Question

我正在尝试创建一个菜单，当您在GridView中点击并按住某个项目时会出现该菜单。该菜单有一个从GridView源中删除项目的选项。当我点击“删除”选项时，如何引用最初点击的项目？这是Xaml：

<GridView Name="SharedBooksGrid" ScrollViewer.VerticalScrollBarVisibility="Hidden" ItemClick="BookClicked" IsItemClickEnabled="True" Grid.Row="3" Holding="SharedHold"  RightTapped="RightTapHold">
        <GridView.ItemTemplate>
            <DataTemplate>
                <Grid Height="250" Width="400">
                    <Image Source="{Binding BookImage}" Stretch="UniformToFill"/>
                    <Rectangle Opacity="0.35" Fill="Black" Height="60" VerticalAlignment="Top" />
                    <TextBlock Text="{Binding BookName}" FontSize="29" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="10" Foreground="White" />
                </Grid>
            </DataTemplate>
        </GridView.ItemTemplate>
        <FlyoutBase.AttachedFlyout>
            <MenuFlyout x:Name="SharedMenu">
                <MenuFlyoutItem Text="Make Default" />
                <MenuFlyoutSeparator />
                <MenuFlyoutItem Text="Delete" Click="DeleteShared_Tapped" />
            </MenuFlyout>
        </FlyoutBase.AttachedFlyout>
    </GridView>

背后的代码：

private Book deleteAccessBook;
private void RightTapHold(object sender, RightTappedRoutedEventArgs e)
{ 
    Point point = e.GetPosition(sender as UIElement);
    SharedMenu.ShowAt(sender as UIElement, point);
}

private async void DeleteShared_Tapped(object sender, RoutedEventArgs e)
{
    deleteAccessBook = e.OriginalSource as Book;
    bookAccessCollection = await BookAccessTable.ToCollectionAsync();
    foreach (var item in bookAccessCollection)
    {
        if (item.UserId == App.MobileService.CurrentUser.UserId)
        {
            if (item.BookId == deleteAccessBook.id)
            {
                await BookAccessTable.DeleteAsync(item);
            }
        }
    }
}

我的想法是e.OriginalSource将包含被点击的项目，但是当尝试从deleteAccessBook中查找id时会抛出异常。思考？谢谢！

Answer 1

我认为你应该能够通过获取holded元素的 DataContext 来获取 Book ：

<GridView Name="SharedBooksGrid" ScrollViewer.VerticalScrollBarVisibility="Hidden" ItemClick="BookClicked" IsItemClickEnabled="True" Grid.Row="3" Holding="SharedHold">
    <GridView.ItemTemplate>
        <DataTemplate>
            <Grid Height="250" Width="400" RightTapped="RightTapHold">
                <Image Source="{Binding BookImage}" Stretch="UniformToFill"/>
                <Rectangle Opacity="0.35" Fill="Black" Height="60" VerticalAlignment="Top" />
                <TextBlock Text="{Binding BookName}" FontSize="29" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="10" Foreground="White" />
            </Grid>
        </DataTemplate>
    </GridView.ItemTemplate>
    <FlyoutBase.AttachedFlyout>
        <MenuFlyout x:Name="SharedMenu">
            <MenuFlyoutItem Text="Make Default" />
            <MenuFlyoutSeparator />
            <MenuFlyoutItem Text="Delete" Click="DeleteShared_Tapped" />
        </MenuFlyout>
    </FlyoutBase.AttachedFlyout>
</GridView>

private Book deleteAccessBook;
private void RightTapHold(object sender, RightTappedRoutedEventArgs e)
{ 
    var holdedElement = e.OriginalSource as FrameworkElement;
    if (holdedElement == null) return;
    deleteAccessBook = holdedElement.DataContext as Book;
    SharedMenu.ShowAt(holdedElement);
}

private async void DeleteShared_Tapped(object sender, RoutedEventArgs e)
{
    if (deleteAccessBook == null) return;
    bookAccessCollection = await BookAccessTable.ToCollectionAsync();
    foreach (var item in bookAccessCollection)
    {
        if (item.UserId == App.MobileService.CurrentUser.UserId)
        {
            if (item.BookId == deleteAccessBook.id)
            {
                await BookAccessTable.DeleteAsync(item);
            }
        }
    }
}

点按并按住菜单以删除项

1 个答案: