在WPF，MVVM中实现TextBox LostFocus事件

本文介绍了在WPF，MVVM中实现TextBox LostFocus事件的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我想在我的WPF窗口中实现TextBox LostFocus事件，该事件应该在我的ViewModel中触发，以便我可以验证该值。偶数参数应该传递给命令。如果我们可以使用附加命令行为，那么任何人都可以请分享一个例子。 注意：我使用的是MVVM模式。 问候， Ramana

I want to implement TextBox LostFocus event in my WPF window which should be fired in my ViewModel so that I can validate the value. Even parameter should be passed to the command. If we can use Attached Command Behavior, so anyone can please share an example. Note: I am using MVVM pattern. Regards, Ramana

推荐答案

可以通过创建的附加行为来实现。 Can be achieved by created Attached Behaviour. public class TextBoxBehavior { public static DependencyProperty OnLostFocusProperty = DependencyProperty.RegisterAttached( "OnLostFocus", typeof(ICommand), typeof(TextBoxBehavior), new UIPropertyMetadata(TextBoxBehavior.OnLostFocus)); public static void SetOnLostFocus(DependencyObject target, ICommand value) { target.SetValue(TextBoxBehavior.OnLostFocusProperty, value); } /// <summary> /// PropertyChanged callback for OnDoubleClickProperty. Hooks up an event handler with the /// actual target. /// </summary> private static void OnLostFocus(DependencyObject target, DependencyPropertyChangedEventArgs e) { var element = target as TextBox; if (element == null) { throw new InvalidOperationException("This behavior can be attached to a TextBox item only."); } if ((e.NewValue != null) && (e.OldValue == null)) { element.LostFocus += OnPreviewLostFocus; } else if ((e.NewValue == null) && (e.OldValue != null)) { element.LostFocus -= OnPreviewLostFocus; } } private static void OnPreviewLostFocus(object sender, RoutedEventArgs e) { UIElement element = (UIElement)sender; ICommand command = (ICommand)element.GetValue(TextBoxBehavior.OnLostFocusProperty); if (command != null) { command.Execute(e); } } }

xmlns:ACB="clr-namespace:XML_Binding_Sample1.AttachedCommandBehaviour" <textbox text="{Binding CustomerName}" acb:textboxbehavior.onlostfocus="{Binding NameChangeCommand}" xmlns:acb="#unknown" />