coredata subquery with multiple conditions / relations - core-data

Question

I have the following model:
how can I get all the PT objects where groupId == '2'?
I have tried several ways, but without success.
With this query, I get one result only:
NSFetchRequest *request = [[NSFetchRequest alloc] init];
request.entity = [NSEntityDescription entityForName:#"Status" inManagedObjectContext:self.managedObjectContext];
request.predicate = [NSPredicate predicateWithFormat:#"group.groupId == %#", [NSNumber numberWithInt:2]];
NSError *error = nil;
NSArray *resultSet = [self.managedObjectContext executeFetchRequest:request error:&error];
[request release];
NSLog(#"array count: %lu", (unsigned long)[resultSet count]);
NSPredicate *thePredicate = [NSPredicate predicateWithFormat:#"hasBeenDeleted == %# AND (ANY hasStatus IN %#)",
[NSNumber numberWithBool:NO],
[NSSet setWithArray:resultSet]];
[self.ptListViewController refreshDataWithPredicate:thePredicate];

Answer 1

You could start with a template "GROUP_BY_GROUP_ID" and add it to the managedObjectModel ...
- (NSManagedObjectModel *)managedObjectModel {
// The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
if (_managedObjectModel != nil) {
return _managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"GroupdId2" withExtension:#"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
NSFetchRequest *tmpTemplate;
NSEntityDescription *tmpEntity;
NSPredicate *tmpPredicate;
// 1. GROUP_BY_GROUP_ID
tmpEntity = [[_managedObjectModel entitiesByName] objectForKey:#"Group"];
tmpTemplate = [[NSFetchRequest alloc] init];
[tmpTemplate setEntity:tmpEntity];
tmpPredicate = [NSPredicate predicateWithFormat:#"(groupId == $value)"];
[tmpTemplate setPredicate:tmpPredicate];
[_managedObjectModel setFetchRequestTemplate:tmpTemplate forName:#"GROUP_BY_GROUP_ID"];
return _managedObjectModel;
}
Here is the appropriate fetch method:
- (NSArray *)fetchGroupByGroupId:(NSNumber *)value
{
NSError *error = nil;
NSManagedObjectModel *model = _managedObjectModel;
NSDictionary *substitutionDictionary = [NSDictionary dictionaryWithObjectsAndKeys:value, #"value", nil];
NSFetchRequest *fetchRequest = [model fetchRequestFromTemplateWithName:#"GROUP_BY_GROUP_ID" substitutionVariables:substitutionDictionary];
NSArray *results = [_managedObjectContext executeFetchRequest:fetchRequest error:&error];
return results;
}
Now you can start fetching PT entities like this (Xcode lets you generate the NSManagedObject subclasses for all entities):
NSArray *groups=[self fetchGroupByGroupId:#(2)];
NSMutableSet *resultPT=[[NSMutableSet alloc] init];
for (Group *group in groups) {
for (Status *status in group.hasStatus) {
for (PTStatus *ptstatus in status.ptStatus) {
if (ptstatus.targetPT!=nil) {
[resultPT addObject:ptstatus.targetPT];
}
if (ptstatus.pt!=nil) {
[resultPT addObject:ptstatus.pt];
}
}
}
}
In resultPT now you will find all different PT entities "with" groupId == '2'.
You find a XCode 6.1 project here: XCode 6.1 project on Dropbox.
Hope it helps.

Answer 2

I found it!
I had a bug when relating the Status with the Group.
Correct code for achieving:
NSFetchRequest *request = [[NSFetchRequest alloc] init];
request.entity = [NSEntityDescription entityForName:#"PTStatus" inManagedObjectContext:self.managedObjectContext];
request.predicate = [NSPredicate predicateWithFormat:#"ANY status.group.groupId == %#", [NSNumber numberWithInt:2]];
NSError *error = nil;
NSArray *resultSet = [self.managedObjectContext executeFetchRequest:request error:&error];
[request release];
NSLog(#"array count: %lu", (unsigned long)[resultSet count]);
NSPredicate *thePredicate = [NSPredicate predicateWithFormat:#"hasBeenDeleted == %# AND (ANY hasStatus IN %#)",
[NSNumber numberWithBool:NO],
[NSSet setWithArray:resultSet]];
[self.ptListViewController refreshDataWithPredicate:thePredicate];
and [self.ptListViewController refreshDataWithPredicate:thePredicate]; has
- (void)refreshDataWithPredicate:(NSPredicate *)predicate{
self.fetchedResultsController = nil;
[NSFetchedResultsController deleteCacheWithName:#"PTs_Cache"];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
request.entity = [NSEntityDescription entityForName:#"PT" inManagedObjectContext:self.managedObjectContext];
request.sortDescriptors = [NSArray arrayWithObjects:
[NSSortDescriptor sortDescriptorWithKey:#"requestDate" ascending:NO],
[NSSortDescriptor sortDescriptorWithKey:#"number" ascending:YES],
nil];
request.predicate = predicate;
request.fetchBatchSize = 40;
NSString *sectionNameKeyPathString = #"dateSection_transient";
NSFetchedResultsController *frc = [[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:sectionNameKeyPathString
cacheName:#"PTs_Cache"];
[request release];
self.fetchedResultsController = frc;
[frc release];
[self.theTable reloadData];
}