Question

所以我正在使用CoreData做申请表首先，我要创造＆＃34; Shop＆＃34;具有唯一名称和一些属性。在应用程序中，您可以编辑＆＃34; Shop＆＃34;，然后我尝试通过＆＃34; shopName＆＃34;进行验证。避免创作另一个＆＃34; Shop＆＃34;同名。我用这个：

    -(BOOL)uniqueEntityExistsWithEnityName {

    BOOL returnValue = NO;

    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Shop"];

    NSPredicate* predicate = [NSPredicate predicateWithFormat:@"shopName = [cd] %@", _shopName.text];

    NSSortDescriptor *shop = [[NSSortDescriptor alloc] initWithKey:@"shopName" ascending:YES];

    [request setSortDescriptors: @[shop]];
    [request setPredicate:predicate];

    NSError *error = nil;
    NSArray *matches = [self.managedObjectContext executeFetchRequest:request error:&error];

    NSLog(@"request = %@",predicate);

    if (!matches) {
        NSLog(@"Error: Couldn't execute fetch request %@", error);

    }
    else if([matches count] > 1) {

        NSString *existShop = [NSString stringWithFormat:@"Could Be Only One %@ Shop", _shopName.text];

        UIAlertView *exist = [[UIAlertView alloc]initWithTitle:@"Shop Exists in Your Records"
                                                       message:existShop
                                                      delegate:nil
                                             cancelButtonTitle:@"Ok"
                                             otherButtonTitles:nil];
        [exist show];

        NSLog(@"Error: Have more than %lu records",
              (unsigned long)[matches count]);
        returnValue = YES;
    }
    else {

        NSLog(@"%lu object in record", (unsigned long)[matches count]);

        [self oldShopDelete];
        [self checkShopPhoneNumber];

        editShop.shopName = _shopName.text;
        editShop.shopPhoneNumber = _shopPhoneNumber.text;
        editShop.shopSecondPhoneNumber = _shopSecondPhoneNumber.text;
        editShop.shopEmail = _shopEmail.text;
        editShop.shopNote = _shopNoteView.text;

        [super saveAndDissmiss];

        returnValue = YES;
    }
    return returnValue;
}

使用该代码，您仍然有机会再保存一个已编辑的＆＃34; Shop＆＃34;同名。但问题是 - 在此之后我无法制作[matches count] = 1我将无法编辑该商店

也许有另一种方法可以进行此类验证？

Answer 1

仅在首次实际设置名称或编辑名称时检查名称冲突。

您还可以将当前商店传递到谓词中以确保AND SELF != %@，这样就不会与正在编辑但名称未更改的现有商店匹配。

coreData现有验证

1 个答案: