组合框“的SelectedItem绑定到的DependencyProperty是不是清爽 [英] Combobox' SelectedItem bound to a DependencyProperty is not refreshing

问题描述

我有一个组合框，它的SelectedItem绑定到依赖项属性。

I have a combobox, whose SelectedItem is bound to a dependency property.

public IEnumerable<KeyValuePair<int,string>> AllItems
{
    get { return _AllItems; }
    set
    {
        _AllItems = value;
        this.NotifyChange(() => AllItems);
    }
}

public KeyValuePair<int, string> SelectedStuff
{
    get { return (KeyValuePair<int, string>)GetValue(SelectedStuffProperty); }
    set
    {
        SetValue(SelectedStuffProperty, value);
        LoadThings();
    }
}

public static readonly DependencyProperty SelectedStuffProperty =
    DependencyProperty.Register("SelectedStuff", typeof(KeyValuePair<int, string>), typeof(MyUserControl), new UIPropertyMetadata(default(KeyValuePair<int, string>)));

和XAML中：

<ComboBox DisplayMemberPath="Value"
          ItemsSource="{Binding AllItems}"
          SelectedItem="{Binding SelectedStuff, Mode=TwoWay}" />

中的数据正确绑定并显示，但是当我在组合框中选择其他值，设置不叫，也不是我的 LoadThings （）方法调用。

The data is correctly bound and displayed, but when I select another value in the combobox, the set is not called, neither is my LoadThings() method called.

有一个明显的原因是什么？

Is there an obvious reason ?

在此先感谢

我用snoop来查看组合框里面，当我改变的值，组合框'的SelectedItem也发生了变化。结果
我也查了code和属性被更改。但我的方法不叫（因为我不经过设置，所以这个问题依然存在...

I used snoop to view inside the combobox, and when I change the value, the combobox' SelectedItem is also changed.
I also checked in the code, and the property is changed. But my method is not called (as I don't go through the set, so the problem is still there...

推荐答案

好吧，我发现如何做到这一点。

Ok I found how to do that.

我宣布使用过载woth这样的回调我的DependencyProperty：

I declare my DependencyProperty using the overload woth the callback like this:

public static readonly DependencyProperty SelectedStuffProperty =
    DependencyProperty.Register("SelectedStuff", typeof(KeyValuePair<int, string>), typeof(MyUserControl), new UIPropertyMetadata(default(KeyValuePair<int, string>), new PropertyChangedCallback(SelectedStuffChanged));

和回调，我这样做：

private static void SelectedStuffChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    MyUserControl c = d as MyUserControl;
    c.LoadThings();
}

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