C# LongListSelector+；所选项目-如何读取每个单独的属性？（WP8，Azure数据库）

我有一个LongListSelector，用于存储来自Azure SQL数据库的数据

这是我的C代码：

 private async void RefreshTodoItemsToday()
    {
        try
        {
            coll = await todoTable
                .Where(todoItem => todoItem.TpEvt == "today")
                .ToCollectionAsync();
        }
        catch (MobileServiceInvalidOperationException e)
        {
            MessageBox.Show(e.Message, "Error loading items", MessageBoxButton.OK);
        }

        ListItemstoday.ItemsSource = coll;
    }

<phone:LongListSelector Name="ListItemsToday">
                <phone:LongListSelector.ItemTemplate>
                    <DataTemplate>
                        <StackPanel>

                                <TextBlock Name="TxtEvt" Text="{Binding Text}" TextWrapping="Wrap" Foreground="Gray" TextAlignment="Center" FontSize="30" Padding="30">
                                </TextBlock>

                        <Line X1="0" Y1="10" X2="240" Y2="10" Stroke="SkyBlue" HorizontalAlignment="Center" VerticalAlignment="Center" Height="21"/>
                        </StackPanel>
                    </DataTemplate>
                </phone:LongListSelector.ItemTemplate>
                </phone:LongListSelector>

var tmp1 = (TodoItem)ListItemsToday.SelectedItem; 
var tmp2 = tmp1.Id;
MessageBox.Show(tmp2.ToString());

这是我的XAML:

 private async void RefreshTodoItemsToday()
    {
        try
        {
            coll = await todoTable
                .Where(todoItem => todoItem.TpEvt == "today")
                .ToCollectionAsync();
        }
        catch (MobileServiceInvalidOperationException e)
        {
            MessageBox.Show(e.Message, "Error loading items", MessageBoxButton.OK);
        }

        ListItemstoday.ItemsSource = coll;
    }

<phone:LongListSelector Name="ListItemsToday">
                <phone:LongListSelector.ItemTemplate>
                    <DataTemplate>
                        <StackPanel>

                                <TextBlock Name="TxtEvt" Text="{Binding Text}" TextWrapping="Wrap" Foreground="Gray" TextAlignment="Center" FontSize="30" Padding="30">
                                </TextBlock>

                        <Line X1="0" Y1="10" X2="240" Y2="10" Stroke="SkyBlue" HorizontalAlignment="Center" VerticalAlignment="Center" Height="21"/>
                        </StackPanel>
                    </DataTemplate>
                </phone:LongListSelector.ItemTemplate>
                </phone:LongListSelector>

var tmp1 = (TodoItem)ListItemsToday.SelectedItem; 
var tmp2 = tmp1.Id;
MessageBox.Show(tmp2.ToString());

当我尝试强制转换此代码时，出现以下错误：

*System.NullReferenceException:对象引用未设置为对象的实例。 在Project.MainPage.ContextMenuRemove\单击（对象发送方，事件参数e）*

有人能帮我吗？

---

感谢您的朋友。

对更改的选择做出反应：

<phone:LongListSelector Name="ListItemsToday" SelectionChanged="ListItemsToday_SelectionChanged">
    <phone:LongListSelector.ItemTemplate>
        <DataTemplate>
            <StackPanel>

                <TextBlock Name="TxtEvt" Text="{Binding Text}" TextWrapping="Wrap" Foreground="Gray" TextAlignment="Center" FontSize="30" Padding="30">
                </TextBlock>

                <Line X1="0" Y1="10" X2="240" Y2="10" Stroke="SkyBlue" HorizontalAlignment="Center" VerticalAlignment="Center" Height="21"/>
            </StackPanel>
        </DataTemplate>
    </phone:LongListSelector.ItemTemplate>
</phone:LongListSelector>

或对数据模板中的点击事件作出反应

<phone:LongListSelector Name="ListItemsToday" >
    <phone:LongListSelector.ItemTemplate>
        <DataTemplate>
            <StackPanel Tap="ListItemsToday_Tap">

                <TextBlock Name="TxtEvt" Text="{Binding Text}" TextWrapping="Wrap" Foreground="Gray" TextAlignment="Center" FontSize="30" Padding="30">
                </TextBlock>

                <Line X1="0" Y1="10" X2="240" Y2="10" Stroke="SkyBlue" HorizontalAlignment="Center" VerticalAlignment="Center" Height="21"/>
            </StackPanel>
        </DataTemplate>
    </phone:LongListSelector.ItemTemplate>
</phone:LongListSelector>

---

Hi-igrali，是否可以获取LLS的选定ui项，我的意思是，如果我将网格作为数据模板，是否可以在selection changed事件中将网格作为选定项获取。