如何使用MVVM将焦点设置为WPF控件？

我正在validation我的viewmodel中的用户输入并抛出validation消息，以防任何值的validation失败。

我只需要将焦点设置为validation失败的特定控件。

知道怎么做到这一点？

Answer 1

通常，当我们想要在遵守MVVM方法的同时使用UI事件时，我们会创建一个Attached Property ：

 public static DependencyProperty IsFocusedProperty = DependencyProperty.RegisterAttached("IsFocused", typeof(bool), typeof(TextBoxProperties), new UIPropertyMetadata(false, OnIsFocusedChanged)); public static bool GetIsFocused(DependencyObject dependencyObject) { return (bool)dependencyObject.GetValue(IsFocusedProperty); } public static void SetIsFocused(DependencyObject dependencyObject, bool value) { dependencyObject.SetValue(IsFocusedProperty, value); } public static void OnIsFocusedChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs) { TextBox textBox = dependencyObject as TextBox; bool newValue = (bool)dependencyPropertyChangedEventArgs.NewValue; bool oldValue = (bool)dependencyPropertyChangedEventArgs.OldValue; if (newValue && !oldValue && !textBox.IsFocused) textBox.Focus(); } 

此属性使用如下：

然后我们可以通过将IsFocused属性更改为true来从视图模型中聚焦TextBox ：

 IsFocused = false; // You may need to set it to false first if it is already true IsFocused = true;