Core data NSFetchRequest also fetches children objects of the Entity

Question

I'm new to iOS dev and Core Data. I have a parent NSManagedObject

@class Units;
@interface Properties : NSManagedObject

@property (nonatomic, retain) NSString * descr;
@property (nonatomic, retain) NSString * address;
@property (nonatomic, retain) NSString * city;
@property (nonatomic, retain) NSString * state;
@property (nonatomic, retain) NSString *zipCode;
@property (nonatomic, retain) NSString * imageKey;
@property (nonatomic, retain) NSString * numberOfUnit;
@property (nonatomic, retain) NSData * thumbnailData;
@property (nonatomic, strong) UIImage * thumbnail;
@property (nonatomic) double orderingValue;
@property (nonatomic, retain) NSSet *units;

And a Child:

@class Properties;

@interface Units : Properties

@property (nonatomic, retain) NSString * unitDescr;
@property (nonatomic) int16_t unitNumber;
@property (nonatomic, retain) Properties *property;

When I fetch the Parent Properties with this method to display the parent Properties objects in a tableview:

- (void)loadAllItems
{
    if (!allItems) {
        NSFetchRequest *request = [[NSFetchRequest alloc] init];

        NSEntityDescription *e = [[model entitiesByName] objectForKey:@"Properties"];
        [request setEntity:e];

        NSSortDescriptor *sd = [NSSortDescriptor
                                sortDescriptorWithKey:@"orderingValue"
                                ascending:YES];
        [request setSortDescriptors:[NSArray arrayWithObject:sd]];

        NSError *error;
        NSArray *result = [context executeFetchRequest:request error:&error];
        if (!result) {
            [NSException raise:@"Fetch failed"
                        format:@"Reason: %@", [error localizedDescription]];
        }

        allItems = [[NSMutableArray alloc] initWithArray:result];
    }
}

I run in to a problem where the core data context fetches the child objects of the Parent Entity. I just want to return the Parent Objects.

For example, If I have a property with 3 units, the properties tableview should display just 1 row but it is displaying 4 rows (1 parent and 3 childs).

How do I just return the parent objects?

Thanks.

Answer 1

Take a look at NSFetchRequest's setIncludesSubentities method. If your data model reflects your inheritance pattern in your code, then your fetch request won't fetch children entities if you've set it properly.

NSFetchRequest *request = [[NSFetchRequest alloc] init]; request.includesSubentities = NO;