Update binding/staticresource in Windows Phone

Question

In my xaml code I added my class "Feed" to my resources. Like this:

<Page.Resources>
    <data:Feed x:Key="Feed"></data:Feed>
</Page.Resources>

The class contains the property Apod and a method that later updates the property.

private ApodModel _apod;
public ApodModel Apod
{
    get { return _apod; }
    set { _apod = value; }
}
public Feed()
{
    DownloadApod();
}
private async void DownloadApod()
{
    try
    {
        using (HttpClient client = new HttpClient())
        {
            HttpResponseMessage response = await client.GetAsync(new Uri("http://spacehub.azurewebsites.net/api/apod", UriKind.Absolute));
            if (response.IsSuccessStatusCode)
            {
                string json = await response.Content.ReadAsStringAsync();
                Apod = JsonConvert.DeserializeObject<ApodModel>(json);
                var apod = new AppSettings<ApodModel>();
                await apod.SaveAsync("Apod", Apod);
            }
        }
    }
    catch (Exception)
    {
    }
}

In my XAML my binding to the property looks like this:

<StackPanel DataContext="{StaticResource Feed}">
    <TextBlock Text="{Binding Apod.Description}">
</StackPanel>

When I debug the property Apod gets updated but it doesn't change in the XAML. What am I doing wrong?

Answer 1

You need to notify the view when the "Apod" property changes (otherwise, it will read the property value initially as its default value null , and never again). To do this, have your "Feed" class implement INotifyPropertyChanged , and raise the PropertyChanged event in the "Apod" property setter.

Answer 2

You need to use implement your class using INotifyPropertyChange

and them implement interface.

private ApodModel _apod;
public ApodModel Apod
{
    get { return _apod; }
    set { _apod = value; 
          NotifyPropertyChange("Apod");
        }
}

public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChange(string name)
{
    if(PropertyChanged!=null)
    {
        PropertyChanged(this,new PropertyChangedEventArgs(name));
    }
}