上下文菜单绑定到父窗口的数据上下文 [英] Context Menu Binding to Parent Window's Datacontext

问题描述

我有一个 TreeListControl 绑定到我的 VM 中的集合.我还想在 treelistcontrol 中定义上下文菜单，使其标题文本绑定到我的 VM 中的另一个字符串.在这种情况下如何设置数据上下文?我试着

I have a TreeListControl that binds to a collection in my VM. I also want to define the context menu inside the treelistcontrol having its header text bind to another string in my VM. how can I set the data context in this case? I tried to

<Window.DataContext>
    <model:ViewModel></model:ViewModel>
</Window.DataContext>
<Grid>
<Button Grid.Row="1"  Command="{Binding CellCheckedCommand}"></Button>

    <TextBlock Text="{Binding HeaderText}" Grid.Row="2">
        <TextBlock.ContextMenu>
            <ContextMenu>
                <MenuItem DataContext="{Binding RelativeSource={RelativeSource AncestorType={x:Type Window}}, Path=DataContext}"  Header="{Binding HeaderText}"></MenuItem>
            </ContextMenu>
        </TextBlock.ContextMenu>
    </TextBlock>
</Grid>

但它不起作用.

这是视图模型

public DelegateCommand CellCheckedCommand { get; set; }

private String _HeaderText;

public String HeaderText 
{
    get
    {
        return _HeaderText;
    }
    set
    {
        _HeaderText = value;
        NotifyPropertyChanged("HeaderText");
    }
}

public void NotifyPropertyChanged(String name)
{ 
    if(PropertyChanged != null)
    {
        PropertyChanged(this, new PropertyChangedEventArgs(name));
    }
}

private void CellCheckedMethod()
{
    HeaderText = "Changed";
}

推荐答案

为您的窗口提供一个名称并明确绑定到它，例如

Provide a name for your window and explicitly bind to it such as

<window  x:Name="ReportsPage"/>

...

 <MenuItem DataContext="{Binding ElementName=ReportsPage}"/>

<小时>

更新

因为上下文菜单实际上在它自己的窗口中，所以绑定有点棘手.因此，最好的办法是将 RelativeSource 走上上下文的父级并从那里拉出标题文本:

Since the context menu is actually in its own window, binding is a bit trickier. Hence the best bet is to walk up the RelativeSource to the context's parent and pull the header text from there:

    <Window.DataContext>
        <local:MainVM HeaderText="Jabberwocky" />
    </Window.DataContext>

    ...

<TextBlock Text="{Binding HeaderText}">
    <TextBlock.ContextMenu>
        <ContextMenu>

<MenuItem Header="{Binding Path=Parent.DataContext.HeaderText, 
                    RelativeSource={RelativeSource Self}}" />

        </ContextMenu>
    </TextBlock.ContextMenu>

对于这个上下文产生这个

Which for this context produces this

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