I have a problem, and I reckon there's a really straightforward solution to it, but I can't fathom it out!
I have this piece of code:
NSManagedObjectContext * context = [[NSApp delegate] managedObjectContext];
NSManagedObjectModel * model = [[NSApp delegate] managedObjectModel];
NSDictionary * entities = [model entitiesByName];
NSEntityDescription * entity = [entities valueForKey:#"Post"];
NSPredicate * predicate;
predicate = [NSPredicate predicateWithFormat:#"date < %#", [NSDate date]];
NSSortDescriptor * sort = [[NSSortDescriptor alloc] initWithKey:#"date" ascending:YES];
NSArray * sortDescriptors = [NSArray arrayWithObject: sort];
NSFetchRequest * fetch = [[NSFetchRequest alloc] init];
[fetch setEntity: entity];
[fetch setPredicate: predicate];
[fetch setSortDescriptors: sortDescriptors];
NSArray * results = [context executeFetchRequest:fetch error:nil];
[sort release];
[fetch release];
This returns the specified data in an Array. I now want to display this data in a NSTableView.
How would I go about doing this?
Thanks!
You could use it as the data for an NSArrayController which you bind to the NSTableView.
Looks like you need to read into bindings.
Related
I need to perform a fetch from two different entities, merge them, and then sort them based on a field that both entities have: 'lastModifiedDate'. lastModifiedDate is NSDate
NSFetchRequest *fetchRequest1 = [[NSFetchRequest alloc] init];
NSFetchRequest *fetchRequest2 = [[NSFetchRequest alloc] init];
NSEntityDescription *entity1 = [NSEntityDescription entityForName:#"Entity1" inManagedObjectContext:self.managedObjectContext];
[fetchRequest1 setEntity:entity1];
NSEntityDescription *entity2 = [NSEntityDescription entityForName:#"Entity2" inManagedObjectContext:self.managedObjectContext];
[fetchRequest2 setEntity:entity2];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"lastModeifiedDate" ascending:NO];
NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor, nil];
[fetchRequest1 setSortDescriptors:sortDescriptors];
[fetchRequest2 setSortDescriptors:sortDescriptors];
[self.managedObjectContext executeFetchRequest:fetchRequest onSuccess:^(NSArray *results) {
[self.refreshControl endRefreshing];
self.objects = results; //objects is an array #property
[self.tableView reloadData];
} onFailure:^(NSError *error) {
[self.refreshControl endRefreshing];
NSLog(#"An error %#, %#", error, [error userInfo]);
}
I'm stuck here. I need to merge fetchRequest1 and fetchRequest2, and have the objects display in a tableViewController in descending order. Thanks.
You can not merge two fetch requests, but you could merge and sort the fetched arrays:
NSArray *results1 = ...; // from first fetch request;
NSArray *results2 = ...; // from second fetch request;
NSMutableArray *merged = [[NSMutableArray alloc] init];
[merged addObjectsFromArray:results1];
[merged addObjectsFromArray:results2];
[merged sortUsingDescriptors:#[sortDescriptor]];
Alternatively, you could define an entity "Entity", make that the parent entity
for "Entity1" and "Entity2", and define all common properties (such as
"lastModifiedDate") in the parent entity. Then you can fetch and sort "Entity" objects.
(A possible disadvantage of entity inheritance is that Core Data uses a single table for all
"Entity", "Entity1" and "Entity2" objects. This is not optimal if there are many
properties that are not common to both.)
this is the code in my AppDelegate.m:
-(IBAction)fetch:(id)sender{
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Foo" inManagedObjectContext:[self managedObjectContext]];
[fetchRequest setEntity:entity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"title == 'some title'"];
[fetchRequest setPredicate:predicate];
NSError *error = nil;
NSArray *fetchedObjects = [[self managedObjectContext] executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {NSLog(#"Error: %#", error);}
NSMutableArray *fooArray = [[NSMutableArray alloc]init];
for (Foo *f in fetchedObjects) {
//here another fastenum for a to-many relationship
for(Bar *b in f.relationship){
[fooArray addObject:b.title];
}
}
Everytime I perform the fetch action, even if I've changed the app.storedata file via UI and checked the changes in finder, the result is always the same until i quit the application. After a restart, the fetch result is up to date and aligned with the app.storedata file. The fooArray count is always the same, regardless if I add some entries in the entities and coredata save everything.
I've tried with [fetchRequest setIncludesPendingChanges:YES] but it doesn't affect the behaviour.
How to update the fetch result while the app is running?
UPDATE: i've "solved" the problem with this workaround:
-(IBACTION)fetch:(id)sender{
_managedObjectContext = nil;
_persistenStoreCoordinator = nil;
//rest of the code...
Is this workaround a final solution? Is there a more "correct" way to solve this problem?
I am trying to filter a fetchRequest.
I'm at the point where the result is loaded into an NSArray.
However, I need to parse the array to pull out the individual items - right now, they look as if they were one object.
The code I'm using to get to this point is:
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSManagedObjectContext *moc = coreDataController.mainThreadContext;
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Category" inManagedObjectContext:moc];
[request setEntity:entity];
// Order the events by name.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"name" ascending:YES];
[request setSortDescriptors:#[sortDescriptor]];
// Execute the fetch -- create a mutable copy of the result.
NSError *error = nil;
NSArray *categories = [[moc executeFetchRequest:request error:&error] mutableCopy];
if (categories == nil) {
NSLog(#"bugger");
}
NSObject *value = nil;
value = [categories valueForKeyPath:#"name"];
This results as follows:
value = (
)
[DetailViewController loadPickerArray]
[AppDelegate loadPickerArray]
value = (
"Cat Two",
"Cat Three",
"Cat One",
"Cat Four"
)
Also, please note that the first time this ran, there were no results. I get that about 50% of the time.
Thanks for any help.
There are several methods you can filter your data.
The preferred way is to use a predicate for your search. This will give you the best performance.
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSManagedObjectContext *moc = coreDataController.mainThreadContext;
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Category" inManagedObjectContext:moc];
[request setEntity:entity];
// Order the events by name.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"name" ascending:YES];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"name CONTAINS[CD] %#", #"Cat"]; //This will return all objects that contain 'cat' in their name property.
[request setPredicate:predicate];
[request setSortDescriptors:#[sortDescriptor]];
// Execute the fetch -- create a mutable copy of the result.
NSError *error = nil;
NSArray *categories = [moc executeFetchRequest:request error:&error];
if (categories == nil) {
NSLog(#"bugger");
}
//Here you have the objects you want in categories.
for(Category *category in categories)
{
NSLog(#"Category name: %#", category.name);
}
If you wish to filter using an array, the following is possible also:
NSMutableArray *categories = [[moc executeFetchRequest:request error:&error] mutableCopy];
[categories filterUsingPredicate:[NSPredicate predicateWithFormat:[NSPredicate predicateWithFormat:#"name CONTAINS[CD] %#", #"Cat"]]
//Now, the only objects left in categories will be the ones with "cat" in their name property.
I recommend reading the Predicates Programming Guide, as predicates are very powerful, and it is much more efficient to filter your results in the store.
i have a tableview which is populated with NSFetchedResultsController.
On didSelectRowAtIndexPathi am updating the current row. The sorting here should not change. The difference in the selected row is, that i mark it as read. No title changes or something.
In iOS4 the row gets updated and still leave on his current place, it does not move to the end of section. Thats the right way.
in iOS5 the row gets also updated but it moves to the end of the Section. I want to prevent that. How can i do that? And why is that happening?
See my code:
- (NSFetchedResultsController *)fetchedResultsController
{
if (__fetchedResultsController != nil)
{
return __fetchedResultsController;
}
NSFetchRequest *fetchRequest = [[[NSFetchRequest alloc] init] autorelease];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"EntitySetsCardsInbox" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
NSPredicate *inboxPred = [NSPredicate predicateWithFormat:#"archived == 0 AND cardId != 0"];
[fetchRequest setPredicate:inboxPred];
if (sortString == nil) {
//sortString = [[NSString alloc] initWithString:#"sortingOrder"];
sortString = [[NSString alloc] initWithString:#"colorOrder"];
sortAsc = NO;
}
if ([sortString isEqualToString:#"cardTitle"]) {
NSSortDescriptor *sortDescriptor2 = [[[NSSortDescriptor alloc] initWithKey:sortString ascending:sortAsc selector:#selector(localizedCaseInsensitiveCompare:)] autorelease];
NSArray *sortDescriptors = [[[NSArray alloc] initWithObjects:sortDescriptor2, nil] autorelease];
[fetchRequest setSortDescriptors:sortDescriptors];
XLog(#"sortDescriptors: %#", sortDescriptors);
} else {
NSSortDescriptor *sortDescriptor2 = [[[NSSortDescriptor alloc] initWithKey:sortString ascending:sortAsc] autorelease];
NSArray *sortDescriptors = [[[NSArray alloc] initWithObjects:sortDescriptor2, nil] autorelease];
[fetchRequest setSortDescriptors:sortDescriptors];
XLog(#"sortDescriptors: %#", sortDescriptors);
}
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:nil];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
[...]
}
i think your sortdescriptor is changing when you updating your rows. add one more sortdescriptor to fix the list with it and check it again. in my case i have a very similar issue and it solved my problem. maybe yours, too.
Here is my problem :
My CoreData model have two entity : Players and Results. The important properties of Players are :
- ratingTypePlayer, which is a String.
- resultsPlayer which is a Too-Many Relationship with Results as Destination. The Inverse relationship is playerResult.
I wish to obtain an array with all the Results of the Players which ratingTypePlayer is equal to "Toto". I don't find this kind of example.
Thanks a lot
You mean, like a fetch request?
NSManagedObjectContext *context = [[NSApp delegate] managedObjectContext];
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
[request setEntity:[NSEntityDescription entityForName:#"Player" inManagedObjectContext:context]];
[request setPredicate:[NSPredicate predicateWithFormat:#"ratingTypePlayer == %#", #"Toto"]];
NSArray *players = [context executeFetchRequest:request error:nil];
If you wanted an array of the "resultsPlayer" relationships, you could do:
NSArray *results = [players valueForKey:#"resultsPlayer"];