在 c# Xamarin 上显示来自 db 的 ListView 数据时，有没有办法从屏幕而不是字符串中删除 System.Collection.Generic 消息

Question

I want when the user clicks on my first listView to show a second listview with different data from database, but I see this Message: "System.Collections.Generic.List'1[System..."

When I use debugger everything is fine.. I see the data from the date base..

My second listview look like this:

           <StackLayout>
              <ListView x:Name="MeteoView"
                        ItemsSource="{Binding Forecast}"
                        HeightRequest="100"
                        IsVisible="false">
                <ListView.ItemTemplate>
                  <DataTemplate>
                    <TextCell 
                        Text="{Binding DisplayRun}" />
                  </DataTemplate>
                </ListView.ItemTemplate>
            </ListView>
        </StackLayout>

My c# code to connect with db, execute the procedure and display the data look like this:

 public class ForecastData
    {
        public string DisplayRun { get; set; }
    }

    ObservableCollection<ForecastData> MeteoData = new ObservableCollection<ForecastData>();
    public ObservableCollection<ForecastData> Forecast { get { return MeteoData; } }

    void listView_ItemSelected(System.Object sender, Xamarin.Forms.SelectedItemChangedEventArgs e)
    {    

        string str = ((Contacts)listView.SelectedItem).Place;

        string substr = str.Substring(str.Length - 5);

        searchBar.Placeholder = str;

        server = "ip-to-db";
        database = "db-name";
        uid = "user";
        password = "pass";
        string connectionString;
        connectionString = "SERVER=" + server + ";" + "DATABASE=" +
        database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";";
        connection = new MySqlConnection(connectionString);


        List<string> Run = new List<string>();
        
        
        try
        {
            connection.Open();
            var cmd = new MySqlCommand();
            cmd.Connection = connection;
            MySqlCommand command = new MySqlCommand($"CALL `get_all_data`({substr})", connection);

            MeteoView.IsVisible = true;
            MeteoView.ItemsSource = MeteoData;

            using (MySqlDataReader reader = command.ExecuteReader())
            {
                while (reader.Read())
                {

                    Run.Add(reader[0].ToString()); 

                    MeteoData.Add(new ForecastData { DisplayRun = $"{Run}" });
                }
            }
            connection.Close();
        }

        catch (Exception ex)
        {
            LabelSQL.Text = (ex.ToString());
        }       
    }

So on my display emulator I see this one in the listView:

listView

Debugger

Answer 1

this is essentially the same problem you asked about earlier today. By default ToString will return the name of the class. You are setting DisplayRun to the contents of a List<string>

List<string> Run = new List<string>();

Run.Add(reader[0].ToString()); 
MeteoData.Add(new ForecastData { DisplayRun = $"{Run}" });

which is basically the same as

DisplayRun = Run.ToString();