CoreData with RestKit - ios

Question

Try to implement usage of CoreData with RestKit.
Problem - got message I restkit.core_data:RKInMemoryManagedObjectCache.m:94 Caching instances of Entity 'ItemRK' by attributes 'itemID' and crash. Try to add Exception on errors- cant catch it.
Check mapping - OK;
Check DBModel - OK; empty DB created successfully
I cant understand what was done wrong and where, so I put here main parts of code (sorry for long explanation).
What was done:
I try to organize my code like proposed here.
So i create RKBaseObjectManager for using RestKit
#implementation RKBaseObjectManager
#pragma mark - Public
+ (instancetype)sharedManager
{
RKBaseObjectManager *sharedManager = [self managerWithBaseURL:[NSURL URLWithString:kBaseApiUrl]];
sharedManager.requestSerializationMIMEType = RKMIMETypeJSON;
[sharedManager setupRequestDescriptor];
[sharedManager setupResponseDescriptor];
[sharedManager setupCoreDataWithRKObjectManager:sharedManager];
return sharedManager;
}
- (void)setupRequestDescriptor { }
- (void)setupResponseDescriptor { }
#pragma mark - Private
- (void)setupCoreDataWithRKObjectManager:(RKObjectManager *)manager
{
NSManagedObjectModel *managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];
manager.managedObjectStore = managedObjectStore;
[managedObjectStore createPersistentStoreCoordinator];
NSString *dbName = [NSString stringWithFormat:#"%#.sqlite", kDataBaseName];
NSString *storePath = [RKApplicationDataDirectory() stringByAppendingPathComponent:dbName];
NSError *error;
NSPersistentStore *persistentStore = [managedObjectStore
addSQLitePersistentStoreAtPath:storePath
fromSeedDatabaseAtPath:nil
withConfiguration:nil
options:#{NSMigratePersistentStoresAutomaticallyOption : #YES, NSInferMappingModelAutomaticallyOption: #YES}
error:&error];
NSAssert(persistentStore, #"Failed to add persistent Store with error - %#", error.localizedDescription);
[managedObjectStore createManagedObjectContexts];
managedObjectStore.managedObjectCache = [[RKInMemoryManagedObjectCache alloc] initWithManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
}
#end
Then for each entity create inherited class with singleton - ItemManager
#implementation ItemManager
#pragma mark - Singleton
+ (instancetype)sharedManager
{
static ItemManager *sharedManager = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^ {
sharedManager = [super sharedManager];
});
return sharedManager;
}
#pragma mark - Public
- (void)loadItemWithId:(NSInteger)itemId success:(ObjectSuccess)success failure:(ObjectFailure)failure
{
NSDictionary *parameters = #{ #"item_id" : #(itemId) };
[self getObjectsAtPath:kItemsDetailsPathPattern parameters:parameters success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
if (success) {
success(mappingResult.array);
}
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
if (failure) {
failure (operation, error);
}
}];
}
#pragma mark - Private
- (void)setupResponseDescriptor
{
[super setupResponseDescriptor];
NSIndexSet *statusCode = RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful);
RKResponseDescriptor *itemDescriptor = [RKResponseDescriptor
responseDescriptorWithMapping:[MappingProvider mappingForItemRKEntity]
method:RKRequestMethodGET
pathPattern:kItemsDetailsPathPattern
keyPath:nil
statusCodes:statusCode];
[self addResponseDescriptor:itemDescriptor];
}
#end
For mapping I add next class - MappingProvider
#implementation MappingProvider
#pragma mark - EntityMapping
+ (RKEntityMapping *)mappingForItemRKEntity
{
RKEntityMapping *itemEntityMapping = [RKEntityMapping mappingForEntityForName:MPItemEntityName inManagedObjectStore:[RKBaseObjectManager sharedManager].managedObjectStore];
itemEntityMapping.identificationAttributes = #[#"itemID"];
[itemEntityMapping addAttributeMappingsFromDictionary:[self mappingDictionaryForItem]];
return itemEntityMapping;
}
+ (RKObjectMapping *)mappingForItemRK
{
RKObjectMapping *itemMapping = [RKObjectMapping mappingForClass:[ItemRK class]];
[itemMapping addAttributeMappingsFromDictionary:[self mappingDictionaryForItem]];
return itemMapping;
}
#pragma mark - Private
+ (NSDictionary *)mappingDictionaryForItem
{
NSDictionary *dictionary = #{
#"item_id" : #"itemID",
#"name" : #"name",
#"description" : #"itemDescription",
#"type" : #"type",
#"level" : #"level",
#"rarity" : #"rarity",
#"vendor_value" : #"vendorValue",
#"icon_file_id" : #"iconFileId",
#"icon_file_signature" : #"iconFileSignature",
#"default_skin" : #"defaultScin"
};
return dictionary;
}
And when I want to get object -
[[ItemManager sharedManager] loadItemWithId:28445 success:^(NSArray *mappingResult) {
ItemRK *result = (ItemRK *)[mappingResult firstObject];
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
NSLog(#"Fail to load - %#", error.localizedDescription);
}];
Test entity class (autoGenerated)
#interface ItemRK : NSManagedObject
#property (nonatomic, retain) NSNumber * defaultScin;
#property (nonatomic, retain) NSNumber * flags;
#property (nonatomic, retain) NSData * gameTypes;
#property (nonatomic, retain) NSNumber * iconFileId;
#property (nonatomic, retain) NSString * iconFileSignature;
#property (nonatomic, retain) NSString * itemDescription;
#property (nonatomic, retain) NSNumber * itemID;
#property (nonatomic, retain) NSNumber * level;
#property (nonatomic, retain) NSString * name;
#property (nonatomic, retain) NSString * rarity;
#property (nonatomic, retain) NSData * restrictions;
#property (nonatomic, retain) NSString * type;
#property (nonatomic, retain) NSNumber * vendorValue;
#property (nonatomic, retain) WeaponRK *weapon;
#end
So the problem is as I wrote at beggining - something with core_data:RKInMemoryManagedObjectCache. Also try to found similar problems:
To many unique keys added - not the reason - I use only one itemEntityMapping.identificationAttributes = #[#"itemID"];
To many request - not the reason - only one request;
API for my example - https://api.guildwars2.com/v1/item_details.json?item_id=28445 - checked with Postman - OK.
So think I was wrong somewhere in mapping and combining it to CoreData - but cant find where.
Question - where i make mistake? Why i cant combine RestKit and CoreData?

Answer 1

Finally found the reason -
When I create ItemManager I also automatically try to add response descriptor (with this method setupResponseDescriptor), last use mapping, and mapping use 'BaseObjectManager' as it managedObjectStore the is a parent for ItemManager. So during creating ItemManager I create infinity cycle - as result program crashed.
Solution - I create response descriptor in class where I call ItemManager like
[[ItemManager sharedManager] addResponseDescriptor:[ResponseDescriptorProvider itemResponseDescriptor]];
[[ItemManager sharedManager] loadItemWithId:28450 success:^(NSArray *result) {
NSArray *arout = result;
NSLog(#"Result: Item - %# and nested Weapon - %#", (ItemRK *)[arout firstObject], ((WeaponRK *)((ItemRK *)[arout firstObject]).weapon).type );
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
NSLog(#"Error response': %#", error);
}];
Also i moved out response descriptor from manager to separate class - ResponseDescriptorProvider
+ (RKResponseDescriptor *)itemResponseDescriptor
{
RKResponseDescriptor *responseDescriptor =
[RKResponseDescriptor responseDescriptorWithMapping:[MappingProvider mappingForItemRKEntity]
method:RKRequestMethodGET
pathPattern:kItemsDetailsPathPattern
keyPath:nil
statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
return responseDescriptor;
}
The rest leave the same.
Thanks all for help.