I have the following code which seems to go on indefinitely until the app crashes. It seems to happen with the recursion in the datastructureFromManagedObject method. I suspect that this method:

1) looks at the first managed object and follows any relationship property recursively. 2) examines the object at the other end of the relationship found at point 1 and repeats the process.

Is it possible that if managed object A has a to-many relationship with object B and that relationship is two-way (i.e an inverse to-one relationship to A from B - e.g. one department has many employees but each employee has only one department) that the following code gets stuck in infinite recursion as it follows the to-one relationship from object B back to object A and so on.

If so, can anyone provide a fix for this so that I can get my whole object graph of managed objects converted to JSON.

#import "JSONUtils.h"


@implementation JSONUtils

- (NSDictionary*)dataStructureFromManagedObject:(NSManagedObject *)managedObject {

    NSDictionary *attributesByName = [[managedObject entity] attributesByName];
    NSDictionary *relationshipsByName = [[managedObject entity] relationshipsByName];

    //getting the values correspoinding to the attributes collected in attributesByName
    NSMutableDictionary *valuesDictionary = [[managedObject dictionaryWithValuesForKeys:[attributesByName allKeys]] mutableCopy];

    //sets the name for the entity being encoded to JSON
    [valuesDictionary setObject:[[managedObject entity] name] forKey:@"ManagedObjectName"];

    NSLog(@"+++++++++++++++++> before the for loop");
    //looks at each relationship for the given managed object
    for (NSString *relationshipName in [relationshipsByName allKeys]) {
        NSLog(@"The relationship name = %@",relationshipName);
        NSRelationshipDescription *description = [relationshipsByName objectForKey:relationshipName];

        if (![description isToMany]) {
            NSLog(@"The relationship is NOT TO MANY!");
            [valuesDictionary setObject:[self dataStructureFromManagedObject:[managedObject valueForKey:relationshipName]] forKey:relationshipName];
            continue;
        }
        NSSet *relationshipObjects = [managedObject valueForKey:relationshipName];
        NSMutableArray *relationshipArray = [[NSMutableArray alloc] init];
        for (NSManagedObject *relationshipObject in relationshipObjects) {
            [relationshipArray addObject:[self dataStructureFromManagedObject:relationshipObject]];
        }
        [valuesDictionary setObject:relationshipArray forKey:relationshipName];
    }
    return [valuesDictionary autorelease];
}

- (NSArray*)dataStructuresFromManagedObjects:(NSArray*)managedObjects {

    NSMutableArray *dataArray = [[NSArray alloc] init];
    for (NSManagedObject *managedObject in managedObjects) {
        [dataArray addObject:[self dataStructureFromManagedObject:managedObject]];
    }
    return [dataArray autorelease];
}


//method to call for obtaining JSON structure - i.e. public interface to this class
- (NSString*)jsonStructureFromManagedObjects:(NSArray*)managedObjects {
    NSLog(@"-------------> just before running the recursive method");
    NSArray *objectsArray = [self dataStructuresFromManagedObjects:managedObjects];
    NSLog(@"-------------> just before running the serialiser");
    NSString *jsonString = [[CJSONSerializer serializer] serializeArray:objectsArray];
    return jsonString;
}

- (NSManagedObject*)managedObjectFromStructure:(NSDictionary*)structureDictionary withManagedObjectContext:(NSManagedObjectContext*)moc {

    NSString *objectName = [structureDictionary objectForKey:@"ManagedObjectName"];
    NSManagedObject *managedObject = [NSEntityDescription insertNewObjectForEntityForName:objectName inManagedObjectContext:moc];
    [managedObject setValuesForKeysWithDictionary:structureDictionary];

    for (NSString *relationshipName in [[[managedObject entity] relationshipsByName] allKeys]) {
        NSRelationshipDescription *description = [[[managedObject entity]relationshipsByName] objectForKey:relationshipName];
        if (![description isToMany]) {
            NSDictionary *childStructureDictionary = [structureDictionary objectForKey:relationshipName];
            NSManagedObject *childObject = [self managedObjectFromStructure:childStructureDictionary withManagedObjectContext:moc];
            [managedObject setValue:childObject forKey:relationshipName];
            continue;
        }
        NSMutableSet *relationshipSet = [managedObject mutableSetValueForKey:relationshipName];
        NSArray *relationshipArray = [structureDictionary objectForKey:relationshipName];
        for (NSDictionary *childStructureDictionary in relationshipArray) {
            NSManagedObject *childObject = [self managedObjectFromStructure:childStructureDictionary withManagedObjectContext:moc];
            [relationshipSet addObject:childObject];
        }
    }
    return managedObject;
}

//method to call for obtaining managed objects from JSON structure - i.e. public interface to this class
- (NSArray*)managedObjectsFromJSONStructure:(NSString *)json withManagedObjectContext:(NSManagedObjectContext*)moc {

    NSError *error = nil;
    NSArray *structureArray = [[CJSONDeserializer deserializer] 
                               deserializeAsArray:[json dataUsingEncoding:NSUTF32BigEndianStringEncoding] 
                               error:&error];

    NSAssert2(error == nil, @"Failed to deserialize\n%@\n%@", [error localizedDescription], json);
    NSMutableArray *objectArray = [[NSMutableArray alloc] init];

    for (NSDictionary *structureDictionary in structureArray) {
        [objectArray addObject:[self managedObjectFromStructure:structureDictionary withManagedObjectContext:moc]];
    }
    return [objectArray autorelease];
}


@end