Question

When my view wants the value of LogoStation, it returns null because my program has not yet executed LoadStation_Completed.

I want my program waits that LoadStation_Completed is executed before continuing.

Thx

public class Infos
{
    #region propriétés

    private DataServiceCollection<SyndicObject> _infosStation;
    public DataServiceCollection<SyndicObject> InfosStation
    {
        get
        {
            return _infosStation;
        }
        set
        {
            _infosStation = value;
        }
    }

    #endregion

    string nameStation;
    public event PropertyChangedEventHandler PropertyChanged;

    public void NotifyPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this,
                new PropertyChangedEventArgs(propertyName));
        }
    }

    private ImageSource _logoStation;
    public ImageSource LogoStation
    {
        get
        {
            return _logoStation;
        }
        set
        {
            _logoStation = value;
            NotifyPropertyChanged("LogoStation");
        }
    }

    public Infos(string station)
    {
        nameStation = station;
        getInfos();
    }

    public void getInfos()
    {
        SyndicationContext service = new SyndicationContext(new Uri("http://test/817bee9d-faf4-4680-9d05-e41c2c90ae5a/"));

        IQueryable<SyndicObject> requete = (from objectSki in service.Objects
                                           where objectSki.NOMSTATION == nameStation
                                           select objectSki);

        Deployment.Current.Dispatcher.BeginInvoke(() =>
        {
            InfosStation = new DataServiceCollection<SyndicObject>();
            InfosStation.LoadCompleted += new EventHandler<LoadCompletedEventArgs>(InfoStation_LoadCompleted);   
            InfosStation.LoadAsync(requete);
        }
        );
    }

    void InfoStation_LoadCompleted(object sender, LoadCompletedEventArgs e)
    {
        LogoStation = new BitmapImage(new Uri(@"http://test/upload/" + InfosStation[0].LOGO, UriKind.Absolute));
    }
}

Answer 1

By using the property setter you are using NotifyPropertyChanged (correctly) to tell the UI bound to LogoStation that it has been updated. This should mean that the UI will display nothing initially and then the image when the load has completed.

Without seeing your view code what you have here looks correct – apart from the fact that your Infos class doesn’t inherit from INotifyPropertyChanged. This means that the event never gets sent.

Update your class definition and you should be good to go.