RestKit two consecutive enqueueBatchOfObjectRequestOperations not directly mapped to core data

Question

I'm using RestKit 0.20.2 in combination with MagicalRecord (important for any eventual context problems that you can think of).

My app is a saving tickets(entity) with items(entity) and each item has a tax(entity). My use case is this : I need to sync core data with my webserver when the ipad reconnects to the internet after a long period of time beeing unable to send the data (for whatever reason)

My problem is to be able to sync a lot of objects (it can go from 100 to a 1000 to even more), to be able to post a lot of objects without timeouts I set the restkit concurrency :

[RKObjectManager sharedManager].operationQueue.maxConcurrentOperationCount = 3;

Now this is working absolutely fine. But my problem is that i have alot of redundant entities that syncs with every item. For instance each item has a tax, but i only have two taxes in my model that need to be synced with the web service and then sent as a relationship with the item (i only put the id of the tax). So to circumvent that problem for each postItem i check if the related Tax has an ID, if yes, then i can parse the item directly with the tax relationship in it, if not, i need to sync the tax first then the item with the returned taxID.

The work around is working as expected too. But again there is a problem, because between each postItem RestKit isn't saving the newly TaxID between two requests, so instead of sending it once, it sends it every time it encounters it inside an item and when all the operations are done it saves the newly created taxIDs

To improve that I digged a bit in restkit and found

- (void)enqueueBatchOfObjectRequestOperations:(NSArray *)operations
                                 progress:(void (^)(NSUInteger numberOfFinishedOperations, NSUInteger totalNumberOfOperations))progress
                               completion:(void (^)(NSArray *operations))completion

So now i'm building RKManagedObjectRequestOperations for my tax entities and batch them. Then i sync the items. It's more efficient, and i don't need to set a dependency between operations (because i need them to be executed in a certain order, tax then items then the whole ticket.)

PROBLEM Between the two enqueueBatchOperations, RestKit doesn't map the result of the first batch immediately, even if i explicitly call

[[RKManagedObjectStore defaultStore].mainQueueManagedObjectContext saveToPersistentStore:&error]

It isn't mapped because after the first batch of taxes, i send all the items, and i can see that the taxID's aren't set, but after all the batches are done, i can clearly see them mapped correctly in my core data file. So I thought it was a context issue, but when i digg into RestKit and more specifically in

appropriateObjectRequestOperationWithObject:(id)object
                                           method:(RKRequestMethod)method
                                             path:(NSString *)path
                                       parameters:(NSDictionary *)parameters

I can see line 580 :

NSManagedObjectContext *managedObjectContext = [object respondsToSelector:@selector(managedObjectContext)] ? [object managedObjectContext] : self.managedObjectStore.mainQueueManagedObjectContext;

That sets the mainQueueContext (and not the object context) for the operations (i've checked with breakpoints), so calling save or saveToPersistentStore should propagate the changes from child contexts to the mainQueue and... it's where i've lost hope and turned to stackoverflow ;)

nebuto nebuto · Accepted Answer · 2013-06-20T13:04:15

As it usually happens i found the solution after posting on SO :)

The problem was that the RKManagedObjectRequestOperations where all created before restkit actually sent the information. So the context was the same for all the requests (as mentioned in the appropriateObjectRequestOperationWithObject method, and the changes weren't propagated because the context reference was the "old" reference.

To have the information on the next requests i just build the RKManagedObjectRequestOperations in the enqueueBatchOfOperations completion block, and now all is working fine with the newly created taxID ;)

RestKit two consecutive enqueueBatchOfObjectRequestOperations not directly mapped to core data

1 Answers