如何从LongListSelector获取单击的项目？ （WP8）

Question

我有一个LongListSelector与某种Items的ObservableCollection绑定。物品有许多不同的属性。

 <LongListSelector Name="DraftControl"  MouseLeftButtonDown="GoToEditDraft"> 
     <LongListSelector.ItemTemplate>
         <DataTemplate>
             ...
         </DataTemplate>
     <LongListSelector.ItemTemplate>
  </LongListSelector>

它有一个事件处理程序。但它获取整个LongListSelector的发送者，而不是特定的项目。如何为所有项添加事件处理程序？

这是一个处理程序的代码：

 private void GoToEditDraft(object sender, MouseButtonEventArgs mouseButtonEventArgs)
    {
        var clickerdItem = (LongListSelector)sender;
        MessageBox.Show(clickedItem.SelectedItem.ToString());
    }

因此，尝试以这种方式获取SelectedItem会抛出NullReferenceException。

数据模板：

 <DataTemplate>
 <Grid Margin="10" toolkit:TiltEffect.IsTiltEnabled="True">
     <Grid.Background>
         <SolidColorBrush Color="LightGray" Opacity="0.8"/>
     </Grid.Background>
     <Grid.ColumnDefinitions>
         <ColumnDefinition Width="120"/>
         <ColumnDefinition Width="*"/>
     </Grid.ColumnDefinitions>
     <Grid.RowDefinitions>
         <RowDefinition Height="Auto"/>
         <RowDefinition MaxHeight="100"/>
         <RowDefinition MaxHeight="30"/>
     </Grid.RowDefinitions>
     <TextBlock TextWrapping="Wrap" FontSize="28" Foreground="{StaticResource CustomApplicationTextBrush}" Text="{Binding Title, Converter={StaticResource SanitizeString}}" Margin="10,10,10,0" Grid.Column="0" Grid.Row="0" Grid.ColumnSpan="2"/>
     <Image Source="/Images/no-image.png" Stretch="UniformToFill" MaxHeight="100" Margin="10,10,0,10" Grid.RowSpan="1" Grid.Column="0" Grid.Row="1" VerticalAlignment="Top"/>
     <TextBlock TextWrapping="Wrap" FontSize="18" Foreground="{StaticResource CustomApplicationTextBrush}" TextTrimming="WordEllipsis" Text="{Binding Address, Converter={StaticResource SanitizeString}}" Margin="10,0,10,10" Grid.Column="1" Grid.Row="1" VerticalAlignment="Top"/>
 </Grid>
 </DataTemplate>

结合：

        ObservableCollection<Item> draftItems = new ObservableCollection<Item>();
        var draftStorage = IsolatedStorageFile.GetUserStoreForApplication();
        IReadOnlyList<StorageFile> allDrafts = await draftFolder.GetFilesAsync();
        foreach (StorageFile file in allDrafts)
        {                
            using (var stream = new IsolatedStorageFileStream("Drafts\\" + file.Name, FileMode.Open, draftStorage))
            {
                var fileReader = new StreamReader(stream);
                string jsonContents = fileReader.ReadLine();
                Item readedItem = JsonConvert.DeserializeObject<Item>(jsonContents);

                draftItems.Add(readedItem);
                fileReader.Close();
            }
        }
        DraftControl.ItemsSource = draftItems;

Answer 1

试试这个。

private void DraftControl_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    var myItem = ((Item)(sender as LongListSelector).SelectedItem);
}

Answer 2

订阅LongListSelectors SelectionChangedEvent而不是

<LongListSelector Name="DraftControl" SelectionChanged="lls_SelectionChanged"> 
     <LongListSelector.ItemTemplate>
         <DataTemplate>
             ...
         </DataTemplate>
     <LongListSelector.ItemTemplate>
  </LongListSelector>

并获取后面代码中的项目

private void lls_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
  var myItem = ((LongListSelector) sender).SelectedItem as Type;
}