使用LinQ从组合框选择中选择C＃筛选器列表框

Question

我有一个名为lstTickets的列表框和一个名为cboFilter的组合框。 我正在尝试根据票证。组合框中的票证过滤列表框中的项目。 因此，例如，如果我从combox中选择，则是列表框中的唯一团队。 任何帮助表示赞赏。

 List<Ticket> = new List<Ticket>()
    {
        new Ticket { Name = "Arsenal", Badge = "images/arsenal.jpg", Price = 900, Stadium = "emirates.jpg", District = "London" },
        new Ticket { Name = "Tottenham Hotspur", Badge = "images/tottenham.jpg", Price = 850, Stadium = "tottenham.jpg", District = "" },
        new Ticket { Name = "Manchester United", Badge = "images/.png", Price = 1000, Stadium = "oldtrafford.jpg", District = "" },
    };

 private void cboFilter_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
       var query = from Ticket in tickets where cboFilter.SelectedItem.ToString() == Ticket.District select Ticket;

        lstTickets.ItemsSource = null;
        lstTickets.Items.Clear();

        List<Ticket> tmp = new List<Ticket>();

        foreach (var tickets in query)
        {
            tmp.Add(tickets);

        }
        lstTickets.ItemsSource = tmp;

    }



                        <Image Width="200" Height="150" HorizontalAlignment="Left" Source="{x:Bind Badge }" />
                        <TextBlock FontSize="22" HorizontalAlignment="Left" Text="{x:Bind Name}" Style="{StaticResource HeaderTextBlockStyle}"/>
                        <TextBlock FontSize="16" HorizontalAlignment="Left"> € <Run Text="{Binding Price}" /></TextBlock>
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

编辑：在mainpage.cs中填充组合框

private void myGrid_Loaded(object sender, RoutedEventArgs e)
    {
    }

Answer 1

看起来ToString（）对所选项目无效。

var searchTerm=  cboFilter.SelectedItem.ToString();
var query = from Ticket in tickets where Ticket.District == term  select Ticket;

确保在搜索字词上放置一个断点，以查看其正确值是否正确

但我想我知道您的问题，所选项目将返回整个对象，因此请执行以下操作

var selectedTicked=  cboFilter.SelectedItem as Ticket;
var searchTerm= selectedTicket.District 
    var query = from Ticket in tickets where Ticket.District == term  select Ticket;

Answer 2

尝试先检查您在cboFilter.SelectedItem中是否有实际值，然后再使用小写字母比较这些值。 我更喜欢使用System.Linq，所以我更改了您的查询以使用该代码：

private void cboFilter_SelectionChanged(object sender, SelectionChangedEventArgs e)
{

   var comboBoxItem = cboFilter.SelectedItem as ComboBoxItem;

   if(comboBoxItem == null) return; // or log an error here or something if it should not be empty.

   var query = tickets.Where(t => t.District.ToLower() == comboBoxItem.Content.ToString().ToLower());

    lstTickets.ItemsSource = null;
    lstTickets.Items.Clear();

    List<Ticket> tmp = new List<Ticket>();

    foreach (var tickets in query)
    {
        tmp.Add(tickets);

    }
    lstTickets.ItemsSource = tmp;

}