using RestKit to serialize an object with a subobject [POSTing] - ios

Question

I have the following objects setup:
RKObjectMapping* geoPointMapping = [RKObjectMapping mappingForClass:[CRGeoPoint class]];
geoPointMapping.setDefaultValueForMissingAttributes = YES;
[geoPointMapping mapKeyPathsToAttributes:
#"longitude", #"longitude",
#"latitude", #"latitude",
nil];
[objectManager.mappingProvider registerMapping:geoPointMapping withRootKeyPath:#"geometry"];
RKObjectMapping* criteriaMapping = [RKObjectMapping mappingForClass:[CRCriteria class]];
criteriaMapping.setDefaultValueForMissingAttributes = YES;
[criteriaMapping mapKeyPathsToAttributes:
#"type", #"type",
#"geometry", #"geometry",
#"fromDate", #"fromDate",
#"toDate", #"toDate",
#"radius", #"radius",
nil];
[objectManager.mappingProvider registerMapping:criteriaMapping withRootKeyPath:#"criteria"];
But when I try and send the query (with a geometry object). I keep
getting this error:
error received Error Domain=JKErrorDomain Code=-1 "Unable to serialize
object class CRGeoPoint."

Answer 1

Inbound and outbound mapping information is handled separately by RKObjectMappingProvider. You've configured the inbound mapping in that code (downloading the data from your server). But--as pointed out by Shane Zatezalo on the RestKit group--you also need to add a serialization mapping for RestKit to know how to turn your objects into JSON (or whatever other serialization format you might be using).
Check out the Object Mapping tutorial's section on Object Serialization. And take a look at the source for the mapping provider to reassure yourself that these things are separate.

Answer 2

Solution by OP.
The solution was two-fold. First I had to specify the inverse mapping as Sixten pointed out below, second I had to specify the mapping to use for the CRGeoPoint class on the CRCriteria object. Code below:
RKObjectMapping* geoPointMapping = [RKObjectMapping mappingForClass:[CRGeoPoint class]];
geoPointMapping.setDefaultValueForMissingAttributes = YES;
[objectManager.mappingProvider registerMapping:geoPointMapping withRootKeyPath:#"geometry"];
// Build a serialization mapping by inverting our object mapping. Includes attributes and relationships
RKObjectMapping* geoPointSerializationMapping = [geoPointMapping inverseMapping];
// You can customize the mapping here as necessary -- adding/removing mappings
[[RKObjectManager sharedManager].mappingProvider setSerializationMapping:geoPointSerializationMapping forClass:[CRGeoPoint class]];
RKObjectMapping* criteriaMapping = [RKObjectMapping mappingForClass:[CRCriteria class]];
criteriaMapping.setDefaultValueForMissingAttributes = YES;
[criteriaMapping mapKeyPathsToAttributes:
#"type", #"type",
#"fromDate", #"fromDate",
#"toDate", #"toDate",
#"radius", #"radius",
nil];
[criteriaMapping mapKeyPath:#"geometry" toRelationship:#"geometry" withMapping:geoPointMapping];
[objectManager.mappingProvider registerMapping:criteriaMapping withRootKeyPath:#"criteria"];
// Build a serialization mapping by inverting our object mapping. Includes attributes and relationships
RKObjectMapping* criteriaSerializationMapping = [criteriaMapping inverseMapping];
// You can customize the mapping here as necessary -- adding/removing mappings
[[RKObjectManager sharedManager].mappingProvider setSerializationMapping:criteriaSerializationMapping forClass:[CRCriteria class]];