核心数据NSValidationErrorObject，导致崩溃

Question

我正在开发一个应用程序，我有用户，每个用户都有跟随者的多对多关系。我目前在保存新用户对象时遇到了一些问题。该应用程序在managedObjectContext save上分割。我收到以下错误：

Unresolved error Error Domain=NSCocoaErrorDomain Code=1560 "The operation couldn’t be completed. (Cocoa error 1560.)" UserInfo=0x8580640 {NSDetailedErrors=(
"Error Domain=NSCocoaErrorDomain Code=1550 \"The operation couldn\U2019t be completed. (Cocoa error 1550.)\" UserInfo=0x85820c0 {NSValidationErrorObject=<User: 0x7575870> (entity: User; id: 0x75757c0 

NSValidationErrorKey=followers, NSLocalizedDescription=The operation couldn\U2019t be completed. (Cocoa error 1550.), NSValidationErrorValue=Relationship 'followers' on managed object (0x7575870) <User: 0x7575870> (entity: User; id: 0x75757c0 
"Error Domain=NSCocoaErrorDomain Code=1550 \"The operation couldn\U2019t be completed. (Cocoa error 1550.)\" UserInfo=0x8586830 {NSValidationErrorObject=<User: 0x7571ec0> (entity: User; id: 0x7571f00 

"Error Domain=NSCocoaErrorDomain Code=1550 \"The operation couldn\U2019t be completed. (Cocoa error 1550.)\" UserInfo=0x858e820 {NSValidationErrorObject=<User: 0x7573120> (entity: User; id: 0x7573160 

[...] 

我无法真正弄清楚是什么导致了这个崩溃。我的关系是这样的：

该模型有一个自定义NSManagedObject子类与@property (nonatomic, retain) NSSet *followers;。正如我所说，我不确定是什么造成了这一点，所以任何指导或想法都会很棒！

更新

该方法的应用程序崩溃：

- (void)saveContext 
{ 
    NSError *error = nil; 
    NSManagedObjectContext *managedObjectContext = self.managedObjectContext; 
    [managedObjectContext setMergePolicy:NSMergeByPropertyObjectTrumpMergePolicy]; 
    if (managedObjectContext != nil) { 
     if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) { 
      // Replace this implementation with code to handle the error appropriately. 
      // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. 
      NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
      // Uncomment "abort" makes it work, but I still get the error. 
      abort(); 
     } 
    } 
} 

更新2

更多来自我的模型代码，以及如何使用它们：

如何我设置我的获取请求控制器：

- (NSSortDescriptor *)sortDescriptorForFetchRequest 
{ 
    NSSortDescriptor *sortDescriptor; 
    if ([self.postType isEqualToString:@"following"] || [self.postType isEqualToString:@"followers"]) { 
     sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"userId" ascending:NO]; 
    } else { 
     sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"postId" ascending:NO]; 
    } 

    return sortDescriptor; 
} 

- (NSEntityDescription *)entityForFetchRequest 
{ 
    NSEntityDescription *entity; 
    if ([self.postType isEqualToString:@"followers"] || [self.postType isEqualToString:@"following"]) { 
     entity = [NSEntityDescription entityForName:@"User" inManagedObjectContext:[self.appController managedObjectContext]]; 
    } else { 
     entity = [NSEntityDescription entityForName:@"Post" inManagedObjectContext:[self.appController managedObjectContext]]; 
     } 

    return entity; 
} 

- (void)setUpFetchResultController 
{ 
    if (self.fetchedResultsController == nil) { 
     NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; 
     [fetchRequest setEntity:[self entityForFetchRequest]]; 
     [fetchRequest setPredicate:[self predicateBasedOnPostType:self.postType]]; 
     NSArray *sortDescriptors = @[[self sortDescriptorForFetchRequest]]; 
     [fetchRequest setSortDescriptors:sortDescriptors]; 

     self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:[self.appController managedObjectContext] sectionNameKeyPath:nil cacheName:[self cacheName]]; 
     self.fetchedResultsController.delegate = self; 
    } 
} 

而且我的模型，User：

+ (void)addUserFromDictionary:(NSDictionary *)dictionary forUser:(User *)user inManagedObjectContext:(NSManagedObjectContext*)moc follower:(BOOL)follower following: (BOOL)following 
{ 
    User *localUser; 
    if (follower) { 
     if ([dictionary isKindOfClass:[NSArray class]]) { 
      NSEnumerator *enumerator = [dictionary objectEnumerator]; 
      id value; 
      while (value = [enumerator nextObject]) { 
       localUser = [self parseUserFromDictionary:value inManagedObjectContext:moc]; 

       if ([self user:localUser alreadyFollowingUser:user inManagedObjectContext:moc] == NO) { 
        [user addFollowersObject:localUser]; 
        [localUser addFollowingObject:user]; 
       } 
      } 
     } 
    } 
} 

+ (User *)parseUserFromDictionary:(NSDictionary *)dictionary inManagedObjectContext:(NSManagedObjectContext*)moc 
{ 
    NSNumberFormatter *numberFormatter= [[NSNumberFormatter alloc] init]; 
    NSNumber * userId = [numberFormatter numberFromString:(NSString *)[dictionary valueForKey:@"id"]]; 

    User *user; 

    if ([self userAlreadyExist:userId inManagedObjectContext:moc] == NO) { 
     NSEntityDescription *userDescription = [NSEntityDescription entityForName:@"User" inManagedObjectContext:moc]; 
     user = [[User alloc] initWithEntity:userDescription insertIntoManagedObjectContext:moc]; 
    } else { 
     user = [User findUser:userId inManagedObjectContext:moc]; 
    } 

    user.name = [dictionary valueForKey:@"name"]; 
    [...]  
    return user; 
} 

Answer 1

在预感：不同的MOC中的对象之间的关系？奇怪的事情可能发生，如果你这样做！

Answer 2

将是有益的，如果你给的模型定义的详细信息，包括User和Followers。这是一个猜测，但followers不正确吗？

我希望看到在用户的关系定义如下：

M followers User following 

和追随者的关系定义如下：

M following User followers 

Answer 3

我复制你的代码和数据模型在一个单独的项目。我认为这可能是你的数据什么的一个周期，所以我尝试了所有的如下代码：

[userA addFollowersObject:userB]; 
[userB addFollowingObject:userA]; 

[userB addFollowersObject:userA]; 
[userA addFollowingObject:userB]; 

[userA addFollowersObject:userA]; 
[userA addFollowingObject:userA]; 

[userB addFollowingObject:userB]; 
[userB addFollowersObject:userB]; 

...但节省是有效的所有时间。我能想到的最后一件事是多线程。你是否正在使用多个线程访问ManagedObjectContext？如果是这样，那可能会导致导致错误的数据不一致。