How to map JSON Arrays in RestKit

Question

I have some troubles mapping a JSON Array to RestKit. This is what the JSON File looks like:

{"issuelist":[
    {
        "issue":[
            {
                "id":1,
                "beschreibung":"",
                "name":"Test1"
            },
            {
                "id":2,
                "beschreibung":"",
                "name":"Test2"
            }
        ]
    }
]}

I am interested in the "issue"s array. This is my mapping for a single issue:

RKObjectMapping *objectMapping = [RKObjectMapping mappingForClass:[self class] usingBlock:^(RKObjectMapping *mapping) {
        [mapping mapAttributes:@"name", @"beschreibung", nil];
        [mapping mapKeyPathsToAttributes:
                @"id", @"identifier",
                nil];
    }];

And here is how I setup my ObjectMapping

RKObjectMappingProvider *omp = [RKObjectManager sharedManager].mappingProvider;

RKObjectMapping *issueMapping = [Issue mapping];
[omp addObjectMapping:issueMapping];

[omp setObjectMapping:issueMapping forKeyPath:@"issuelist.issue"];

Unfortunately this doesn't work. I get an log output like this:

    T restkit.object_mapping:RKObjectMappingOperation.m:152 Found transformable value at keyPath 'name'. Transforming from type '__NSArrayI' to 'NSString'
    W restkit.object_mapping:RKObjectMappingOperation.m:232 Failed transformation of value at keyPath 'name'. No strategy for transforming from '__NSArrayI' to 'NSString'
    T restkit.object_mapping:RKObjectMappingOperation.m:339 Skipped mapping of attribute value from keyPath 'name to keyPath 'name' -- value is unchanged ((null))
    T restkit.object_mapping:RKObjectMappingOperation.m:322 Mapping attribute value keyPath 'beschreibung' to 'beschreibung'
    T restkit.object_mapping:RKObjectMappingOperation.m:152 Found transformable value at keyPath 'beschreibung'. Transforming from type '__NSArrayI' to 'NSString'
    W restkit.object_mapping:RKObjectMappingOperation.m:232 Failed transformation of value at keyPath 'beschreibung'. No strategy for transforming from '__NSArrayI' to 'NSString'
    T restkit.object_mapping:RKObjectMappingOperation.m:339 Skipped mapping of attribute value from keyPath 'beschreibung to keyPath 'beschreibung' -- value is unchanged ((null))
    T restkit.object_mapping:RKObjectMappingOperation.m:322 Mapping attribute value keyPath 'id' to 'identifier'
    T restkit.object_mapping:RKObjectMappingOperation.m:152 Found transformable value at keyPath 'id'. Transforming from type '__NSArrayI' to 'NSString'
    W restkit.object_mapping:RKObjectMappingOperation.m:232 Failed transformation of value at keyPath 'id'. No strategy for transforming from '__NSArrayI' to 'NSString'
    T restkit.object_mapping:RKObjectMappingOperation.m:339 Skipped mapping of attribute value from keyPath 'id to keyPath 'identifier' -- value is unchanged ((null))
    D restkit.object_mapping:RKObjectMappingOperation.m:624 Finished mapping operation successfully...

It seems as if RestKit is trying to map the whole arry in one Issue instead of creating an array of Issues. How do I need to change my mapping to correct this?

Thanks for your help!

Answer 1

Try this:

RKObjectMapping* issueMapping = [RKObjectMapping mappingForClass: [Issue class] usingBlock:^(RKObjectMapping *mapping) {
    [mapping mapAttributes:@"name", @"beschreibung", nil];
    [mapping mapKeyPathsToAttributes:
     @"id", @"identifier",
     nil];
}];
issueMapping.rootKeyPath = @"issue";
[omp setObjectMaping: issueMapping forKeyPath: @"issuelist"];

This says, when issuelist keypath is encountered use the issueMapping. And then it says for every root issue, create an Issue object.