objective-c - 删除核心数据对象不会取消其所有关系吗？

Question

我有一个名为 Task 的实体，它与实体 TaskTemplate 和 Occurrence 具有一对一关系。这两个实体都与任务有一对多关系。删除规则设置为无效。

在一次事件中，我尝试删除所有任务。为此，我使用以下代码:

- (bool)removeAllTasks
{
    NSMutableSet *tasks = [self mutableSetValueForKey:@"tasks"];
    [tasks removeAllObjects];
    return YES;
}

这不起作用。以下是尝试删除之前的任务和发生情况:

Relationship 'tasks' on managed object (0x1006bd1c0) <Occurrence: 0x1006bd1c0> (entity: Occurrence; id: 0x102119510 <x-coredata://6A0ECEF9-473D-44B2-9E89-AC15179D7761/Occurrence/p1> ; data: {
    ... bunch of properties ...
    taskType = "0x10211a020 <x-coredata://6A0ECEF9-473D-44B2-9E89-AC15179D7761/TaskTemplate/p2>";
    tasks =     (
        "0x1021185e0 <x-coredata://6A0ECEF9-473D-44B2-9E89-AC15179D7761/Task/p3>"
    );
}) with objects {(
    <Task: 0x10c31d700> (entity: Task; id: 0x1021185e0 <x-coredata://6A0ECEF9-473D-44B2-9E89-AC15179D7761/Task/p3> ; data: {
    ... some more properties ...
    occurrence = "0x102119510 <x-coredata://6A0ECEF9-473D-44B2-9E89-AC15179D7761/Occurrence/p1>";
    persons = "<relationship fault: 0x10e049e90 'persons'>";
    startDate = "2013-01-28 11:00:00 +0000";
    type = "0x10211a020 <x-coredata://6A0ECEF9-473D-44B2-9E89-AC15179D7761/TaskTemplate/p2>";
})
)}

...这是 -removeAllObjects 之后的结果:

Relationship 'tasks' on managed object (0x1006bd1c0) <Occurrence: 0x1006bd1c0> (entity: Occurrence; id: 0x102119510 <x-coredata://6A0ECEF9-473D-44B2-9E89-AC15179D7761/Occurrence/p1> ; data: {
    ... bunch of properties ...
    taskType = "0x10211a020 <x-coredata://6A0ECEF9-473D-44B2-9E89-AC15179D7761/TaskTemplate/p2>";
    tasks =     (
    );
}) with objects {(
)}

请注意，任务关系现在为空，正如我所期望的那样。但我也希望 taskType 为空。我做错了什么？

编辑:

我更改了代码，以便可以查看任务是否被标记为已删除。我现在有:

- (bool)removeAllEvents
{
    NSMutableSet *tasks = [self mutableSetValueForKey:@"tasks"];
    [tasks enumerateObjectsUsingBlock:^(Task *task, BOOL *stop)
     {
    if (![task isDeleted])
         [self.managedObjectContext deleteObject:task];
         NSLog(@"Deleted %@", [task isDeleted] ? @"Y" : @"N");
     }];
    [self.managedObjectContext processPendingChanges];
    return YES;
}

它确实显示“Y”，表示该任务已标记为删除。 fetchRequest 向我显示上下文中没有剩余任务。但如果我尝试保存，我会收到不一致的消息(“任务无效”)。

Answer 1

您的removeAllTask​​s方法不会删除任何对象。它仅删除 Occurrence 对象与 Task 对象的关系，但任务仍然存在。仅当删除对象时(使用 deleteObject:)才应用删除规则。