Question

我正在尝试使用<MultiBinding>将两个参数传递给我的ViewModel命令，但是在让XAML解析器接受我的尝试时遇到了问题。

考虑我的UserControl中包含的以下ListView，它绑定到Ticket个对象的集合。

<ListView x:Name="lvTicketSummaries" 
                  ItemsSource="{Binding TicketSummaries}"  
                  ItemContainerStyle="{DynamicResource ResourceKey=ListViewItem}"
                  IsSynchronizedWithCurrentItem="True">

各自的风格ListViewItem

<Style x:Key="ListViewItem" TargetType="{x:Type ListViewItem}">
    <Setter Property="ContextMenu" Value="{DynamicResource ResourceKey=cmListViewItem}"/>
    <!-- A load of irrelevant stuff ->
</Style>

我的查询源所在的引用ContextMenu项;

<!-- ContextMenu DataContext bound to UserControls view model so it can access 'Agents' ObservableCollection -->    
<ContextMenu x:Key="cmListViewItem" DataContext="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}}, Path=DataContext}">
    <MenuItem Header="Send as Notification" ItemsSource="{Binding Path=Agents}">
        <MenuItem.ItemContainerStyle>
            <Style TargetType="{x:Type MenuItem}">
                <!-- Display the name of the agent (this works) -->
                <Setter Property="Header" Value="{Binding Path=Name}"/>
                <!-- Set the command to that of one on usercontrols viewmodel (this works) -->
                <Setter Property="Command" Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type ContextMenu}}, Path=DataContext.SendTicketNotification}" />
                <Setter Property="CommandParameter">
                    <Setter.Value>
                        <MultiBinding Converter="{StaticResource ResourceKey=TicketNotificationParameterConverter}">
                            <MultiBinding.Bindings>
                                <!-- This SHOULD be the Agent object I clicked on to trigger the Command. This does NOT work, results in either exception or 'UnsetValue' -->
                                <Binding Source="{Binding}" />
                                <!-- Also pass in the Ticket item that was clicked on to open the context menu, this works fine -->
                                <Binding RelativeSource="{RelativeSource AncestorType={x:Type ListView}}" Path="SelectedItem" />
                            </MultiBinding.Bindings>
                        </MultiBinding>
                    </Setter.Value>
                </Setter>
            </Style>
        </MenuItem.ItemContainerStyle>
    </MenuItem>
</ContextMenu>

所以这就是我试图做的事情;

上下文菜单中有一个项目“作为通知发送票证”，选中后会列出可以接收所述通知的所有可用Agents。这有效。

当我点击其中一个代理选项时，我希望上下文菜单项同时发送从ticket点击的listview项目以显示上下文菜单（这我和从上下文菜单中选择的Agent项目。我用MultiBinding

完成了一半

<MultiBinding Converter="{StaticResource ResourceKey=TicketNotificationParameterConverter}">
                        <MultiBinding.Bindings>
                            <!-- This works, it sends the Ticket object to the Converter -->
                            <Binding RelativeSource="{RelativeSource AncestorType={x:Type ListView}}" Path="SelectedItem" />
                            <!-- This caused an exception saying that I can only set 'Path' property on DependencyProperty types -->
                            <Binding Path="{Binding}" />
                        </MultiBinding.Bindings>
                    </MultiBinding>

现在虽然上下文菜单的实际设置似乎有些让我感到困惑。其中一个MultiBinding参数应该是绑定到被点击的ContextMenu.MenuItem的实际项目的实际规范似乎是一个非常简单的命令。上下文菜单正确列出了所有代理，因此我认为只需要将当前对象作为命令参数发送，简单。我也试过了;

<Binding RelativeSource={RelativeSource AncestorType={x:Type MenuItem}} Path="SelectedItem" />

以及

<Binding RelativeSource={RelativeSource AncestorType={x:Type ContextMenu}} Path="SelectedItem" />

但是所有发送到参数转换器的都是UnsetValue

感谢您的时间和任何建议。

Answer 1

这条线很奇怪：

<Binding Path="{Binding}" />

当前的DataContext是否足以作为在当前DataContext中找到某些东西的路径，实际上不是字符串？有一个完美的感觉。

你的意思是这样做而不是绑定到DataContext吗？

<Binding />

包含在MultiBinding命令参数中绑定的对象

1 个答案: