用户控件的子抚养对象绑定不工作 [英] Bindings on child dependency object of usercontrol not working

问题描述

我想获得一个绑定的用户控件的子对象上工作。 XAML中看起来是这样的：

I'm trying to get a binding to work on a child object of a user control. The Xaml looks like this:

<MyGrid>
    <MyColumn ExtendedColumnData="{Binding ColumnToolTipDescriptions}"/>
</MyGrid>

下面是这些类是如何定义的：

Here is how the classes are defined:

[ContentProperty("Columns")]
public class MyGrid : UserControl
{
    private MyColumnCollection _columns;

    [DesignerSerializationVisibility(DesignerSerializationVisibility.Content), Category("Data")]
    public MyColumnCollection Columns
    {
        get
        {
            if (_columns == null)
                _columns = new MyColumnCollection();

            return _columns;
        }
    }
}

public class MyColumnCollection : ObservableCollection<MyGridColumn>
{
}

public class MyGridColumn : DependencyObject
{
    public object ExtendedColumnData
    {
        get { return (object)GetValue(ExtendedColumnDataProperty); }
        set { SetValue(ExtendedColumnDataProperty, value); }
    }

    public static readonly DependencyProperty ExtendedColumnDataProperty =
        DependencyProperty.Register("ExtendedColumnData", typeof(object), typeof(MyGridColumn), new UIPropertyMetadata(null));
}

从我所知道的，结合甚至没有试图获取的数据，因为我已经试图把一个转换器对绑定，并在转换方法断点从来没有被击中。

From what I can tell, the binding is not even attempting to get the data as I've tried putting a converter against the binding, and the breakpoint on the Convert method never gets hit.

我使用的MVVM模式，使窗口的的DataContext 属性设置为视图模型。

I'm using the MVVM pattern so the window's DataContext property is set to a view model.

我读过关于这里的一些其他问题，并尝试了各种排列的结合，例如：

I've read some other questions on here and tried various permutations of the binding such as:

<MyColumn ExtendedColumnData="{Binding DataContext.ColumnToolTipDescriptions, ElementName=MyViewName}" />
<MyColumn ExtendedColumnData="{Binding DataContext.ColumnToolTipDescriptions, RelativeSource={RelativeSource AncestorType={x:Type local:MyView}}" />

但仍然没有运气，结合不火！恼人的是，这似乎工作正常（如果我的属性添加到网格）：

But still no luck, the binding doesn't fire! The annoying thing is, this seems to work fine (if I add the property to the grid):

<MyGrid ExtendedColumnData="{Binding ColumnToolTipDescriptions}">
    <MyColumn />
</MyGrid>

我不与WPF经历，所以我敢肯定，我失去了一些东西？

I'm not that experienced with WPF so I'm sure I'm missing something?

推荐答案

的问题是， MyColumnCollection 不继承数据上下文（控制的常用属性都没有的一部分继承上下文）。如果你没有一个数据上下文绑定将无法工作。

The problem is that MyColumnCollection is not inheriting data context (usual properties of a control are not part of inheritance context). If you don't have a data context bindings will not work.

要解决这个问题，尝试继承 MyColumnCollection 从的ObservableCollection ，而是来自的FreezableCollection （可冻结属性继承上下文的一部分）。

To fix that, try inheriting MyColumnCollection not from ObservableCollection, but from FreezableCollection (freezable properties are part of inheritance context).

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