I have an SearchStringTooltip ManagedObject. With property #dynamic tooltipText; (NSString)
I need to dynamically add new tooltips in database, but I need only unique values (insensitive).
They could come in more than 100 per one time; and every time I check for unique..
It looks like:
if (newTooltips.count == 0)
return;
NSEntityDescription *entity = [NSEntityDescription
entityForName:#"SearchStringTooltip"
inManagedObjectContext:self.moc];
NSFetchRequest *request = [NSFetchRequest new];
[request setEntity:entity];
for (NSString *name in newTooltips) {
[request setPredicate:[NSPredicate predicateWithFormat:#"tooltipText = %#", name]]; //like = (=) + time *2(sometimes *3) ofcourse i know i need like.. Its insensitive
NSInteger count = [self.moc countForFetchRequest:request error:nil]; //But its is very expensive operation expensive
if (count > 0) {
continue;
}
DBSearchStringTooltip *tooltip = [NSEntityDescription insertNewObjectForEntityForName:#"SearchStringTooltip"
inManagedObjectContext:self.moc];
tooltip.tooltipText = name;
}
How can I do it more cheaply for memory? There can be > 10 000 tooltips for check unique... And I have to check them all.
Quick answer and I am sure more efficient. Use this code snippet instead of your loop:
[request setPredicate:[NSPredicate predicateWithFormat:#"tooltipText IN %#", newTooltips]];
[request setResultType:NSDictionaryResultType];
[request setPropertiesToFetch:#[#"tooltipText"]];
NSArray* result = [self.moc executeFetchRequest:request error:nil];
NSArray* existingTooltipNames = [result valueForKey:#"tooltipText"];
NSMutableOrderedSet* itemsToAdd = [NSMutableOrderedSet orderedSetWithArray:newTooltips];
[itemsToAdd minusSet:[NSSet setWithArray:existingTooltipNames]];
for (NSString *name in itemsToAdd) {
DBSearchStringTooltip *tooltip = [NSEntityDescription insertNewObjectForEntityForName:#"SearchStringTooltip" inManagedObjectContext:self.moc];
tooltip.tooltipText = name;
}
You may try to fetch only distinct tooltipText via NSDictionaryResultType result type of the fetch request and setReturnsDistinctResults:YES. Then search the results in memory. This could be much faster then 10k fetches, as far as fetch always hits the disk.
You may find more info here.
Related
I'm using Core Data to cache data, here is my code to insert object:
//data array count is 15
for (NSDictionary *dictionary in dataArray)
{
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"CacheData" inManagedObjectContext:context];
[request setEntity:entity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"title LIKE '%#'",dictionary[#"title"]];
[request setPredicate:predicate];
NSArray *fetchArray = [context executeFetchRequest:request error:NULL];
if ([fetchArray count] == 0)
{
CacheData *cacheData = [NSEntityDescription insertNewObjectForEntityForName:#"CacheData" inManagedObjectContext:context];
[cacheData setTitle:dictionary[#"title"]];
[cacheData setLink:dictionary[#"link"]];
[cacheData setPublishDate:dictionary[#"pubDate"]];
NSError *insertError = nil;
if (![context save:&insertError])
{
return NO;
}
}
}
The count of dataArray is 15, so I should insert 15 items to Core Data.
But once I used NSFetchRequest to fetch items, the array count returned added 1, and become 16, and fetch items again, it added 1 to 17 again:
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"CacheData" inManagedObjectContext:[[CacheDataManagement sharedInstance] managedObjectContext]];
[request setEntity:entity];
NSArray *fetchArray = [[[CacheDataManagement sharedInstance] managedObjectContext] executeFetchRequest:request error:NULL];
for (CacheData *data in fetchArray) {
NSLog(#"fetch:%#",[data title]);
}
NSLog(#"%ld",[fetchArray count]); //fetch array count is 16
Something wrong with my code ?
Update
Changed if ([fetchArray count] != 0) { … } to if ([fetchArray count] == 0) { … }
Since the problem it's not quite clear to me (I would like to have more details), I'll try to give you some hints.
First, the save should be done outside the for loop (In addition it's not correct to do a return within it).
// for in loop here
NSError *insertError = nil;
if (![context save:&insertError]) {
NSLog("%#", insertError);
return NO; // do it if the method you are running in returns a bool
}
Second, to check for duplicated you should rely on a GUID but if don't have it the predicate should look like the following.
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"title == %#",dictionary[#"title"]];
Third, also the execute for executeFetchRequest:error: should be replace with countForFetchRequest:error: since you don't need to return the objects but only a count. According to Apple doc, it
Returns the number of objects a given fetch request would have
returned if it had been passed to executeFetchRequest:error:.
Finally, in the for loop you are executing a request each time. My suggestion is to move execute a request before the loop and then checking for results within it. This according to Implementing Find-or-Create Efficiently. In this case, the pattern will enforce you to have a GUID for you entity.
Obviously, these are just hints. The real way to find the problem is to debug. In addition, I will perform tests starting from a fresh environment, i.e. the app has been deleted from the simulator or device.
In your code [fetchArray count] != 0 checks the inserting data is already exists. Try changing it like
if ([fetchArray count] == 0)
{
CacheData *cacheData = [NSEntityDescription insertNewObjectForEntityForName:#"CacheData" inManagedObjectContext:context];
[cacheData setTitle:dictionary[#"title"]];
[cacheData setLink:dictionary[#"link"]];
[cacheData setPublishDate:dictionary[#"pubDate"]];
NSError *insertError = nil;
if (![context save:&insertError])
{
return NO;
}
}
I have the following scenario. I have an app that handles data by using Core Data. I have an entity called "Brothers" which has 3 attributes: Name, Status, Age.
lets say that I have 1 record on my database that has:
-Name ==> Joe (String)
-Status ==> Married (String)
-Age ==> 28 (Integer)
I have an UIlabel a UItextfield and a Button. I want to be able to type the name (in this case Joe) on the UItextfield press the button and display the age (in this case 28) in the UILabel. I would also like to store the age value into a variable type integer so I can make some calculations with it later on.
below the code that I have inside the button.
NSEntityDescription *entitydesc = [NSEntityDescription entityForName:#"Brothers" inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc]init];
[request setEntity:entitydesc];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"age %d", [self.age.text integerValue]];
[request setPredicate:predicate];
NSError *error;
NSArray *integer = [context executeFetchRequest:request error:&error];
self.displayLabel.text = integer;
Update #1
I updated the code that i have inside the button and now i am able to search by the name and display the age. I'm still looking into storing the age as an integer into a variable so i can use it later on.
NSEntityDescription *entitydesc = [NSEntityDescription entityForName:#"Brothers" inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc]init];
[request setEntity:entitydesc];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"firstname like %#", self.firstnameTextField.text];
[request setPredicate:predicate];
NSError *error;
NSArray *integer = [context executeFetchRequest:request error:&error];
if(integer.count <= 0){
self.displayLabel.text = #"No records found";
}
else {
NSString *age;
for (NSManagedObject *object in integer) {
age = [object valueForKey:#"age"];
}
self.displayLabel.text = [NSString stringWithFormat:#"age: %#",age];
}
}
A predicate is an expression. If the expression evaluates to true then the predicate is satisfied. So if you were searching by age you'd use e.g.
[NSPredicate predicateWithFormat:#"age = %d", [self.age.text integerValue]]
Or by name:
[NSPredicate predicateWithFormat:#"name = %#", someNameOrOther]
Or by both:
[NSPredicate predicateWithFormat:#"(name = %#) and (age = %d)", someNameOrOther, [self.age.text integerValue]]
A fetch request gets the actual NSManagedObjects. So you'd get back an array of Brothers. Therefore you probably want something more like this to output a name:
if([array count])
self.displayLabel.text = [array[0] name];
Or for an age:
...
self.displayLabel.text = [[array[0] age] stringValue];
Or whatever other property you're outputting.
I think your predicate is wrong, the proper format would be this:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"age.integerValue == %d", [self.age.text integerValue]];
I have a very simple fetch request that i want to execute. One of my entities has an attribute called smartCollectionIds and it is of type transformable. I use this attribute to store an NSArray of simple strings. In my code i use an NSfetchedResultsController to populate a tableview. The predicate im using is as follows:
predicate=[NSPredicate predicateWithFormat:#"smartCollectionIds!=nil && (%# IN smartCollectionIds)",#"87F173A5-863D-4ECE-9673-A61D8F1E01FC-6285-000009A9CBAF3290"];
however this causes a crash, specifically at the pint when i perform a fetch. However, if i first use a fetch to load all my objects into an array, and then filter them out with the above predicate, the app does not crash, and i get my results as expected. So basically
THIS CODE BELOW DOES NOT WORK
-(void) tryTO
{
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Tweetary" inManagedObjectContext: [[ChubbyEyetwitterEngine sharedInstance] getManagedObjectContextForUse]];
NSPredicate *predicate;
predicate=[NSPredicate predicateWithFormat:#"smartCollectionIds!=nil && (%# IN smartCollectionIds)",#"87F173A5-863D-4ECE-9673-A61D8F1E01FC-6285-000009A9CBAF3290"];
NSSortDescriptor *secondarySortKey = [[[NSSortDescriptor alloc] initWithKey:#"created_at" ascending:FALSE] autorelease];
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease] ;
[request setEntity:entity];
[request setPredicate:predicate];
[request setSortDescriptors:[NSArray arrayWithObjects:
secondarySortKey
,nil]];
[request setFetchLimit:30]; //30
NSError *error;
NSArray *results = [[[ChubbyEyetwitterEngine sharedInstance] getManagedObjectContextForUse] executeFetchRequest:request error:&error];
if (error != nil)
{
NSLog(#"Results are %d",[results count]);
}else{
NSLog(#"findAllObjectsInContext error %#",error);
}
}
BUT THIS WORKS
NSArray *tweets = [Tweetary findAllObjectsInContext:[[ChubbyEyetwitterEngine sharedInstance] getManagedObjectContextForUse]];
NSLog(#"Before filter count is %d",[tweets count]);
predicate=[NSPredicate predicateWithFormat:#"smartCollectionIds!=nil && (%# IN smartCollectionIds)",#"87F173A5-863D-4ECE-9673-A61D8F1E01FC-6285-000009A9CBAF3290"];
predicate=[NSPredicate predicateWithFormat:#"smartCollectionIds!=nil && (%# IN smartCollectionIds)",#"87F173A5-863D-4ECE-9673-A61D8F1E01FC-6285-000009A9CBAF3290"];
NSArray *bNames = [tweets filteredArrayUsingPredicate:predicate];
NSLog(#"FINAL Results %d",[bNames count]);
+ (NSArray *)findAllObjectsInContext:(NSManagedObjectContext *)context;
{
#synchronized(self){
NSEntityDescription *entity = [self entityDescriptionInContext:context];
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
[request setEntity:entity];
NSError *error = nil;
NSArray *results = [context executeFetchRequest:request error:&error];
if (error != nil)
{
//handle errors
//NSLog(#"findAllObjectsInContext error %#",error);
}
return results;
}
}
In a nutshell, i need my fetch predicate to work when using NSfetchedResultsController instead of first loading up my objects into an array, and then applying my filter predicate. Can anyone point me in the right direction/ figure out why the predicate works only after i load my unfiltered data set into an array?
A Core Data fetch request with a predicate is translated to a SQLite query and executed
on the SQLite level. A transformable array is stored as some blob in the SQLite database,
therefore treating it as array in a fetch request does not work.
If you fetch the elements first, the blob is transformed back to an array
when the property is accessed. Therefore filtering the array of fetched objects works as expected.
I don't think there is any workaround. You cannot filter on transformable properties
in a fetch request.
So I'm adding a ListItem into ListName(There is a one to many relationship setted up) in a Class A
ListItem *newItem = [NSEntityDescription insertNewObjectForEntityForName:#"ListItem"
inManagedObjectContext:self.context];
//setting some attributes...
[listName addListItemsObject:newItem];
[self.context save:&error];
After that Class B is via a delegate methode called
There I want to get the data out of Core Data, BUT...If I'm fetching all ListName, the ListItems are not up to date(for example only 5 items instead of 6). If I fetch all ListItems then there are all there(6 out of 6).
What is wrong with my code...I need to get all ListNames though
NSError *error;
NSFetchRequest *req = [[NSFetchRequest alloc] init];
if(context == nil)
NSLog(#"context is nil");
NSEntityDescription *descr = [NSEntityDescription entityForName:#"ListName" inManagedObjectContext:self.context];
[req setEntity:descr];
NSSortDescriptor *sort = [[NSSortDescriptor alloc]initWithKey:#"lastModified" ascending:NO];
[req setSortDescriptors:[NSArray arrayWithObject:sort]];
NSArray * results = [self.context executeFetchRequest:req error:&error];
self.listNames = [results mutableCopy];
if ([results count] > 0) {
ListName *test = [results objectAtIndex:0];
[test.listItems count];
NSLog(#"item count on list %i", [test.listItems count]);
//wrong result
NSFetchRequest *newReq = [[NSFetchRequest alloc] init];
NSEntityDescription *descr = [NSEntityDescription entityForName:#"ListItem" inManagedObjectContext:self.context];
[newReq setEntity:descr];
NSArray * results2 = [self.context executeFetchRequest:newReq error:&error];
NSLog(#"item count on items %i", [results2 count]);
//right result
}
Given your data model and code, there is no reason that the count of ListItems in both places as to be the same because the counts are of two different sets of objects that do not necessarily overlap.
The first count is given by this code:
ListName *test = [results objectAtIndex:0];
[test.listItems count];
… which returns the count of ListItems objects in the relationship of a single, particular and unique ListName object. You may have one ListName object or you might have hundreds each of which could have an arbitrary number of related ListItems objects. This code will only count those related to he first ListName object returned.
The second count is given by:
NSFetchRequest *newReq = [[NSFetchRequest alloc] init];
NSEntityDescription *descr = [NSEntityDescription entityForName:#"ListItem" inManagedObjectContext:self.context];
[newReq setEntity:descr];
NSArray * results2 = [self.context executeFetchRequest:newReq error:&error];
NSLog(#"item count on items %i", [results2 count]);
… which returns an unfiltered array containing every instance of ListItems in the persistent store regardless of what relationships they have.
There is no particular reason to expect the first count to ever agree with the second because it will only do so when (1) you have a single ListNames object in the store and (2) every existing ListItems object is in that ListNames.listNames relationship.
Make sure not confuse entities and managed objects.
BTW, you should almost always use reciprocal relationships e.g. if you have ListNames.listItems you should have a reciprocal ListItems.listName.
A simple reset has helped
My situation is simple: I have some records in my core data store. One of their attributes is a string called "localId". There's a point where I'd like to find the record with a particular localId value. The obvious way to do this is with an NSFetchRequest and an NSPredicate. However, when I set this up, the request returns zero records.
If, however, I use the fetch request without the predicate, returning all records, and just loop over them looking for the target localId value, I do find the record I'm looking for. In other words, the record is there, but the fetch request can't find it.
My other methods in which I use fetch requests and predicates are all working as expected. I don't know why this one is failing.
I want to do this:
- (void)deleteResultWithLocalID:(NSString *)localId {
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:[NSEntityDescription entityForName:#"WCAAssessmentResult" inManagedObjectContext:context]];
[request setPredicate:[NSPredicate predicateWithFormat:#"localId == %#", localId]];
NSError *error = nil;
NSArray *results = [context executeFetchRequest:request error:&error];
NSAssert(error == nil, ([NSString stringWithFormat:#"Error: %#", error]));
if ([results count]) [context deleteObject:[results objectAtIndex:0]];
else NSLog(#"could not find record with localID %#", localId);
[self saveContext];
}
But I end up having to do this:
- (void)deleteResultWithLocalID:(NSString *)localId {
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:[NSEntityDescription entityForName:#"WCAAssessmentResult" inManagedObjectContext:context]];
NSError *error = nil;
NSArray *results = [context executeFetchRequest:request error:&error];
NSAssert(error == nil, ([NSString stringWithFormat:#"Error: %#", error]));
for (WCAAssessmentResult *result in results) {
if ([result.localId isEqualToString:localId]) {
NSLog(#"result found, deleted");
[context deleteObject:result];
}
}
[self saveContext];
}
Any clues as to what could be going wrong?
edit
I've found that I can use the predicate I'm creating to get the results I expect after the fetch request has been executed. So, the following also works:
- (WCAChecklistItem *)checklistItemWithId:(NSNumber *)itemId {
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:[NSEntityDescription entityForName:#"WCAChecklistItem" inManagedObjectContext:context]];
NSArray *foundRecords = [context executeFetchRequest:request error:nil];
foundRecords = [foundRecords filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"serverId == %#", itemId]];
if ([foundRecords count]) {
return [foundRecords objectAtIndex:0];
} else {
NSLog(#"can't find checklist item with id %#", itemId);
return nil;
}
}
UPDATE
I've come across someone else experiencing this very issue:
http://markmail.org/message/7zbcxlaqcgtttqo4
He hasn't found a solution either.
Blimey! I'm stumped.
Thanks!
If localId is a numerical value, then you should use an NSNumber object in the predicate formation instead of an NSString.
[request setPredicate:[NSPredicate predicateWithFormat:#"localId == %#",
[NSNumber numberWithString:localId]]];
NSPredicate format strings automatically quote NSString objects.
Hate to say it but the most common cause of these types of problems is simple typos. Make sure that your attribute names and the predicate are the same. Make sure that your property names and the attributes names are the same. If a reference to a property works but a reference to attribute name doesn't there is probably a mismatch.
You could test for the latter by comparing the return of:
[result valueForKey:#"localID"]
... with the return of:
result.localID