Question

I use RESTKit successfully to access a Web service. But I have problems to map server errors (like 404, 403…) to RESTKit’s standard RKErrorMessage class. Let’s say I get the following JSON response from my service together with a 403 status code:

{"errors":{"message":"Some error message"}}

In my iOS application I try to map the errors with the help of:

RKObjectMapping *errorMapping = [RKObjectMapping mappingForClass:[RKErrorMessage class
[errorMapping addPropertyMapping:[RKAttributeMapping
   attributeMappingFromKeyPath:@"message" toKeyPath:@"message"]];

statusCodes4xx = RKStatusCodeIndexSetForClass(RKStatusCodeClassClientError);

errorDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:notecardMapping 
                     pathPattern:nil keyPath:@"errors" statusCodes:statusCodes4xx];

But all I get is an error from RESTKit:

Failed mapping operation: No mappable values found for any of the attributes or relationship mappings

Where is my fault? Is it just a wrong path in the descriptor for example?

Answer 1

You seem to be using notecardMapping instead of errorMapping in your response descriptor. Try this:

RKObjectMapping *errorMapping = [RKObjectMapping mappingForClass:[RKErrorMessage class]];

[errorMapping addPropertyMapping:[RKAttributeMapping attributeMappingFromKeyPath:nil toKeyPath:@"errorMessage"]];

RKResponseDescriptor *errorDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:errorMapping
                                                                                pathPattern:nil
                                                                                    keyPath:@"errors.message"
                                                                                statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassClientError)];

[manager addResponseDescriptorsFromArray:@[errorDescriptor]];