Deleting orphaned objects from relationship - ios

Question

I am attempting to use the addFetchRequestBlock method to remove orphaned objects from an API call I'm making. However, the objects I'd like it to remove are the objects from various relationships to the main object.
The outermost object is the Day object which has many FoodEntry objects.
API call to /nutrition/days/2014-07-14
RKManagedObjectRequestOperation *operation = [[RKObjectManager sharedManager] appropriateObjectRequestOperationWithObject:nil method:RKRequestMethodGET path:[NSString stringWithFormat:#"nutrition/days/%#", dateFormatted] parameters:nil];
[operation setDeletesOrphanedObjects:YES];
[operation setCompletionBlockWithSuccess:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
self.day = (Day *)mappingResult.firstObject;
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
failure([operation decodeErrors]);
}];
[RKObjectManager.sharedManager enqueueObjectRequestOperation:operation];
results in:
{
"day": {
"date": "2014-07-24",
"food_entries": [
{
"id": "53d14b973861330009de0300",
"consumed_on": "2014-07-24",
"food_id": 36394,
"serving_id": 34187,
"quantity": 1,
"name": "Waffle",
"brand": null,
"description": "1 cup slices",
"meal_type": "breakfast",
"calories": 25,
"carbohydrate": 6.68,
"protein": 0.48,
"fat": 0.04,
"saturated_fat": null,
"polyunsaturated_fat": null,
"monounsaturated_fat": null,
"trans_fat": null,
"cholesterol": 0,
"sodium": 9,
"potassium": 43,
"fiber": null,
"sugar": null
},
{
"id": "53d151c138313800099c0100",
"consumed_on": "2014-07-24",
"food_id": 38720,
"serving_id": 48329,
"quantity": 0.5,
"name": "Australian Lamb Leg (Sirloin Chops, Boneless, Trimmed to 1/8\" Fat)",
"brand": null,
"description": "1 lb",
"meal_type": "breakfast",
"calories": 471.5,
"carbohydrate": 0,
"protein": 41.57,
"fat": 32.615,
"saturated_fat": 15.6445,
"polyunsaturated_fat": 1.472,
"monounsaturated_fat": 13.3315,
"trans_fat": null,
"cholesterol": 149.5,
"sodium": 134,
"potassium": 698.5,
"fiber": null,
"sugar": null
}]
}
}
The fetch request block I'm using is as follows:
[[RKObjectManager sharedManager] addFetchRequestBlock:^NSFetchRequest *(NSURL *URL) {
RKPathMatcher *pathMatcher = [RKPathMatcher pathMatcherWithPattern:#"nutrition/days/:date"];
NSDictionary *argsDict = nil;
BOOL match = [pathMatcher matchesPath:[URL relativePath] tokenizeQueryStrings:NO parsedArguments:&argsDict];
NSDate *date;
if (match) {
date = [[[RDFormatters sharedManager] dashFormatUTC] dateFromString:[argsDict objectForKey:#"date"]];
NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:#"FoodEntry"];
fetchRequest.predicate = [NSPredicate predicateWithFormat:#"day.date = %#", date];
return fetchRequest;
}
return nil;
}];
This FetchRequest returns all the FoodEntries associated with the day call, however, I do not think I'm performing the call correctly. I realize this because
It crashes (duh!)
The response of the API call is usually a Day object, but after performing the FetchRequest it becomes a FoodEntry object – the very same FoodEntry object I'm attempting to delete.
Is there a way to delete orphaned objects in relationships via Restkit? What's the proper method for this?
================================
Here is the crash log
2014-07-25 08:38:18.158 Euco[6918:60b] I restkit.network:RKObjectRequestOperation.m:180 GET 'https://example.com/api/v1/nutrition/days/2014-07-24'
2014-07-25 08:38:18.831 Euco[6918:f03] I restkit.network:RKObjectRequestOperation.m:250 GET 'https://example.com/api/v1/nutrition/days/2014-07-24' (200 OK / 4 objects) [request=0.6671s mapping=0.0053s total=0.6881s]
2014-07-25 08:38:18.831 Euco[6918:60b] -[FoodEntry nutrition_plan]: unrecognized selector sent to instance 0x10ab5ff20
(lldb) po self.day
<FoodEntry: 0x10ab5ff20> (entity: FoodEntry; id: 0xd000000000040012 <x-coredata://1CAD1FBC-F8EE-4A9C-A1B4-7DCDF2A5F1D7/FoodEntry/p1> ; data: <fault>)
2014-07-25 08:38:58.103 Euco[6918:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[FoodEntry nutrition_plan]: unrecognized selector sent to instance 0x10ab5ff20'
*** First throw call stack:
(
0 CoreFoundation 0x00000001038a1495 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x00000001032c299e objc_exception_throw + 43
2 CoreFoundation 0x000000010393265d -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
3 CoreFoundation 0x0000000103892d8d ___forwarding___ + 973
4 CoreFoundation 0x0000000103892938 _CF_forwarding_prep_0 + 120
5 Euco 0x0000000100036ff8 -[JournalNutritionViewController numberOfSectionsInTableView:] + 88
6 UIKit 0x00000001024ec8e2 -[UITableViewRowData(UITableViewRowDataPrivate) _updateNumSections] + 86
7 UIKit 0x00000001024ed5b5 -[UITableViewRowData invalidateAllSections] + 66
8 UIKit 0x000000010238b0cc -[UITableView _updateRowData] + 191
9 UIKit 0x000000010239c225 -[UITableView noteNumberOfRowsChanged] + 91
10 UIKit 0x000000010239bd27 -[UITableView reloadData] + 717
11 Euco 0x00000001000368c8 __42-[JournalNutritionViewController setDate:]_block_invoke + 184
12 Euco 0x0000000100067f7e __57+[Day(ModelFunctions) read:withType:withSuccess:failure:]_block_invoke + 142
13 Euco 0x0000000100200b3b __66-[RKObjectRequestOperation setCompletionBlockWithSuccess:failure:]_block_invoke242 + 91
14 libdispatch.dylib 0x0000000103e50851 _dispatch_call_block_and_release + 12
15 libdispatch.dylib 0x0000000103e6372d _dispatch_client_callout + 8
16 libdispatch.dylib 0x0000000103e533fc _dispatch_main_queue_callback_4CF + 354
17 CoreFoundation 0x00000001038ff289 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
18 CoreFoundation 0x000000010384c854 __CFRunLoopRun + 1764
19 CoreFoundation 0x000000010384bd83 CFRunLoopRunSpecific + 467
20 GraphicsServices 0x0000000104af0f04 GSEventRunModal + 161
21 UIKit 0x00000001022d7e33 UIApplicationMain + 1010
22 Euco 0x0000000100063113 main + 115
23 libdyld.dylib 0x00000001040b45fd start + 1
24 ??? 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
When I add an exception breakpoint, it stops here before crashing:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return self.day.nutrition_plan.meal_goals.count
}
When it breaks there, if I run po self.day in the console, it returns <FoodEntry: 0x10ab5ff20> so it is somehow thinking the Day object is a FoodEntry object.

Answer 1

From your description your orphan block looks fine. It verifies the URL that is being processed so should be auctioned at the appropriate times.
This code:
self.day = (Day *)mappingResult.firstObject;
is a risk in a number of cases because you can't always be sure what the first object in the mapping result will be. If:
You have multiple mapped objects (nested)
You have multiple response descriptors (which leads to 1.)
then the mapping result should be queried as a dictionary and you should check the contents before casting them to what you hope they are. Basically never access the mapping result as an array.