private void Query_Click(object sender, RoutedEventArgs e) { Query q = new Query() { OutFields = new OutFields() { "*" }, ObjectIDs = new int[] { 78597 }, }; QueryTask qt = new QueryTask("http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/HomelandSecurity/operations/MapServer/2"); qt.DisableClientCaching = true; qt.ExecuteCompleted += new EventHandler<QueryEventArgs>(qt_ExecuteCompleted); qt.ExecuteAsync(q); } void qt_ExecuteCompleted(object sender, QueryEventArgs e) { foreach (var f in e.FeatureSet.Features) System.Diagnostics.Debug.WriteLine(f.Attributes["description"]); } private void FeatureLayer_MouseLeftButtonDown(object sender, GraphicMouseButtonEventArgs e) { //78597 e.Graphic.Attributes["description"] = "this is a test"; }