带有MVVM Light的UserControl中的DependencyProperty

Question

如何使用MainViewModel属性绑定UserControl DepenpencyProperty。

MainViewModel.cs

public class MainViewModel : ViewModelBase
{
  public MainModel Model{get;set;}
  public MainViewModel()
  {
     Model = new MainModel();
  }
}

MainModel.cs

public class MainModel:ObservableObject
{
  private string text;
  public string Text
  {
    get{return text;}
    set{text=value;RaisePropertyChanged(()=>Text)}
}

MainView.xaml

<Window
    DataContext="{Binding Main, Source={StaticResource MainLocator}}">
<someusercontrol:controlEx DP={Binding Model.Text} />
</Window>

ControlEx.xaml

<UserControl  DataContext="{Binding Source={StaticResource Locator},Path=NewMain}" x:Class="someusercontrol.controlEx ">
</UserControl>

ControlEx.xaml.cs

 public partial class ControlEx:UserControl
 {
  public string DP
    {
        get
        {
            return (string)GetValue(DPProperty);
        }
        set
        {
            SetValue(DPProperty, value);
        }
    }
    public static readonly DependencyProperty DPProperty =
        DependencyProperty.Register(
        "DP",
        typeof(string),
        typeof(ControlEx),
        new FrameworkPropertyMetadata(new PropertyChangedCallback(OnDPPropertyChanged)));
    private static void OnDPPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        ControlEx source = d as ControlEx ;
        (source.DataContext as MainViewModel).Model.UserText= (string)e.NewValue;
       //// some actions
    }
}

此示例对我不起作用，ControlEx中的方法SetValue不会引发。如果我将DP = {Binding Model.Text}更改为DP = {＆＃34; 123＆＃34;}，一切正常。

解决

将绑定更改为

<Window
    DataContext="{Binding Main, Source={StaticResource MainLocator}}">
 <someusercontrol:controlEx DP={Binding Main.Model.Text, Source={StaticResource MainLocator}} />
</Window> 

它有效。