wpf - 如何在WPF(MVVM)中收到对控件的引用？

Question

在我的WPF MVVM项目中，我有一个按钮，该按钮触发一个函数，该函数应将节点添加到xml，然后将焦点设置为文本框。
我的问题是，我如何获得对控件的引用？

看法:

<Button Command="{Binding Path=ButtonAddCategory_Click}" />

ViewModel:

RelayCommand buttonAddCategory_Click;
public ICommand ButtonAddCategory_Click
{
    get
    {
        return buttonAddCategory_Click ?? (buttonAddCategory_Click = new RelayCommand(param => this.AddCategory(),
                                                                                      param => true));
    }
}

public void AddCategory()
{
    ...
    //get the "node" -> reference?
    XmlNode selectedItem = (XmlNode)treeView.SelectedItem;
    ..
    //add the node to the xml
    ..
    //change focus -> reference?
    textBoxTitel.Focus();
    textBoxTitel.SelectAll();
}

Answer 1

不要在ViewModel中执行此操作。 ViewModel应该对 View 一无所知。

您可以在代码隐藏中进行操作:

在代码隐藏中处理TreeView.SelectedItemChanged事件，并更新ViewModel上的SelectedItem属性(也可以通过附加行为来完成)

集中TextBox，从ViewModel引发一个事件，并在后台代码中处理它:

ViewModel:

public XmlNode SelectedItem { get; set; }

public event EventHandler FocusTitle;

public void AddCategory()
{
    ...
    //get the "node" -> reference?
    XmlNode selectedItem = this.SelectedItem;
    ..
    //add the node to the xml
    ..
    // Notify the view to focus the TextBox
    if (FocusTitle != null)
        FocusTitle(this, EventArgs.Empty);

}

背后的代码:

// ctor
public MyView()
{
    InitializeComponent();
    DataContextChanged += MyView_DataContextChanged;
}

private void MyView_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
{
    MyViewModel vm = (MyViewModel)e.NewValue;
    vm.FocusTitle += ViewModel_FocusTitle;
}

private void TreeView1_SelectedItemChanged(object sender, RoutedPropertyChangedEventHandler<Object> e)
{
    MyViewModel vm = (MyViewModel)DataContext;
    vm.SelectedItem = (XmlNode)e.NewValue;
}

private void ViewModel_FocusTitle(object sender, EventArgs e)
{
    textBoxTitle.Focus();
}