iOS RestKit can not save local entity to database

Question

I am using RestKit 0.20 to parse JSON data and save to database. THere is a mapped entity SchoolClass, which is handled by RestKit and saves fine. I have another entity called MyClass, which stores the classes I have selected. This one is only local on the device.

Here is the code I create and save the MyClass entity

 NSManagedObjectContext *managedObjCtx = [RKManagedObjectStore defaultStore].mainQueueManagedObjectContext;
 MyClass* course = [managedObjCtx insertNewObjectForEntityForName:@"MyClass"];

 .. set the data for course here

 NSError *executeError = nil;
 if(![managedObjCtx save:&executeError]) {
      NSLog(@"Failed to save to data store");
 }

Here is the code that initialize the managed data store

  // Initialize managed object store
    NSManagedObjectModel *managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
    RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];
    objectManager.managedObjectStore = managedObjectStore;

   /**
     Complete Core Data stack initialization
     */
    [managedObjectStore createPersistentStoreCoordinator];
    NSString *storePath = [RKApplicationDataDirectory() stringByAppendingPathComponent:@"RKMainDb.sqlite"];
    NSString *seedPath = [[NSBundle mainBundle] pathForResource:@"RKSeedDatabase" ofType:@"sqlite"];
    NSError *error;
    NSPersistentStore *persistentStore = [managedObjectStore addSQLitePersistentStoreAtPath:storePath fromSeedDatabaseAtPath:seedPath withConfiguration:nil options:nil error:&error];
    NSAssert(persistentStore, @"Failed to add persistent store with error: %@", error);

    // Create the managed object contexts
    [managedObjectStore createManagedObjectContexts];

    // Configure a managed object cache to ensure we do not create duplicate objects
    managedObjectStore.managedObjectCache = [[RKInMemoryManagedObjectCache alloc] initWithManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];

It appears the save is successful and in the MyClasseTableViewController I could read the saved MyClass entries. However after I close the app and restart again. The MyClassTableViewController is empty, because the fetched results is empty. I opened the sqlite file using SQLiteBrowser and the MyClass table is empty. Looks like the MyClass entities are only saved in the cache but not in the persistent store. Do I need to call some API provided by RestKit to save it? I tried to read through the doc but could not find it. Please help.

Thi

Are you using nested managed object contexts? If so, you'll need to save the root context to get changes saved to the data store. – Burford

hi Tom, thanks for the input. I added some code to the question that shows how the store is created. I use the RKManagedObjectStore class to do that, and always get the managedObjectContext from it. Perhaps RestKit is using something nested. I will dig deeper follow your lead. Thanks. – Thi

Answer 1

Thanks for the lead by Tom, I found that RestKit has NSManagedObjectContext (RKAdditions), which has a method:

- (BOOL)saveToPersistentStore:(NSError **)error

Yes it does have logic to handle nested managed object context. Here is the new code that works, just one line change, but took a lot of time to find the right call :(

#import "NSManagedObjectContext+RKAdditions.h"
     NSManagedObjectContext *managedObjCtx = [RKManagedObjectStore defaultStore].mainQueueManagedObjectContext;
     MyClass* course = [managedObjCtx insertNewObjectForEntityForName:@"MyClass"];

     .. set the data for course here

     NSError *executeError = nil;
     if(![managedObjCtx saveToPersistentStore:&executeError]) {
          NSLog(@"Failed to save to data store");
     }

Thi

THANK YOU SO MUCH!!!! :( so much time spent searching everywhere for this!! Thank you thank you!!! – Cashbook

THANK YOU. been using the framework for a long time now but still forgotten this. lol – Protection