使用 WPF 时的数据绑定问题

我一直在努力学习Visual C#。最近，我一直在关注WPF。这是我一直在制作的教程的链接：

http://msdn.microsoft.com/en-us/library/vstudio/ms752299(v=vs.110).aspx http://msdn.microsoft.com/en-us/library/vstudio/ms752299%28v=vs.110%29.aspx

如果您选择某个人的姓名并单击“查看”按钮，应用程序应该允许您查看该人的开支。不幸的是，费用没有显示。我不断收到此错误消息：

System.Windows.Data Error: 50 : XmlDataProvider has inline XML that does not explicitly set its XmlNamespace (xmlns="").

我认为 xmlns 需要留空，以便应用程序可以在 XAML 中向下导航。这是我制作的网格资源的代码：

<Grid.Resources>
            <!-- Expense Report Data -->
            <XmlDataProvider x:Key="ExpenseDataSource" XPath="Expenses">
                <x:XData>
                    <Expenses xmlns="">
                        <Person Name="Mike" Department="Legal">
                            <Expense ExpenseType="Lunch" ExpenseAmount="50" />
                            <Expense ExpenseType="Transportation" ExpenseAmount="50" />
                        </Person>
                        <Person Name="Lisa" Department="Marketing">
                            <Expense ExpenseType="Document Printing" ExpenseAmount="50" />
                            <Expense ExpenseType="Gift" ExpenseAmount="125" />
                        </Person>
                        <Person Name="John" Department="Engineering">
                            <Expense ExpenseType="Magazine Subscription" ExpenseAmount="50" />
                            <Expense ExpenseType="New Machine" ExpenseAmount="600" />
                            <Expense ExpenseType="Software" ExpenseAmount="500" />
                        </Person>
                        <Person Name="Mary" Department="Finance">
                            <Expense ExpenseType="Dinner" ExpenseAmount="100" />
                        </Person>
                    </Expenses>
                </x:XData>
            </XmlDataProvider>

            <!-- Name item template -->
            <DataTemplate x:Key="nameItemTemplate">
                <Label Content="{Binding XPath=@Name}"/>
            </DataTemplate>

</Grid.Resources>

谁能给我任何关于出了什么问题的提示吗？

Thanks

事实证明问题不在于网格资源！我忘记在 DataGrid 中设置 ItemsSource。在我的 ExpenseReportPage.xaml 文件中，我输入了以下内容：

<Grid Grid.Column="0" Grid.ColumnSpan="2" Grid.Row="2" VerticalAlignment="Top"
                  HorizontalAlignment="Left">
                <!-- Expense type and Amount table -->
                <DataGrid ItemsSource="{Binding XPath=Expense}" ColumnHeaderStyle="{StaticResource columnHeaderStyle}" 
                          AutoGenerateColumns="False" RowHeaderWidth="0">
                    <DataGrid.Columns>
                        <DataGridTextColumn Header="Expense Type" Binding="{Binding XPath=@ExpenseType}" />
                        <DataGridTextColumn Header="Amount" Binding="{Binding XPath=@ExpenseAmount}"/>
                    </DataGrid.Columns>
                </DataGrid>
</Grid>

设置ItemsSource后，数据正​​常显示。