How to Post to database via RestKit 0.20 - ios

Question

I am trying to POST to an API using restkit.
When I press save post- I get an error showing an empty post and alert saying:
Expected status code in (200-299), got 422" UserInfo=0xb83ca20 {NSLocalizedRecoverySuggestion={"body":["can't be blank"]},
The post is displayed in the tableView but the text I entered doesn't make it to the database.
Any ideas why this might be? The usual problems I've seen are because people are missing parsing the data to json or because they lack a responseDescriptor - but I have this and I'm not getting the json error. It's just not retaining the text I enter.
Why is this?
My savePost method is like this
RKManagedObjectStore *objectStore = [[RKObjectManager sharedManager] managedObjectStore];
Post *post = [NSEntityDescription insertNewObjectForEntityForName:#"Post" inManagedObjectContext:objectStore.mainQueueManagedObjectContext];
[post setBody:self.postTextField.text];
[objectStore.mainQueueManagedObjectContext save:nil];
RKObjectManager *manager = [RKObjectManager sharedManager]; [manager postObject:self path:#"/posts.json" parameters:nil success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
NSLog(#"Success saving post");
// [MUser setCurrentUser:self];
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
NSLog(#"Failure saving post: %#", error.localizedDescription);
}];
And in my appDelegate I have this setup:
NSError *error = nil;
NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:#"Markofresh" ofType:#"momd"]];
// NOTE: Due to an iOS 5 bug, the managed object model returned is immutable.
NSManagedObjectModel *managedObjectModel = [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL] mutableCopy];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];
// Initialize the Core Data stack
[managedObjectStore createPersistentStoreCoordinator];
NSPersistentStore __unused *persistentStore = [managedObjectStore addInMemoryPersistentStore:&error];
NSAssert(persistentStore, #"Failed to add persistent store: %#", error);
[managedObjectStore createManagedObjectContexts];
// Configure a managed object cache to ensure we do not create duplicate objects
managedObjectStore.managedObjectCache = [[RKInMemoryManagedObjectCache alloc] initWithManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
// Set the default store shared instance
[RKManagedObjectStore setDefaultStore:managedObjectStore];
// Configure the object manager
RKObjectManager *objectManager = [RKObjectManager managerWithBaseURL:[NSURL URLWithString:#"https://fierce.herokuapp.com"]];
objectManager.managedObjectStore = managedObjectStore;
[objectManager setRequestSerializationMIMEType:#"application/json"];
[objectManager setAcceptHeaderWithMIMEType:#"application/json"];
[RKObjectManager setSharedManager:objectManager];
//setup Post Entity map
RKEntityMapping *entityMapping = [RKEntityMapping mappingForEntityForName:#"Post" inManagedObjectStore:managedObjectStore];
[entityMapping addAttributeMappingsFromDictionary:#{
#"id": #"postID",
#"url": #"jsonURL",
#"body": #"body",
#"created_at": #"createdAt"}];
entityMapping.identificationAttributes = #[ #"postID" ];
[RKObjectManager sharedManager].requestSerializationMIMEType = RKMIMETypeJSON;
RKResponseDescriptor *responseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:entityMapping pathPattern:#"/posts.json" keyPath:nil statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[objectManager addResponseDescriptor:responseDescriptor];
RKRequestDescriptor *requestDescriptor = [RKRequestDescriptor requestDescriptorWithMapping:[entityMapping inverseMapping] objectClass:[Post class] rootKeyPath:#"/posts.json"];
[objectManager addRequestDescriptor:requestDescriptor];
I have seen other people get hung up on this and wonder if maybe AFNetworking might be a better choice for this kind of simple method- and there's more documentation on it as well.
I know what I'm trying to do is simple and I don't get what is causing the empty post. Any help would be greatly appreciated.

Answer 1

Should you be doing:
[manager postObject:post path:#"/posts.json" parameters:nil ...
So your issue is simply a typo?
Try turning on mapping trace logging so you can see what's happening:
RKLogConfigureByName("RestKit/ObjectMapping", RKLogLevelTrace);
And think about something like the Charles Proxy to show you exactly what's hitting the wire.