Coredata错误“数据：< fault> [英] Coredata Error "data: <fault>"

问题描述

我尝试使用以下代码从CoreData中提取数据

I try to pull out data from CoreData with the following code

NSFetchRequest *request = [[NSFetchRequest alloc] init];
request.entity = [NSEntityDescription entityForName:@"Cave" inManagedObjectContext:self.context];
request.predicate = [NSPredicate predicateWithFormat:@"(latitude > 0) AND (longitude > 0)"];

NSError *error;
NSLog(@"%@",[self.context executeFetchRequest:request error:&error]);
NSLog(@"%@",[error localizedDescription]);

CoreData应该有9个匹配对象，它找到9个对象。所以谓词应该工作，但我在控制台中得到这个

CoreData should have 9 matching objects and it finds the 9 objects. So the predicate should work but I get this in the console

2011-09-05 07:41:42.267 CaveConditions[6930:11903] (
    "<NSManagedObject: 0x7368060> (entity: Cave; id: 0x7367880 <x-coredata://C825FC9D-3490-4D8A-A811-979B819A2EB6/Cave/p31> ; data: <fault>)",
    "<NSManagedObject: 0x73547e0> (entity: Cave; id: 0x7356e20 <x-coredata://C825FC9D-3490-4D8A-A811-979B819A2EB6/Cave/p40> ; data: <fault>)",
    "<NSManagedObject: 0x73681e0> (entity: Cave; id: 0x7363e60 <x-coredata://C825FC9D-3490-4D8A-A811-979B819A2EB6/Cave/p42> ; data: <fault>)",
    "<NSManagedObject: 0x7368280> (entity: Cave; id: 0x7356be0 <x-coredata://C825FC9D-3490-4D8A-A811-979B819A2EB6/Cave/p72> ; data: <fault>)",
    "<NSManagedObject: 0x7368320> (entity: Cave; id: 0x733ad80 <x-coredata://C825FC9D-3490-4D8A-A811-979B819A2EB6/Cave/p73> ; data: <fault>)",
    "<NSManagedObject: 0x73683c0> (entity: Cave; id: 0x7333e70 <x-coredata://C825FC9D-3490-4D8A-A811-979B819A2EB6/Cave/p91> ; data: <fault>)",
    "<NSManagedObject: 0x7368480> (entity: Cave; id: 0x7361810 <x-coredata://C825FC9D-3490-4D8A-A811-979B819A2EB6/Cave/p101> ; data: <fault>)",
    "<NSManagedObject: 0x7368570> (entity: Cave; id: 0x7360110 <x-coredata://C825FC9D-3490-4D8A-A811-979B819A2EB6/Cave/p105> ; data: <fault>)",
    "<NSManagedObject: 0x7368610> (entity: Cave; id: 0x73303c0 <x-coredata://C825FC9D-3490-4D8A-A811-979B819A2EB6/Cave/p112> ; data: <fault>)"
)

它用于完美地工作，直到我在Cave.m中进行了以下更改，即Entity

It used to work prefectly fine until I did the following change in Cave.m which is the Entity

我在Cave.h中添加了MKAnnotation作为委托，并在Cave.m中添加了这个代码。

I added MKAnnotation as a delegate in Cave.h and added this code in Cave.m

- (CLLocationCoordinate2D)coordinate
{
    CLLocationCoordinate2D location;
    location.latitude = [self.latitude doubleValue];
    location.longitude = [self.longitude doubleValue];
    return location;
}

有没有办法调试这个？

推荐答案

这是预期的行为，核心数据将不会返回完整的对象，直到你需要访问对象的持久值。

This is expected behaviour, core data won't return full objects until you need to access the persistent values of the objects. Each of your returned objects will be a 'fault' until this point.

您可以使用 [request setReturnsObjectsAsFaults：NO]强制获取请求返回完整的对象。 / code>，但在大多数情况下你会有好的。有关更多信息，请参阅NSFetchRequest的文档。

You can force the fetch request to return full objects using [request setReturnsObjectsAsFaults:NO], but in most cases what you have will be fine. Look at the documentation for NSFetchRequest for more information.

如果您访问其中一个属性，核心数据将转到持久存储并获取其余值，然后您将在日志中获得完整描述。

If you access one of the properties, core data will go to the persistent store and fetch the rest of your values, then you'll get the full description in the logs.

这似乎是一个常见的误解，我决定写一下，这里。

This seems to be such a common misunderstanding that I decided to write about it, here.

这篇关于Coredata错误“数据：< fault>的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！