在向用户呈现验证错误之前创建一个延迟 [英] Create a delay before validation errors are presented to the user

问题描述

在遵循MVVM模式的特定WPF应用程序中，视图模型实现IDataErrorInfo接口，以在文本字段中通知无效数据视图。

In this specific WPF application which follows the MVVM pattern, the view model implements the IDataErrorInfo interface to notify the view of invalid data in text fields.

文本框存在于您可以输入体积的视图中。这是通过属性更改的更新源指定的，并验证数据错误：

A text box exists in the view where you can enter a volume. This has been specified with property changed update source, and validate data errors:

<TextBox 
    Text="{Binding Volume, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}" />

此问题是您在用户完成输入之前收到验证错误。例如，有效值为 25 ml。但是在用户键入最后一个 l之前，文本框中将出现 25 m。这不是有效值，将导致IDataError实现这样说。

The problem with this is that you get a validation error before the user has finished typing. E.g., a valid value is "25 ml". But before the user has typed in the last "l", then "25 m" is present in the text box. This is not a valid value and will result in the IDataError implementation saying so.

结果是，随着用户的输入，红色标记在文本框周围闪烁。

The result is, as the user is typing, a red marker flashes around the text box.

我们希望在文本框周围的红色标记出现之前有一点延迟（0.5秒），因此我们可以假设用户在完成验证之前已经完成了键入操作错误。

We would like to have a little delay (0.5 sec) before the red marker appears around the text box, so we can assume that the user has finished typing before showing validation errors.

第一次尝试是创建一个专用的文本框，该框等待0.5秒后再更新视图模型中的属性。但这不好，因为在用户确实输入有效值的情况下，则在启用提交按钮之前0.5秒过去了。

The first attempt was to create a specialized text box that waits .5 sec before updating the property in the view model. But that is no good, because in the case that the user does enter a valid value, then .5 second passes before the submit button gets enabled.

我有个主意您可以编写实现此行为的专用绑定（即创建派生自System.Windows.Data.Binding的专用类），但我不知道如何执行此操作。

I have an idea that you could write a specialized binding (i.e. create a specialized class derived from System.Windows.Data.Binding) that implements this behavior, but I have no idea how to do this.

这是一个合理的方法，还是有更好的方法？

Is that a plausible way, or is there a better?

推荐答案

听起来像您可以使用Paul的自定义DelayBinding Stovell发表了关于。我成功实施了延迟搜索/过滤功能，并成功使用了它。您可以在此处阅读以下内容：

Sounds like you could use a custom DelayBinding that Paul Stovell blogged about. I've used it with great success implementing delayed search/filtering. You can read about it here:

http：/ /www.paulstovell.com/wpf-delaybinding

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