name;
@synthesize id = _id;

- (id)initWithIdAndName:(NSInteger *)inId inName:(NSString *)inName {
    _name = inName;
    _id = inId;
    return self;

}

#pragma mark NSCoding Protocol


- (void)encodeWithCoder:(NSCoder *)encoder;
{
[encoder encodeInteger:[self id] forKey:@"id"];
[encoder encodeObject:[self name] forKey:@"name"];
}

- (id)initWithCoder:(NSCoder *)decoder;
{
if ( ![super init] )
    return nil;

[self setId:[decoder decodeIntForKey:@"id"]];
[self setName:[decoder decodeObjectForKey:@"name"]];


return self;
}

@end 

The Json data retrieved from the server is

{"courses":[{"id":1,"name":"course 1"},{"id":2,"name":"course 2"}]}

And the RKObjectManager is invoked using the following code:

RKObjectMapping* courseMapping = [RKObjectMapping mappingForClass:[Course class]];
[courseMapping mapKeyPath:@"id" toAttribute:@"id"];
[courseMapping mapKeyPath:@"name" toAttribute:@"name"];


RKObjectManager *manager = [RKObjectManager objectManagerWithBaseURL:@"http://firstbit/of/url"];

[manager.mappingProvider setMapping:courseMapping forKeyPath:@"courses"];
[manager loadObjectsAtResourcePath:@"/endpoint" delegate:nil];

Any ideas on this one?

Answer 1

It might help others, but I had this problem and the reason was that I was using NSInteger in my object definition. RestKit cannot map to NSInteger, only NSNumber.