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POInserted object is not reflected in the query results with NSFetchRequest
 

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  1. POInserted object is not reflected in the query results with NSFetchRequest
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    <p>I've just started playing with the iOS development and Core Data technology.</p> <p>What I am trying to do is to insert object into the Core Data and then run fetch request within same context looking for the newly inserted object.</p> <p>Here is the code I am using to insert the object:</p> <pre><code>+(Reward*) rewardForAction: (Actions) action inManagedObjectContext: (NSManagedObjectContext *) context { NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Reward"]; NSPredicate *actionPredicate = [NSPredicate predicateWithFormat:@"action = %@", [NSString stringWithFormat:@"%i", action]]; NSPredicate *todayPredicate = [NSPredicate predicateWithFormat:@"when &gt; %@", [NSDate today]]; NSLog(@"Today's midnight :%@", [NSDate today]); request.predicate = [NSCompoundPredicate andPredicateWithSubpredicates: [NSArray arrayWithObjects: actionPredicate, todayPredicate, nil]]; NSError *error = nil; NSArray *matches = [context executeFetchRequest: request error: &amp;error]; Reward *reward = nil; if(!matches) { NSLog(@"ERROR: failed to retrieve rewards"); } else if(matches.count &gt; 0) { NSLog(@"WRONG: reward already exists"); } else { reward = [NSEntityDescription insertNewObjectForEntityForName:@"Reward" inManagedObjectContext:context]; reward.action = [NSNumber numberWithInt:action]; reward.when = [NSDate date]; reward.pointsEarned = [Reward getPointsForAction:action]; } [Stats track: context]; [context save:nil]; return reward; } </code></pre> <p>This code first checks if reward is already given today for some action and if not it gives a reward. </p> <p>calling this method twice with same parameters, like this</p> <p>[Reward rewardForAction:APPLICATION_LAUNCH inManagedObjectContext: self.db.managedObjectContext]; [Reward rewardForAction:APPLICATION_LAUNCH inManagedObjectContext: self.db.managedObjectContext];</p> <p>expected to result in inserting only one object.</p> <p>But, in fact it inserts two objects into the Core Data. In the debugger I see second fetch request returns no objects when one is already there.</p> <p>Looks like NSFetchRequest does not see changes in the data store and operating will on old data. Am I missing something ? </p> <p><strong>EDIT:</strong> I have also set up observer for the NSManagedObjectContextObjectsDidChangeNotification and when it gets called I am calculating sum of the points to reflect it on the UI. Unfortunately sum also does not contain points from the inserted object. Here is my code to calculate sum:</p> <pre><code>+(NSInteger) getPoints: (NSManagedObjectContext *) context { Stats * stats= [Stats get: context]; NSArray *args = [NSArray arrayWithObject: [NSExpression expressionForKeyPath:@"pointsEarned"]]; NSExpression *ex = [NSExpression expressionForFunction:@"sum:" arguments:args]; NSExpressionDescription *ed = [[NSExpressionDescription alloc] init]; [ed setName:@"result"]; [ed setExpression:ex]; [ed setExpressionResultType:NSInteger32AttributeType]; NSFetchRequest *request = [[NSFetchRequest alloc] init]; [request setPropertiesToFetch:[NSArray arrayWithObject:ed]]; [request setResultType:NSDictionaryResultType]; /*if([stats intervalStartDate]) { NSPredicate *predicate = [NSPredicate predicateWithFormat:@"when &gt;= %@", [stats intervalStartDate]]; [request setPredicate:predicate]; }*/ NSEntityDescription *entity = [NSEntityDescription entityForName:@"Reward" inManagedObjectContext:context]; [request setEntity:entity]; NSArray *results = [context executeFetchRequest:request error:nil]; if(results &amp;&amp; results.count &gt; 0) { NSDictionary *resultsDictionary = [results objectAtIndex:0]; NSNumber *resultValue = [resultsDictionary objectForKey:@"result"]; return [resultValue intValue]; } else { return 0; } } </code></pre> <p>Strangely enough when I stop the app on the simulator and run it again. I can see all points as I expect.</p>
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    1. This table or related slice is empty.
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    1. USDenys Nikolayenko
    1. USDenys Nikolayenko
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
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    1. This table or related slice is empty.
    1. COI suspect the problem lies with one or both of your predicates. Try commenting out request.predicate= and see if you're able to add two rows? If not, then diagnose those predicates.
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      1. POInserted object is not reflected in the query results with NSFetchRequest
      1. USCSmith
    2. COIndeed the problem was with the actionPredicate as pointed in the answer
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      1. POInserted object is not reflected in the query results with NSFetchRequest
      1. USDenys Nikolayenko
    3. COI have another puzzle I put into the edit
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      1. POInserted object is not reflected in the query results with NSFetchRequest
      1. USDenys Nikolayenko
 

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