数据绑定到XAML中的XmlDataProvider而不显示数据

Question

I am trying to make a very simple ListBox view that shows items from a short list as labels. However, the window pops up blank. XAML:

<Window x:Class="ReCheckList.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:ReCheckList"
    mc:Ignorable="d"
    Title="MainWindow" Height="298" Width="192">
<Window.Resources>
<!----- Data Source ---------->
    <XmlDataProvider x:Key="PackingListDataSource" XPath="cList">
        <x:XData>
            <Checklist xmlns="">
                <ListNode Title="Socks"/>
                <ListNode Title="Shoes"/>
                <ListNode Title="Toothbrush"/>
            </Checklist>
        </x:XData>
    </XmlDataProvider>
<!--- Data Template ----------->
    <DataTemplate x:Key="ListNodeTemplate">
        <Label Content="{Binding XPath=@Title}"></Label>
    </DataTemplate>
</Window.Resources>
<Grid>
<!------ ListBox ------->
    <ListBox ItemsSource="{Binding Source={StaticResource PackingListDataSource}, XPath=ListNode}"
             ItemTemplate="{StaticResource ListNodeTemplate}">
    </ListBox>
</Grid>

What is wrong with my data bindings?

---

EDIT: The most fundamental error was that the XPath of the XmlDataProvider did not match the root node of the xml data. Changing that to "Checklist" was the simplest fix, not requiring modifying my XPath search parameters.

Answer 1

ListNode seems just like the wrong XPath here, did you mean //ListNode or /Checklist/ListNode ? Also, you set an XPath on the provider that does not appear in the data, would remove that.

Answer 2

First, remove the XPath attribute from the XmlDataProvider

<XmlDataProvider x:Key="PackingListDataSource">
    <x:XData>
        <Checklist xmlns="">
            <ListNode Title="Socks"/>
            <ListNode Title="Shoes"/>
            <ListNode Title="Toothbrush"/>
        </Checklist>
    </x:XData>
</XmlDataProvider>

Then, fix the XPath in the ItemsSource binding so it returns all ListNodes in the XML. In practice you might want to narrow it down more, but this at least gets me items in the ListBox .

<ListBox 
    ItemsSource="{Binding Source={StaticResource PackingListDataSource}, XPath='//ListNode'}"
    ItemTemplate="{StaticResource ListNodeTemplate}"
    >
</ListBox>

// means "Search the whole XML tree for any element with this name". Leaving that out, you're only searching the element you're looking at for anything with that name. In this case, you're looking at the root. You could explicitly start the path at root by prefacing the path with a single slash: /CheckList/ListNode .

Alternatively (I'm learning as I go here), you could leave the binding XPath as you had it, and just change the XPath attribute of the XmlDataProvider to Checklist , so your binding will look in Checklist for ListNode elements. Your problem was really just that cList was wrong for that XPath attribute because you don't have anything called cList at the root of your XML.

<XmlDataProvider x:Key="PackingListDataSource" XPath="Checklist">
    <x:XData>
        <Checklist xmlns="" Title="Foo">
            <ListNode Title="Socks"/>
            <ListNode Title="Shoes"/>
            <ListNode Title="Toothbrush"/>
        </Checklist>
    </x:XData>
</XmlDataProvider>

...

<ListBox 
    ItemsSource="{Binding Source={StaticResource PackingListDataSource}, XPath='ListNode'}"
    ItemTemplate="{StaticResource ListNodeTemplate}"
    >
</ListBox>

Remember that XML is case sensitive, so Checklist is not CheckList . And when I say you need to remember that, I really mean that I forgot it.

Answer 3

<!-- change the XPath to "Checklist" -->
<XmlDataProvider x:Key="PackingListDataSource" XPath="cList">
    <x:XData>
        <Checklist xmlns="">
            <ListNode Title="Socks"/>
            <ListNode Title="Shoes"/>
            <ListNode Title="Toothbrush"/>
        </Checklist>
    </x:XData>
</XmlDataProvider>