Question

我的核心数据对象如下：

作者（姓名）＆gt;＆gt;书（标题）＆gt;＆gt;备注（text，dateOfNote）

关系boksByAuthor＆gt;＆gt; notesOnBook

+(void)persistBooksToDisk:(NSManagedObjectContext *)workerContext
                 subClass:(EECoreStack*)eeCoreStack
                  fromURL:(NSURL*)fileURL{
[workerContext performBlock:^{
        NSArray * array = [AP_TextExtract componentSeperatedByBooksFromTXTFile:fileURL];
        for (NSString *body in array) {
Note *note = (Note *) [NSEntityDescription insertNewObjectForEntityForName:@"Note" inManagedObjectContext:workerContext];

note.dateOfNote = [AP_TextExtract dateOfNoteFromString:body];
note.text = [AP_TextExtract noteTextFromString:body];

 Book *book = (Book *) [NSEntityDescription insertNewObjectForEntityForName:@"Book" inManagedObjectContext:workerContext];
            book.title = [AP_TextExtract bookNameFromString:body];
[book addNotesInBook: note];
  Author *author = (Author*)[NSEntityDescription insertNewObjectForEntityForName:@"Author" inManagedObjectContext:workerContext];
            author.name = [AP_TextExtract authorNameFromString:body];
[author addBooksByAuthor: book];
}];

[eeCoreStack saveTemporaryWorkerContext:workerContext];
}

saveTemporaryContext：

- (void)saveTemporaryWorkerContext:(NSManagedObjectContext *)context {
[context performBlock:^{
    NSError *error;
    [context save:&error];
    if (error) {
        NSLog(@"ERROR SAVING TEMPORARY WORKER MOC %@:  %@:", [error localizedDescription], [error userInfo]);
    }else {

        [self saveMainContext];
    }

}];
}

- (void)saveMainContext {
    [self.mainContext performBlock:^{
        NSError *error = nil;
        [self.mainContext save:&error];
        if(error){
            NSLog(@"ERROR SAVING MAIN MOC %@: %@:", [error localizedDescription], [error userInfo]);
        }else {
            [self saveMasterContext];
        }
    }];
}

- (void)saveMasterContext {

    [self.masterContext performBlock:^{
        NSError *error = nil;
        [self.masterContext save:&error];
        if(error){
            NSLog(@"ERROR SAVING MASTER CONTEXT %@; : %@", [error localizedDescription], [error userInfo]);
        }
    }];
    [[NSNotificationCenter defaultCenter] postNotificationName:@"doneSavingMasterContext" object:nil];

}

数据从文本文件中保存，保存遵循模式：

workerContext＆gt; mainContext＆gt; masterContext（商店）

第一次成功保存数据但稍后当它尝试保存更新的文本文件（只更改注释文本）时，会抛出以下错误：

ERROR SAVING MASTER CONTEXT保存时发生错误。

; : {   
 NSAffectedObjectsErrorKey =     (
            "<Note: 0x6000002d6570> (entity: Note; id: 0x600001424480 <x-coredata:///Note/t2371834C-1581-4A68-A56E-77E734B276CC1244> ; data:
    text = \"quitely right );
        NSUnderlyingException = "Cannot update object that was never inserted.";
    }

有一件事我注意到，重新启动应用后，数据会被保存，但之后会再次开始提供相同的错误。

编辑1：此错误仅显示我是否更新现有属性，如果我插入新属性实例则不显示。

Answer 1

更新数据时，首先使用NSFetchRequest获取核心数据对象，然后更新必要的数据。然后尝试保存。您可能尝试在不提取的情况下更新数据。

更新存储时，我收到以下错误：NSUnderlyingException =“无法更新从未插入的对象。”

1 个答案: