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将Silverlight自定义控件依赖项属性绑定到模型属性

dependency-properties silverlight-3.0 mvvm silverlight

Nick Gotch · 技术社区 · 15 年前

我在Silverlight中有一个数据导航用户控件,它打开一个子窗口,用户可以在其中输入搜索条件,当他们按“应用”时,它将更新ViewModel(MVVM模式)中的绑定属性。

链接为:搜索对话框<-->数据导航器<-->我的视图<-->我的视图模型

SearchDialog中的Dependency属性似乎可以工作,当我设置其值时,它会显示在DataNavigator中;但是当Dependency属性更改时,似乎没有从DataNavigator向MyView/MyViewModel发送通知。

SearchDialog从ChildWindow派生:

public string Search
{
 get { return (string)GetValue(SearchProperty); }
 set { SetValue(SearchProperty, value); }
}

public static readonly DependencyProperty SearchProperty =
 DependencyProperty.Register("Search", typeof(string), typeof(SearchDialog),
 new PropertyMetadata(null));

数据导航器从用户控件派生:

public Binding Search { get; set; }

private void DataNavigator_Loaded(object sender, Windows.RoutedEventArgs e)
{
 if (Search != null)
  this._searchDialog.SetBinding(SearchDialog.SearchProperty, Search);
}

myview从silverlightfx.userinterface.navigation.page派生:

<DataNavigator MovePreviousAction="$model.MovePrevious()"
               CurrentIndex="{Binding CurrentIndex, Mode=TwoWay}"
               MoveNextAction="$model.MoveNext()"
               SaveAction="$model.SaveChanges()"
               IsLoading="{Binding IsLoading, Converter={StaticResource VisibilityConverter}}"
               Search="{Binding SearchString, Mode=TwoWay}"/>

MyViewModel从ViewModel派生:

public string SearchString
    {
     get { return this._search; }

  set
  {
   if(value != this._search)
   {
    this._search = value;
    this.RaisePropertyChanged("SearchString");
   }
  }
 }

我花了好几个小时试图找出问题所在,但没有取得任何成功;有人看到这个问题吗?事先谢谢,

2 回复 | 直到 14 年前

Bryant 15 年前

不确定中间的绑定属性是否有效,因为您正试图将其绑定到string类型的属性。

既然你已经在用尼基的东西了,你可能想看看 how he uses Tasks to handle dialogs/child windows 同时保持MVVM范式的位置。

Community CDub 7 年前

Bryant's solution 看起来不错,但我还是有些问题。我最终使用了以下方法使其工作:

我在SearchDialog中添加了一个事件,当搜索模式dp更改时将触发该事件:

public string Search
{
    get { return (string)GetValue(SearchProperty); }
    set { SetValue(SearchProperty, value); }
}

public static readonly DependencyProperty SearchProperty =
    DependencyProperty.Register("Search", typeof(string), typeof(SearchDialog),
    new PropertyMetadata(null, new PropertyChangedCallback(OnSearchChanged)));

private static void OnSearchChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    // call to instance method
    ((SearchDialog)d).OnSearchChanged(e);
}

protected virtual void OnSearchChanged(DependencyPropertyChangedEventArgs e)
{
    if (SearchChanged != null)
        this.SearchChanged(this, e);
}

public event DependencyPropertyChangedEventHandler SearchChanged;

在此之后,我在数据导航器中添加了另一个DP:

public string Search
{
    get { return (string)GetValue(SearchProperty); }
    set { SetValue(SearchProperty, value); }
}

public static readonly Windows.DependencyProperty SearchProperty =
Windows.DependencyProperty.Register("Search", typeof(string), typeof(DataNavigator),
new Windows.PropertyMetadata(null));

然后将导航器的DP连接到SearchDialog的DP,以便将对搜索属性的更改传播到数据导航器,然后将数据导航器绑定到V&VM。

// Inside the Loaded Event:
this._searchDialog.SearchChanged +=
    new System.Windows.DependencyPropertyChangedEventHandler(Search_Changed);

// Handler:
private void Search_Changed(object sender, System.Windows.DependencyPropertyChangedEventArgs e)
{
    string search = this._searchDialog.GetValue(SearchDialog.SearchProperty) as string;
    this.Search = search != null ? search.ToString() : null;
}

其余的事情和上面一样,我得到了我想要的效果。