C# WPF datagrid format timespan

Question

I'm trying to programmatically bind data from a list to a GridView in WPF. It works perfectly, but I want to format a TimeSpan column to my needs, but when I use any StringFormat, the column just stays empty.

I have following (simplified) code:

foreach (var song in _manager.GetLibrarySongs())
{
    LibraryView.Items.Add(song);
}

DataGridTextColumn durationColumn = new DataGridTextColumn
{
    Header = "Duration",
    Binding = new Binding("Duration") { StringFormat = "" }
};
LibraryView.Columns.Add(durationColumn);

Stringformat is empty here but whatever I put in there, it makes the column just empty. I tried "hh\:mm\:ss", "hh\:mm\\:ss", "{}{0:g}", ...

Does anyone know what I'm doing wrong? Thanks in advance!

Answer 1

Following code has been used in Visual Studio 2015 and have DataGrid with DateTime and TimeSpan columns with defined format.

For date following string is used "yyyy-MM-dd" while for time string "mm\:ss" is used (notice double back slash)

public partial class MainWindow : Window {
    public MainWindow() {
        InitializeComponent();

        dataGrid = new DataGrid();

        var stackPanel = new StackPanel { Orientation = Orientation.Vertical };
        stackPanel.Children.Add(dataGrid);

        Content = stackPanel;

        Rnd = new Random();
        Now = DateTime.Now;
        Counter = 1;

        foreach (var song in GetSongs())
            dataGrid.Items.Add(song);

        // var timeSpanConverter = new TimeSpanConverter();
        var titleColumn = new DataGridTextColumn { Header = "Title", Binding = new Binding("Title") };
        var authorColumn = new DataGridTextColumn { Header = "Author", Binding = new Binding("Author") };
        var albumColumn = new DataGridTextColumn { Header = "Album", Binding = new Binding("Album")};
        // var durationColumn = new DataGridTextColumn {Header = "Duration", Binding = new Binding("Duration") { Converter = timeSpanConverter }   };
        var durationColumn = new DataGridTextColumn { Header = "Duration", Binding = new Binding("Duration") { StringFormat = "mm\\:ss" } };
        var releaseColumn = new DataGridTextColumn { Header = "Release", Binding = new Binding("Release") { StringFormat = "yyyy-MM-dd" } };

        dataGrid.Columns.Add(titleColumn);
        dataGrid.Columns.Add(authorColumn);
        dataGrid.Columns.Add(albumColumn);
        dataGrid.Columns.Add(durationColumn);
        dataGrid.Columns.Add(releaseColumn);
    }

    private DataGrid dataGrid;

    private int? Counter;
    private DateTime? Now;
    private Random Rnd;

    private TimeSpan GetDuration() { return TimeSpan.FromSeconds(30 + Rnd.Next(500)); }
    private DateTime GetRelease() { Counter += 1; return Now.Value.AddMilliseconds(Counter.Value); }
    private string GetTitle() { return $"Title {Counter}"; }
    private string GetAlbum() { return $"Album {Counter}"; }
    private string GetAuthor() { return $"Author {Counter}"; }

    private IList<Song> GetSongs()
    {
        var list = new List<Song>();

        for(var i = 0; i < 1000; i++)
            list.Add(new Song() {
                Title = GetTitle(),
                Album = GetAlbum(),
                Author = GetAuthor(),
                Release = GetRelease(),
                Duration = GetDuration()
            });
        return list;
    }
}

public class Song {
    public string Title { get; set; }
    public string Author { get; set; }
    public string Album { get; set; }
    public DateTime Release { get; set; }
    public TimeSpan Duration { get; set; }
}

public class TimeSpanConverter : IValueConverter {
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
        return ((TimeSpan)value).ToString("mm\\:ss");
    }
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) {
        throw new NotImplementedException();
    }
}

In case if approach with StringFormat is not working (which should not be the case) you can try approach with Converter (commented in code for Duration column)