Workaround for Managed Object Relationship Sequencing Problems

gistfile1.m

// Add `NSMutableDictionary* _managedObjectMappingsAndObjects;` to ivars and dealloc
- (void)objectMapper:(RKObjectMapper*)objectMapper didMapFromObject:(id)sourceObject toObject:(id)destinationObject atKeyPath:(NSString*)keyPath usingMapping:(RKObjectMapping*)objectMapping {
    if ([objectMapping isKindOfClass:[RKManagedObjectMapping class]]) {
        if (nil == _managedObjectMappingsAndObjects) {
            _managedObjectMappingsAndObjects = [NSMutableDictionary new];
        }
        if (nil == [_managedObjectMappingsAndObjects objectForKey:objectMapping]) {
            [_managedObjectMappingsAndObjects setObject:[NSMutableArray arrayWithObject:destinationObject] forKey:objectMapping];
        } else {
            [[_managedObjectMappingsAndObjects objectForKey:objectMapping] addObject:destinationObject];
        }
    }    
}

- (void)objectMapperDidFinishMapping:(RKObjectMapper*)objectMapper {
    for (RKManagedObjectMapping* objectMapping in _managedObjectMappingsAndObjects) {
        for (NSManagedObject* object in [_managedObjectMappingsAndObjects objectForKey:objectMapping]) {
            NSDictionary* relationshipsAndPrimaryKeyAttributes = [objectMapping relationshipsAndPrimaryKeyAttributes];
            for (NSString* relationshipName in relationshipsAndPrimaryKeyAttributes) {
                NSString* primaryKeyAttribute = [relationshipsAndPrimaryKeyAttributes objectForKey:relationshipName];
                RKObjectRelationshipMapping* relationshipMapping = [self.objectMapping mappingForKeyPath:relationshipName];
                id<RKObjectMappingDefinition> mapping = relationshipMapping.mapping;
                if (! [mapping isKindOfClass:[RKObjectMapping class]]) {
                    RKLogWarning(@"Can only connect relationships for RKObjectMapping relationships. Found %@: Skipping...", NSStringFromClass([mapping class]));
                    continue;
                }
                RKObjectMapping* objectMapping = (RKObjectMapping*)mapping;
                NSAssert(relationshipMapping, @"Unable to find relationship mapping '%@' to connect by primaryKey", relationshipName);
                NSAssert([relationshipMapping isKindOfClass:[RKObjectRelationshipMapping class]], @"Expected mapping for %@ to be a relationship mapping", relationshipName);
                NSAssert([relationshipMapping.mapping isKindOfClass:[RKManagedObjectMapping class]], @"Can only connect RKManagedObjectMapping relationships");
                NSString* primaryKeyAttributeOfRelatedObject = [(RKManagedObjectMapping*)objectMapping primaryKeyAttribute];
                NSAssert(primaryKeyAttributeOfRelatedObject, @"Cannot connect relationship: mapping for %@ has no primary key attribute specified", NSStringFromClass(objectMapping.objectClass));
                id valueOfLocalPrimaryKeyAttribute = [object valueForKey:primaryKeyAttribute];
                if (valueOfLocalPrimaryKeyAttribute) {
                    id relatedObject = [objectMapping.objectClass findFirstByAttribute:primaryKeyAttributeOfRelatedObject withValue:valueOfLocalPrimaryKeyAttribute];
                    [object setValue:relatedObject forKey:relationshipName];
                }
            }
        }        
    }
}

I think there's an error in this code, what's destinationObject on line 25/28?

Buzali -

Thanks. I have updated it to reference self.targetObject instead.

Added to RestKit wiki @ https://github.com/RestKit/RestKit/wiki/Sequencing-issue-with-core-data-relationships

I can't get it to work.
I think in line 10 and 13, it should be objectMapping instead of self.objectMapping. Also self.targetObject is always nil. Is targetObject supposed to be within the ObjectLoader?