使用LinQ從組合框選擇中選擇C＃篩選器列表框

Question

我有一個名為lstTickets的列表框和一個名為cboFilter的組合框。 我正在嘗試根據票證。組合框中的票證過濾列表框中的項目。 因此，例如，如果我從combox中選擇，則是列表框中的唯一團隊。 任何幫助表示贊賞。

 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>

編輯：在mainpage.cs中填充組合框

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

Answer 1

看起來ToString（）對所選項目無效。

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

確保在搜索字詞上放置一個斷點，以查看其正確值是否正確

但我想我知道您的問題，所選項目將返回整個對象，因此請執行以下操作

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

Answer 2

嘗試先檢查您在cboFilter.SelectedItem中是否有實際值，然后再使用小寫字母比較這些值。 我更喜歡使用System.Linq，所以我更改了您的查詢以使用該代碼：

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;

}