从ListView SelectedItem传递JSON对象数据

Question

I need some help with passing the ListView Tapped Id (which I get from a json).

I populate the listView with an API call to a server:

        private async void searchButton_Click(object sender, RoutedEventArgs e)
    {
        var textFrom = odTextBox.Text;
        var textTo = doTextBox.Text;
        var searchResult = await PrevoziApi.SearchRidesAsync(textFrom, textTo, datePicker.Date.UtcDateTime);
        var array = searchResult.CarshareList
                .OrderBy(cs => cs.Time)
                .Select(cs => cs.Contact + " " + cs.Time)
                .ToArray();
            listView.ItemsSource = array;
    }

Now, when I click on an item of listView, I want to navigate to another page(CarShareDetailedPage) and make another call to the API, to get more detailed data about that item. So I need to pass the selectedItem id from one page to other. How do I do that ?

I'm navigating to another page like this:

        private void listView_Tapped(object sender, TappedRoutedEventArgs e)
    {
        Frame.Navigate(typeof(CarShareDetailedPage), listView.SelectedIndex);
    }

The OnNagiatedMethod on that page is:

        protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        var value = e.ToString();
        carShareTextBox.Text = value;
    }

And my json class is:

public class CarshareList
    {
        [JsonProperty("id")]
        public int Id { get; set; }
        [JsonProperty("type")]
        public string Type { get; set; }
        [JsonProperty("from_id")]
        public string FromId { get; set; }
        [JsonProperty("from_country")]
        public string FromCountry { get; set; }
        [JsonProperty("from_country_name")]
        public string FromCountryName { get; set; }
        [JsonProperty("to_id")]
        public string ToId { get; set; }
        [JsonProperty("to")]
        public string To { get; set; }
        [JsonProperty("to_country")]
        public string ToCountry { get; set; }
        [JsonProperty("to_country_name")]
        public string ToCountryName { get; set; }
        [JsonProperty("time")]
        public string Time { get; set; }
        [JsonProperty("date_iso8601")]
        public DateTime DateIso8601 { get; set; }
        [JsonProperty("added")]
        public DateTime Added { get; set; }
        [JsonProperty("price")]
        public double? Price { get; set; }
        [JsonProperty("num_people")]
        public double NumPeople { get; set; }
        [JsonProperty("author")]
        public string Author { get; set; }
        [JsonProperty("is_author")]
        public string IsAuthor { get; set; }
        [JsonProperty("comment")]
        public string Comment { get; set; }
        [JsonProperty("contact")]
        public string Contact { get; set; }
        [JsonProperty("date")]
        public string Date { get; set; }
        [JsonProperty("full")]
        public string Full { get; set; }
        [JsonProperty("insured")]
        public string Insured { get; set; }
        [JsonProperty("share_type")]
        public string ShareType { get; set; }
        [JsonProperty("confirmed_contact")]
        public string ConfirmedContact { get; set; }
        [JsonProperty("bookmark")]
        public object Bookmark { get; set; }
        [JsonProperty("from")]
        public string From { get; set; }
    }

    public class CarshareResponse
    {
        [JsonProperty("search_type")]
        public string SearchType { get; set; }
        [JsonProperty("carshare_list")]
        public IList<CarshareList> CarshareList { get; set; }
    }

Let me say this is the first time ever I'm doing any work with Apis and json. Thanks for your help!

EDIT: I added the code for the API below, so this now should be all the code I have.

public class PrevoziApi
{ public static async Task<CarshareResponse> SearchRidesAsync(
    string fromCity, 
    string toCity, 
    DateTime date, 
    string type = "shares", 
    CancellationToken token = default(CancellationToken))
    {
        using (var client = new RestClient("https://prevoz.org/api/"))
        {
                var request = new RestRequest("search/" + type + "/", HttpMethod.Get);
                request.AddQueryParameter("f", fromCity);
                request.AddQueryParameter("fc", "SI");
                request.AddQueryParameter("t", toCity);
                request.AddQueryParameter("tc", "SI");
                request.AddQueryParameter("d", date.ToString("yyyy-MM-dd"));
                request.AddQueryParameter("exact", "true");
                return
                    (await client.Execute<CarshareResponse>(request, token)).Data;
            }
    }
}

Answer 1

So with this, you are ordering by the time but displaying a string only that says "[Contact] [Time]". This in-and-of-itself does not hold any relation to the JSON that was returned from your search method. What you'll want to do is instead of making it an array, instead making a List<> object that can store some additional "background" data about that request to send off.

This will require a bit more effort though on your end. You will want to create a class

public class CarItemView {
    public string DisplayText {get; set;}
    public int ID {get; set;}
}

and fill it with whatever data you want to pass along. Then in your filtering you would do:

List<CarItemView> array = searchResult.CarshareList
            .OrderBy(cs => cs.Time)
            .Select(cs => new { DisplayText = cs.Contact + " " + cs.Time, ID = cs.Id}).ToList();

You will then, in your XAML, have to add a template to your listview for display. (Note, this is a real rough outline for a XAML Template)

<ListView>
    <ListView.ItemTemplate>
        <DataTemplate>
            <StackPanel>
                <TextBlock Text="{Binding DisplayText}" />
            </StackPanel>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

NOW when you get your selected item changed event fired, you can handle it and get the ID.

private void listView_Tapped(object sender, TappedRoutedEventArgs e)
{
    var obj = (CarItemView) listView.SelectedItem; // convert item to our new class
    Frame.Navigate(typeof(CarShareDetailedPage), obj.Id.ToString()); // send ID as string
}

Then for the receiving page:

protected override void OnNavigatedTo(NavigationEventArgs e)
{
    var value = e.ToString();
    carShareTextBox.Text = value; // will show the ID number

    var caritemret = /* write a new restful function to return based on ID */
}

UPDATE: This answer was updated from original to reflect the use of an array instead of a list<> object

I hope this helps!

Answer 2

This works:

        private async void searchButton_Click(object sender, RoutedEventArgs e)
    {
        var textFrom = odTextBox.Text;
        var textTo = doTextBox.Text;
        var searchResult = await PrevoziApi.SearchRidesAsync(textFrom, textTo, datePicker.Date.UtcDateTime);

        List<CarItemView> array = searchResult.CarshareList
                                  .OrderBy(cs => cs.Time)
                                  .Select(cs => new CarItemView { DisplayText = cs.Contact + " " + cs.Time, Id = cs.Id })
                                  .ToList();
        listView.ItemsSource = array;
    }

        private void listView_Tapped(object sender, Windows.UI.Xaml.Input.TappedRoutedEventArgs e)
    {
        var obj = (CarItemView)listView.SelectedItem; // convert item to our new class
        Frame.Navigate(typeof(CarShareDetailedPage), obj.Id); // send ID as string        
    }

And on navigated to method on the destination page:

    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        var value = e.Parameter.ToString();
        carShareTextBox.Text = value; // will show the ID number

        /* write a new restful function to return based on ID */
    }

Thanks @daniel, it was mostly as you suggested, with a few errors, but with the help of some guys at the c# chat channel I managed. Thanks to all.