WPF，XAML中使用XPath与XmlDataProvider基于在ComboBox中选定的价值选择的节点 [英] WPF, using XPath in XAML with XmlDataProvider to select nodes based on selected value in ComboBox

问题描述

这个问题关系到我的先前的问题但更具体。说我有两个组合框，一是填充了产品名称，其他空。当选择一个产品，我想在第二组合框来填充与该产品相关的数据。我有XML这样的：

This question ties to my previous question but is more specific. Say I have two ComboBoxes, one populated with product names, the other empty. When a product is chosen, I want the second ComboBox to be filled with data related to that product. I have XML like the following:

<Products>
    <Product name="MyProduct1">
        <Components>
            <Component name="MyComponent1"/>
            <Component name="MyComponent2"/>
            ...more Component nodes...
        </Components>
    </Product>
    ...more Product nodes...
</Products>

我希望的是，我可以以某种方式将的XPath 的组件组合框，这样它会从产品，其节点的所有组件/组件节点 @name 属性等于在产品组合框中当前所选的值。这可能吗？我会怎么做呢？下面是我在我的XAML至今：

What I was hoping is that I could somehow set the XPath on the Component ComboBox such that it gets all the Components/Component nodes from the Product node whose @name attribute is equal to the currently selected value in the Product ComboBox. Is this possible? How would I do it? Here's what I have in my XAML so far:

<ComboBox Height="23" HorizontalAlignment="Left" Margin="138,116,0,0"
          Name="cbo_product" VerticalAlignment="Top" Width="120"
          ItemsSource="{Binding Source={StaticResource productsXml}}"
          DisplayMemberPath="@name"/>
<ComboBox Height="23" HorizontalAlignment="Left" Margin="138,151,0,0"
            Name="cbo_component" VerticalAlignment="Top" Width="201"
            DisplayMemberPath="@name">
    <ComboBox.ItemsSource>
        <!-- Currently gets all Component nodes--want it to get only those
             associated with the selected Product -->
        <Binding Source="{StaticResource productsXml}"
                 XPath="Components/Component"/>
    </ComboBox.ItemsSource>
</ComboBox>

该产品组合框充满了像MyProduct1产品名称，所以这部分很不错。这是依赖组件组合框我需要帮助。

The Product ComboBox is filled with product names like MyProduct1, so that part is fine. It's the dependent Component ComboBox I need help with.

推荐答案

周围的Googling在WPF XPath表达式的例子后，我发现<一个HREF =htt​​p://karlhulme.wordpress.com/2007/02/14/xpath-variabledynamic-parameters-in-wpf-binding/相对=nofollow>这篇文章给了我我的解决方案一个迂回的方式。他的例子比我更复杂，所以我没有去创建XML转换器类。我只是需要以下XAML我依赖的组件组合框：

After Googling around for examples of XPath expressions in WPF, I found this article that gave me my solution in a round-about way. His example was more complicated than mine, so I didn't have to go creating XML converter classes. I just needed the following XAML for my dependent Component ComboBox:

<ComboBox Height="23" HorizontalAlignment="Left" Margin="138,151,0,0"
          Name="cbo_component" VerticalAlignment="Top" Width="201"
          DataContext="{Binding ElementName=cbo_product, Path=SelectedItem}"
          ItemsSource="{Binding XPath=Components/Component}"
          DisplayMemberPath="@name"/>

在这里， cbo_product 是名称我的产品组合框的。

Here, cbo_product is the Name of my Product ComboBox.

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