【问题标题】:Core Data not firing fault for entity properties but does for relationshipsCore Data 不会触发实体属性的错误,但会触发关系
【发布时间】:2016-03-01 18:57:23
【问题描述】:

我有一个名为 Trigger 的核心数据实体,它与另一个名为 ActiveTrigger 的实体具有多对一的关系。当我使用[request setReturnsObjectsAsFaults:NO]; 查询触发器对象的核心数据时,查询结果在每个触发器上都有一个 ActiveTrigger 实体的 NSSet,即 trigger.activeTriggers。然而,ActiveTrigger 对象有一个数据错误,当我访问任何属性时不会触发该错误,但当我访问 ActiveTrigger 上的关系之一时会触发。访问属性或关系时不应该触发故障吗?使用关系触发故障后,未触发故障返回后返回的相同属性(null)为实际值。

NSFetchRequest * request = [NSFetchRequest fetchRequestWithEntityName:NSStringFromClass([Trigger class])];
[request setPredicate:[NSPredicate predicateWithFormat:@"identifier IN %@", triggerIds]];
[request setReturnsObjectsAsFaults:NO];

NSError * error = nil;
NSArray * results = [[NSManagedObjectContext sharedManagedObjectContext] executeFetchRequest:request error:&error];
for (Trigger * trigger in results) {
    for (ActiveTrigger * activeTrigger in trigger.activeTriggers) {
        NSLog(@"Here is the survey name as a property on the ActiveTrigger 1:  %@", activeTrigger.surveyName);
        NSLog(@"Here is the survey name via the relationship:                  %@", activeTrigger.survey.name);
        NSLog(@"Here is the survey name as a property on the ActiveTrigger 2:  %@", activeTrigger.surveyName);
    }
}


//Here are the logs resulting from the code above
2016-03-01 13:48:28.809 AppName[31787:1480404] Here is the survey name as a property on the ActiveTrigger 1:  (null)
2016-03-01 13:48:28.811 AppName[31787:1480404] Here is the survey name via the relationship:                  All Q
2016-03-01 13:48:28.811 AppName[31787:1480404] Here is the survey name as a property on the ActiveTrigger 2:  All Q

第一个日志后的断点确认activeTrigger对象在尝试访问surveyName属性后仍有数据故障

【问题讨论】:

    标签: ios objective-c core-data


    【解决方案1】:

    解决了。事实证明,ActiveTrigger 实现中的属性使用@synthesize 而不是@dynamic。更改为动态,访问属性时正确触发数据错误

    【讨论】:

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