/// <summary>
        /// Populates the page with content passed during navigation.  Any saved state is also
        /// provided when recreating a page from a prior session.
        /// </summary>
        /// <param name="sender">
        /// The source of the event; typically <see cref="NavigationHelper"/>
        /// </param>
        /// <param name="e">Event data that provides both the navigation parameter passed to
        /// <see cref="Frame.Navigate(Type, Object)"/> when this page was initially requested and
        /// a dictionary of state preserved by this page during an earlier
        /// session.  The state will be null the first time a page is visited.</param>
        private async void NavigationHelper_LoadState(object sender, LoadStateEventArgs e)
        {
            this.pageMode = ((EditObject)(e.NavigationParameter)).pageMode;
            int  raceId = ((EditObject)(e.NavigationParameter)).Id;
            Race race   = new Race();

            if (pageMode == HelperClass.PageMode.Edit)
            {
                PageTitle.Text = "Edit Race";
            }

            if (pageMode == HelperClass.PageMode.Edit)
            {
                race = await SampleDataSource.GetRaceAsync(raceId.ToString());
            }

            var drivers = await SampleDataSource.GetItemsAsync();

            race.Drivers = drivers.ToList();

            this.DefaultViewModel["Race"] = race;

            // get drivers to fill combos
            //var drivers = await SampleDataSource.GetItemsAsync();
            //this.defaultViewModel["Drivers"] = drivers;
        }
        /// <summary>
        /// Populates the page with content passed during navigation.  Any saved state is also
        /// provided when recreating a page from a prior session.
        /// </summary>
        /// <param name="sender">
        /// The source of the event; typically <see cref="NavigationHelper"/>
        /// </param>
        /// <param name="e">Event data that provides both the navigation parameter passed to
        /// <see cref="Frame.Navigate(Type, object)"/> when this page was initially requested and
        /// a dictionary of state preserved by this page during an earlier
        /// session.  The state will be null the first time a page is visited.</param>
        private async void NavigationHelper_LoadState(object sender, LoadStateEventArgs e)
        {
            var drivers = await SampleDataSource.GetItemsAsync();

            this.DefaultViewModel["Drivers"] = drivers;

            var races = await SampleDataSource.GetRacesAsync();

            this.DefaultViewModel["Races"] = races;
        }
        /// <summary>
        /// Populates the page with content passed during navigation.  Any saved state is also
        /// provided when recreating a page from a prior session.
        /// </summary>
        /// <param name="sender">
        /// The source of the event; typically <see cref="NavigationHelper"/>
        /// </param>
        /// <param name="e">Event data that provides both the navigation parameter passed to
        /// <see cref="Frame.Navigate(Type, Object)"/> when this page was initially requested and
        /// a dictionary of state preserved by this page during an earlier
        /// session.  The state will be null the first time a page is visited.</param>
        private async void navigationHelper_LoadState(object sender, LoadStateEventArgs e)
        {
            var items = await SampleDataSource.GetItemsAsync();

            this.DefaultViewModel["ContentList"] = items;
        }