Question

I am getting some data from an xml that updates every 2 minutes or so with async WebRequest. So i need everytime the data changes the listbox to change accordingly. I pull the data from the internet and the last lines of code are these.

    IEnumerable<Update> list = from y in xelement.Descendants("Song")
                   select new Update()
                   {
                       NowTitle = y.Attribute("title").Value,
                       NowArtist = y.Element("Artist").Attribute("name").Value
                   };
                   Dispatcher.BeginInvoke(()=> nowList.ItemsSource = list);

XAML looks like this.

     <ListBox x:Name="nowList" Height="86" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Margin="0,0,0,0" Orientation="Vertical" Background="Gray" HorizontalAlignment="Stretch">
                            <TextBlock Height="Auto" Width="480" Text="{Binding Path=NowTitle, Mode=OneWay}" TextWrapping="Wrap" TextAlignment="Center" FontSize="24" FontWeight="Bold" Foreground="#FFE5D623" HorizontalAlignment="Stretch" />
                            <TextBlock Height="Auto" Width="480" Text="{Binding Path=NowArtist, Mode=OneWay}" TextWrapping="Wrap" TextAlignment="Center" FontSize="24" FontWeight="Bold" Foreground="#FFE5D623" HorizontalAlignment="Stretch" />
                        </StackPanel>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>

the class Update that contains the properties is this.

    public class Update : INotifyPropertyChanged
{

    string nowTitle;
    string nowArtist;
    public string NowTitle
    {
        get
        {
            if (!string.IsNullOrEmpty(nowTitle))
            {
                return "Τώρα : " + nowTitle;
            }
            else
            {
                return "something";
            }
        }
        set { this.nowTitle = value;
        NotifyPropertyChanged("NowTitle");
        }
    }
    public string NowArtist
    {
        get
        {
            if (!string.IsNullOrEmpty(nowTitle))
            {
                return "by " + nowArtist;
            }
            else
            {
                return "";
            }
        }
        set { this.nowArtist = value;
        NotifyPropertyChanged("NowArtist");
        }
    }


    #region INotifyPropertyChanged Members
    public event PropertyChangedEventHandler PropertyChanged;
    public void NotifyPropertyChanged(String propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (null != handler)
        {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    #endregion

}

Can anyone tell me what am i doing wrong? thanks!

Answer 1

two things, first, make sure your nowList property is raising property changed events, second, make sure your nowList is of type ObservableCollection< Update >

<edit>

If nowList is your listbox, that is more then likely your culprite. try making an ObservableCollection<Update> as a property that raises change events, and then in your XAML bind your list box to that…

<ListBox ItemSource={Binding myList}/>

I am relatively sure that will fix your problem

</edit>