NSPredicate - not working as expected.

[stephen]

Hello,

I trying to select certain record types from my database, using NSPredicate, but its not working as expected. Its not selecting any records at all. When I comment out the NSPredicate lines the Fetch Request works with no problems, selecting all the records in my database.

 NSString *mapIDx = @"98";
    NSLog(@"map id: %@", mapIDx);

    NSFetchRequest *request = [[NSFetchRequest alloc] init];

    NSEntityDescription *entity = [NSEntityDescription entityForName:@"WayPoint" inManagedObjectContext:managedObjectContext];
    [request setEntity:entity];

    //NSPredicate *predicate = [NSPredicate predicateWithFormat:@"waypoint_map_id=%@", mapIDx];
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"waypoint_map_id==%@", mapIDx];
    [request setPredicate:predicate];

    NSError *error;
    listArray = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy];
    [request release];


    int arrayItemQuantity =[listArray count];
    NSLog(@"Array Quantity: %d", arrayItemQuantity);

    // Loop through the array and display the contents.
    int i;
    for (i = 0; i < arrayItemQuantity; i++)
    {
        NSLog (@"Element %i = %@", i,[listArray objectAtIndex: i]);
    }

    /*
    NSInteger *xCoordinate = listArray[1];
    NSInteger *yCoordinate = listArray[3];
    NSLog(@"xCoordinate: %@", xCoordinate);
    NSLog(@"yCoordinate: %@", yCoordinate);

    CLLocationCoordinate2D coordinate = {xCoordinate, yCoordinate};
    MapPin *pin = [[MapPin alloc]initwithCoordinates:coordinate];
    [self.mapView addAnnotation:pin];
    [pin release];
    */
[listArray release];

Anyone any thoughts ?

Regards,
Stephen

[czasalad]

hello,

i think the code here:

 NSPredicate *predicate = [NSPredicate predicateWithFormat:@"waypoint_map_id==%@", mapIDx];
    [request setPredicate:predicate];

is the problem, seems to me that waypoint_map_id is a number.. while mapIDx is a NSString.....

if waypoint_map_id is a NSString, then that == will never be true, since
u need to use string comparison, instead of == since that just compares the pointers

don't know if that's correct, but it's worth a try

[stephen]

waypoint_map_id is a string. Could you post some sample code for string comparison.

[stephen]

Problem solved:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"waypoint_map_id contains[cd] %@", mapIDx];
	[request setPredicate:predicate];

[Yellow]

congrats dude! and thanks for posting up the solution!