发生DBupdateException时为用户显示用户友好错误消息的最佳方法 [英] Best Way to display a user friendly error message for the users, when an DBupdateexception occurred

问题描述

我的操作方法中包含以下代码：

I have the following code inside my action method :

Try {
    repository.Save();
    DetailBox b = new DetailBox() { 
        Tag = repository.getTechnologyTagByIT360ID(resourceid) 
    };

    return PartialView("_detailBox", b);
}
catch (DbUpdateException e)
{
    ModelState.AddModelError(string.Empty, "Error occurred:" +
        e.InnerException.InnerException.Message);
}

当前，如果发生DbUpdatException，它将向用户显示以下错误：

Currently, if the DbUpdatException occurs it will show the following error to the user:

•发生错误：违反UNIQUE KEY约束'IX_Technology_2'。
无法在对象dbo.Technology中插入重复的密钥。
的重复键值为（18605）。该语句已终止。

• Error occurred: Violation of UNIQUE KEY constraint 'IX_Technology_2'. Cannot insert duplicate key in object 'dbo.Technology'. The duplicate key value is (18605). The statement has been terminated.

虽然不是很糟糕，但是同时它也不是很友好。现在，有很多原因可能导致DbUpateException发生，因此我无法定义自己的message。那么，我应该采取哪种方法呢？例如，我是否应该编写一种服务方法来检查 repository.Save（）; 之前数据库中是否存在重复的键值（18605）？

Which is not very bad, but at the same time, it is not very user friendly. Now there are many reasons why the DbUpateException might occur, so I can not define my own message . So, which approach should I take? Should I, for example, write a service method that check if the duplicate key value (18605) already exists in the database just before the repository.Save();?

推荐答案

捕获异常是您处理意外情况的方法，通常是在与就像文件系统，服务和数据库一样，是您无法控制的。

Catching exceptions is something you do to deal with unexpected situations, typically when interacting with systems that are beyond your own control, like file systems, services and yes, databases.

但是例外应该是例外。也就是说，只要可以预见到它们，就应该尝试防止它们被抛出。绝对不要将它们用于程序流控制。因此，如果用户可以输入重复的数据库条目，请先检查并在违反约束时返回一个体面的消息。这是对用户输入进行常规验证的一部分。就像您不允许在数据库字段的字符串值太长时发生异常一样。

But exceptions should be that - exceptional. That is, whenever you can anticipate them you should try to prevent them from being thrown. You should never use them for program flow control. So if a user can enter duplicate database entries, check first and return a decent message when the constraint is violated. It's part of normal validation of user input. Same as you don't allow an exception to occur when a string value is too long for a database field.

最后的捕获仍然应该存在，但是现在确实如此变为 exception ，即在检查和提交之间的极短时间内，并发用户碰巧输入了相同的值。

The final catch should still be there, but now it really becomes exceptional, that is, when the same value happens to get entered by a concurrent user in the tiny time lapse between the check and the commit.

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