When i am using the NSPredicate while fetch the unique user data from Coredata Entity the app getting crash. But, no error logs. This is the code am using,
if (managedObjectContext == nil)
{
managedObjectContext = [(AppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
}
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"Name==%#",selectedUserName];
NSFetchRequest *fectchreq = [[NSFetchRequest alloc] init];
NSEntityDescription *entitydes = [NSEntityDescription entityForName:#"ALLData" inManagedObjectContext:managedObjectContext];
[fectchreq setEntity:entitydes];
[fectchreq setPredicate:predicate];
NSSortDescriptor *sortdes = [[NSSortDescriptor alloc] initWithKey:#"Name" ascending:YES];
NSArray *sortdesarray = [[NSArray alloc] initWithObjects:sortdes, nil];
[fectchreq setSortDescriptors:sortdesarray];
[sortdes release];
[sortdesarray release];
NSError *error = nil;
//NSMutableArray *storeddata = [[[managedObjectContext executeFetchRequest:fectchreq] error:&error] mutableCopy];
NSArray *storeddata = [managedObjectContext executeFetchRequest:fectchreq error:&error];
//[fectchreq release];
NSLog(#"StoreData : %#, count : %d",storeddata, [storeddata count]);
Can anyone please help to solve this problem? THanks in advance.
NSError *error;
NSMutableArray *storeddata = [managedObjectContext executeFetchRequest:fectchreq error:error];
You need to change this code to:
NSError *error = nil;
NSArray *storeddata = [managedObjectContext executeFetchRequest:fectchreq error:&error];
Reasons:
The error argument should be passed as a pointer because the declaration is -executeFetchRequest:(NSFetchedRequest *)request error:(NSError **)error;
Also this method returns NSArray, not NSMutableArray - you must be getting compiler warning about this...
Related
I'm doing a fetch of data to show it in a UITableView, I do the fetch but I want to sort them by date of creation or by any sort method.
Here is the method:
-(NSArray *) lesStations {
NSManagedObjectContext *moc = [[AppDelegate sharedAppDelegate]managedObjectContext];
NSFetchRequest *fetch = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Station" inManagedObjectContext:moc];
[fetch setEntity:entity];
NSError *error;
NSArray *result = [moc executeFetchRequest:fetch error:&error];
if (!result) {
return nil;
}
return result;
}
This should work
-(NSArray *) lesStations {
NSManagedObjectContext *moc = [[AppDelegate sharedAppDelegate]managedObjectContext];
NSFetchRequest *fetch = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Station" inManagedObjectContext:moc];
[fetch setEntity:entity];
NSError *error;
NSArray *result = [moc executeFetchRequest:fetch error:&error];
if (!result) {
return nil;
}
NSSortDescriptor *sort = [[NSSortDescriptor alloc] initWithKey:"creationDate" ascending:YES];
NSArray *sortedResults = [result sortedArrayUsingDescriptors:[NSArray arrayWithObject:sort]];
[sort release];
return sortedResults;
}
You have 2 options: get the results sorted or sort the NSArray with the results:
NSFetchRequest could be set a NSArray of NSSortDescriptor
NSSortDescriptor *sort = [[NSSortDescriptor alloc] initWithKey:#"place" ascending:NO]; //the key is the attribute you want to sort by
[fetchRequest setSortDescriptors:[NSArray arrayWithObject:sort]];
You can also sort the returned NSArray (see all instance methods of NSArray starting with sortedArray...)
I suggest using the first approach when working with CoreData. The second one is just informative when working with arrays...
You can sort fetch results by setting sortDescriptors for fetch, e.g.
fetch.sortDescriptors = [NSArray arrayWithObjects:[[NSSortDescriptor alloc] initWithKey: ascending: selector:], nil];
NSError *error;
NSArray *result = [moc executeFetchRequest:fetch error:&error];
The static analyzer keeps telling me that I have a +1 retain count for my request object and instruments tells me there is a leak there. However, no matter where I try to release it, it keeps crashing my app. It's the same with NSPredicate object. Please do help, I'm trying to meet a deadline.
// Fetch Requests
// Method that returns an array of NSManagedObjects in the managedObjectContext with a predicate of who ordered
- (NSArray *)fetchDataWithEntity:(NSString *)entity andSortKey:(NSString *)key andPerson:(Person *)whoOrdered
{
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entityDescription = [NSEntityDescription entityForName:entity
inManagedObjectContext:managedObjectContext];
request.entity = entityDescription;
// Handling Sorting
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:key ascending:YES
selector:#selector(compare:)];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors];
[sortDescriptor release];
[sortDescriptors release];
// Handling Predicate
if (whoOrdered) {
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"%# == whoOrdered", whoOrdered];
[request setPredicate:predicate];
}
NSError *error = nil;
NSArray *mutableFetchResults = [managedObjectContext executeFetchRequest:request error:&error];
//[request release];
[error release];
if (mutableFetchResults == nil) {
// Handle the error
}
return mutableFetchResults;
}
There is no need to release the error object since you are not the owner of it and you should release the request object just before returning the mutableFetchResults object since you are creating it using alloc and thus are the owner of it ...
Im trying to save a list of Device classes (a custom class) using Core Data and retrieve it. But After I save it, my query, which is VERY simple, doesnt return any records.
My call to save the records always returns YES and no errors:
BOOL resultOfSave = [managedObjectContext save:&err];
My predicate for searching by the property userLogin is like so:
- (NSArray *) devicesForUser:(NSString *)username
{
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Device" inManagedObjectContext:managedObjectContext];
[request setEntity:entity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"userLogin = %#", username];
[request setPredicate:predicate];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"macAddress" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors];
[sortDescriptors release];
[sortDescriptor release];
NSError *error = nil;
NSArray *fetchResults = [managedObjectContext executeFetchRequest:request error:&error];
if (fetchResults == nil) {
// Handle the error.
NSLog(#"ERROR: nil fetch result array");
}
[request release];
NSLog(#"devicesForUser [%#] count %d", username, [fetchResults count]);
return fetchResults;
}
but I always get zero results, if I get rid of the predecate, I get all the objects, and if I loop through them I can see that the userLogin property for at least one of the object IS set to the username that I pass in...
Has anyone ever had an issue like this???
Thanks for any help you can give
Mark
In your predicate, change:
#"userLogin = %#"
...to:
#"userLogin == %#"
I want to retrieve a single value (String) from "Entry." I believe I am missing something. Can someone point it out?
XYZAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *managedObjectContext = appDelegate.managedObjectContext;
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"name == %#", entryToSearchFor];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Entry" inManagedObjectContext:managedObjectContext];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"name" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors];
[request setEntity: entity];
[request setPredicate: predicate];
NSArray *results = [managedObjectContext executeFetchRequest:request error:nil];
if (results == nil) {
NSLog(#"No results found");
}else {
NSLog(#"entryToSearchFor %#", entryToSearchFor);
NSLog(#"results %#", [results objectAtIndex:0]);
}
Btw, the NSLog results outputs the following:
results <NSManagedObject: 0x3d2d360> (entity: Entry; id: 0x3d13650 <x-coredata://6EA12ADA-8C0B-477F-801C-B44FE6E6C91C/Entry/p3> ; data: <fault>)
NSFetchRequest will return an array of NSManagedObjects that matches the request. That is consistent with what you are seeing. Assuming you want to fetch the name, you can do NSLog(#"the name is %#", [[results objectAtIndex:0] name]); to print out the name.
I have completed and reproduced Core Data tutorials using a tableview to display contents. However, I want to access an Entity through a fetch on a view without a tableview. I used the following fetch code, but the count returned is always 0. The data exists when the database is opened using SQLite tools.
NSManagedObject *entryObj;
XYZDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *managedObjectContext = appDelegate.managedObjectContext;
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Quote" inManagedObjectContext:managedObjectContext];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"id" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors];
[request setEntity: entity];
NSArray *results = [managedObjectContext executeFetchRequest:request error:nil];
if (results == nil) {
NSLog(#"No results found");
entryObj = nil;
}else {
NSLog(#"results %d", [results count]);
}
[request release];
[sortDescriptors release];
count returned is always 0; it should be 5.
Can anyone point me to a reference or tutorial regarding creating a controller not to be used with a tableview.
As far as I can tell, everything looks fine (except I'm a little worried about using 'id' as an attribute name, since it's a keyword in Objective-C). Try removing the sort descriptor and see if that changes anything. Also, add an error check. Perhaps something is happening that that can tell you. And I assume "Quote" is the right name for the entity. If none of that helps, I don't think the problem is in the fetch request.
For what it's worth, here's how I would write it:
XYZDelegate * appDelegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext * context = appDelegate.managedObjectContext;
NSFetchRequest * request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Quote" inManagedObjectContext:context];
NSSortDescriptor * sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"id" ascending:YES];
[request setSortDescriptors:[NSArray arrayWithObject:sortDescriptor]];
[sortDescriptor release];
[request setEntity:[NSEntityDescription entityForName:#"Quote" inManagedObjectContext:context]];
NSError * error = nil;
NSArray *results = [context executeFetchRequest:request error:&error];
[request release];
if (error) {
NSLog(#"ERROR: %# %#", [error localizedDescription], [error userInfo]);
}
if (results == nil) {
NSLog(#"No results found");
entryObj = nil;
}
else {
NSLog(#"results %d", [results count]);
}