RestKit not deleting orphaned objects from local store

Question

Hi i have updated RestKit from 0.10.2 to 0.20.3. After updating now when objects are missing from web service, RestKit not deleting them from local storage. I know it is supported in RestKit 0.20.x, but i am not being able to configure it. I followed the example given here. http://restkit.org/api/latest/Classes/RKManagedObjectRequestOperation.html#overview

I also followed similar questions on Stackoverflow. But there is no accepted answer yet.

Here is my Json

{
    "status": "Success",
    "member_info": [
        {
            "family_id": "1",
            "user_id": "1"
        },
        {
            "family_id": "2",
            "user_id": "1"
        },
        {
            "family_id": "3",
            "user_id": "1"
        }
    ]
}

Which returns all Family members for a particular user. Above Json is for user_id = 1. Now i want if request is sent for user_id = 2, then all the previous 3 objects should be deleted from local storage, as they are now missing from Json. Here is the new Json for user_id = 2

{
    "status": "Success",
    "member_info": [
        {
            "family_id": "4",
            "user_id": "2"
        },
        {
            "family_id": "5",
            "user_id": "2"
        }        
    ]
}

This is how i am creating mapping.

[objectManager addResponseDescriptorsFromArray:@[                                                                                                                  
                                                     [RKResponseDescriptor responseDescriptorWithMapping:[self connectionsMapping]
                                                                                                  method:RKRequestMethodPOST
                                                                                             pathPattern:@"familylist"
                                                                                                 keyPath:@"member_info" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)]];



[objectManager addFetchRequestBlock:^NSFetchRequest *(NSURL *URL) {
        RKPathMatcher *pathMatcher = [RKPathMatcher pathMatcherWithPattern:@"familylist"];
        NSDictionary *argsDict = nil;
        BOOL match = [pathMatcher matchesPath:[URL relativePath] tokenizeQueryStrings:NO parsedArguments:&argsDict];
        if (match) {
            NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"DBConnections"];
            NSPredicate *predicate = [NSPredicate predicateWithFormat:@"user_id == %@", [DBUser currentUser].user_id];
            fetchRequest.predicate = predicate;
            fetchRequest.sortDescriptors = @[ [NSSortDescriptor sortDescriptorWithKey:@"first_name" ascending:YES] ];
            return fetchRequest;
        }

        return nil;
    }];


- (RKEntityMapping *)connectionsMapping {   
    RKEntityMapping *connectionsMapping = [RKEntityMapping mappingForEntityForName:@"DBConnections" inManagedObjectStore:objectManager.managedObjectStore];
    connectionsMapping.setDefaultValueForMissingAttributes = NO;
    connectionsMapping.identificationAttributes = @[@"family_id"];
    [connectionsMapping addAttributeMappingsFromDictionary:@{
                                                             @"family_id": @"family_id",
                                                             @"user_id": @"user_id",
                                                             }];

    return connectionsMapping;
}

In predicate i am using [DBUser currentUser].user_id, which returns the current logged in user_id. And here is i am calling the web service

[[RKObjectManager sharedManager] postObject:nil path:@"familylist" parameters:params
                                            success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
NSLog(@"Objects are %@", mappingResult.array);
}];

I am using postObject instead of getObjectsAtPath, because server is expecting POST request method. Am i doing wrong? or need to do something else for deleting orphan objects. Any help is appreciated.

Answer 1

Finally solved the problem by debugging RestKit step by step and found this code in RKManagedObjectRequestOperation.m

if (! [[self.HTTPRequestOperation.request.HTTPMethod uppercaseString] isEqualToString:@"GET"]) {
        RKLogDebug(@"Skipping deletion of orphaned objects: only performed for GET requests.");
        return YES;
    }

Oh! RestKit doesn't delete orphan objects when the request method is POST. I changed the web services the accept GET request too and it worked perfectly. Secondly i was using predicate

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"user_id == %@", [DBUser currentUser].user_id];

It was wrong, to delete all objects except current user, i had to append NOT operator, like this

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"user_id != %@", [DBUser currentUser].user_id];

So predicate doesn't mean what you want, but it is what you don't want.