Getting Exception when trying to retrieve data from "OpenWeatherMap.org"

Question

I am currently working on Weather API in which I am trying to take values from OpenWeatherMap.org. But When I click the button to retrieve the information from the website. It gives me the following Error.Here's the Screenshot of the exception,I am Getting

Also Here's the UI for Button I am clicking. Here's the Screenshot

System.Exception was unhandled by user code
HResult=-2146233088
Message=Exception of type 'System.Exception' was thrown.
Source=UWPWeather
StackTrace:
   at UWPWeather.LocationManager.<GetPosition>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at UWPWeather.MainPage.<Button_Click>d__1.MoveNext()
   InnerException:

The OpenWeatherMapProxy.cs code:

        using System;
        using System.Collections.Generic;
        using System.IO;
        using System.Linq;
        using System.Net.Http;
        using System.Runtime.Serialization;
        using System.Runtime.Serialization.Json;
        using System.Text;
        using System.Threading.Tasks;

        namespace WeatherAPI
        {
        public class OpenWeatherMapProxy
        {
        public async static Task<RootObject>GetWeather(double lat,double lon)

        {

        var http = new HttpClient();

        var response = await http.GetAsync("http://api.openweathermap.org/data/2.5/weather? lat=35&lon=77.20081&appid=b1b15e88fa797225412429c1c50c122a");


        var result = await response.Content.ReadAsStringAsync();

        var serializer = new DataContractJsonSerializer(typeof(RootObject));

        var ms = new MemoryStream(Encoding.UTF8.GetBytes(result));

        var data = (RootObject)serializer.ReadObject(ms);
        return data;

    }

}

public class Coord
{
    [DataMember]
    public double lon { get; set; }
    [DataMember]
    public double lat { get; set; }
}
[DataContract]
public class Weather
{
    [DataMember]
    public int id { get; set; }
    [DataMember]
    public string main { get; set; }
    [DataMember]
    public string description { get; set; }
    [DataMember]
    public string icon { get; set; }
}
[DataContract]
public class Main
{
    [DataMember]
    public double temp { get; set; }
    [DataMember]
    public int pressure { get; set; }
    [DataMember]
    public int humidity { get; set; }
    [DataMember]
    public double temp_min { get; set; }
    [DataMember]
    public double temp_max { get; set; }
}
[DataContract]
public class Wind
{
    [DataMember]
    public double speed { get; set; }
    [DataMember]
    public int deg { get; set; }
}
[DataContract]
public class Clouds
{
    [DataMember]
    public int all { get; set; }
}
[DataContract]
public class Sys
{
    [DataMember]
    public int type { get; set; }
    [DataMember]
    public int id { get; set; }
    [DataMember]
    public double message { get; set; }
    [DataMember]
    public string country { get; set; }
    [DataMember]
    public int sunrise { get; set; }
    [DataMember]
    public int sunset { get; set; }
}
[DataContract]
public class RootObject
{
    [DataMember]
    public Coord coord { get; set; }
    [DataMember]
    public List<Weather> weather { get; set; }
    [DataMember]
    public string @base { get; set; }
    [DataMember]
    public Main main { get; set; }
    [DataMember]
    public Wind wind { get; set; }
    [DataMember]
    public Clouds clouds { get; set; }
    [DataMember]
    public int dt { get; set; }
    [DataMember]
    public Sys sys { get; set; }
    [DataMember]
    public int id { get; set; }
    [DataMember]
    public string name { get; set; }
    [DataMember]
    public int cod { get; set; }
}

MainPage.xaml.cs code:

    using System;
    using System.Collections.Generic;
    using System.IO;
    using System.Linq;
    using System.Runtime.InteropServices.WindowsRuntime;
    using Windows.Foundation;
    using Windows.Foundation.Collections;
    using Windows.UI.Xaml;
    using Windows.UI.Xaml.Controls;
    using Windows.UI.Xaml.Controls.Primitives;
    using Windows.UI.Xaml.Data;
    using Windows.UI.Xaml.Input;
    using Windows.UI.Xaml.Media;
    using Windows.UI.Xaml.Navigation;

    // The Blank Page item template is documented at           http://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409

   namespace WeatherAPI
   {
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class MainPage : Page
{
    public MainPage()
    {
        this.InitializeComponent();
    }

    private async void Button_Click(object sender, RoutedEventArgs e)
    {
        RootObject myWeather = await OpenWeatherMapProxy.GetWeather(20.0,30.0);
        ResultTextBlock.Text = myWeather.name + " - " + ((int)myWeather.main.temp).ToString();
    } 
}

}

score 0 · Answer 1 · answered Mar 21 '16 at 18:02

Here's the code running (it is running a console application):

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    public class OpenWeatherMapProxy
    {
        public async static Task<RootObject> GetWeather(double lat, double lon)

        {

            var http = new HttpClient();

            var response = await http.GetAsync("http://api.openweathermap.org/data/2.5/weather?lat=35&lon=77.20081&appid=b1b15e88fa797225412429c1c50c122a");


            var result = await response.Content.ReadAsStringAsync();

            var serializer = new DataContractJsonSerializer(typeof(RootObject));

            var ms = new MemoryStream(Encoding.UTF8.GetBytes(result));

            var data = (RootObject)serializer.ReadObject(ms);
            return data;

        }
    }


    public class Coord
    {
        [DataMember]
        public double lon { get; set; }
        [DataMember]
        public double lat { get; set; }
    }

    [DataContract]
    public class Weather
    {
        [DataMember]
        public double id { get; set; }
        [DataMember]
        public string main { get; set; }
        [DataMember]
        public string description { get; set; }
        [DataMember]
        public string icon { get; set; }
    }

    [DataContract]
    public class Main
    {
        [DataMember]
        public double temp { get; set; }
        [DataMember]
        public double pressure { get; set; }
        [DataMember]
        public double humidity { get; set; }
        [DataMember]
        public double temp_min { get; set; }
        [DataMember]
        public double temp_max { get; set; }
    }

    [DataContract]
    public class Wind
    {
        [DataMember]
        public double speed { get; set; }
        [DataMember]
        public double deg { get; set; }
    }

    [DataContract]
    public class Clouds
    {
        [DataMember]
        public double all { get; set; }
    }

    [DataContract]
    public class Sys
    {
        [DataMember]
        public double type { get; set; }
        [DataMember]
        public double id { get; set; }
        [DataMember]
        public double message { get; set; }
        [DataMember]
        public string country { get; set; }
        [DataMember]
        public double sunrise { get; set; }
        [DataMember]
        public double sunset { get; set; }
    }

    [DataContract]
    public class RootObject
    {
        [DataMember]
        public Coord coord { get; set; }
        [DataMember]
        public List<Weather> weather { get; set; }
        [DataMember]
        public string @base { get; set; }
        [DataMember]
        public Main main { get; set; }
        [DataMember]
        public Wind wind { get; set; }
        [DataMember]
        public Clouds clouds { get; set; }
        [DataMember]
        public double dt { get; set; }
        [DataMember]
        public Sys sys { get; set; }
        [DataMember]
        public double id { get; set; }
        [DataMember]
        public string name { get; set; }
        [DataMember]
        public double cod { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            RootObject myWeather = Task.Run(() => OpenWeatherMapProxy.GetWeather(20.0, 30.0)).Result;
            Console.WriteLine( myWeather.name + " - " + ((int)myWeather.main.temp).ToString()); 
        }

    }

Yes, all the fields are populated. If you set a breakpoint on the line where you print out the values, you can see all of the values in myWeather. — Pedro G. Dias, Mar 21 '16 at 18:11
Place the cursor on that line, then press F9 to set a breakpoint then run the program :) Once the program stops at the line (marked in yellow) you can hold your mouse pointer over the myWeather variable to inspect it's values — Pedro G. Dias, Mar 21 '16 at 18:14
Ya I did that. I am getting the result as Thang 273.something.. What is Thang? I am sorry for being lil weird at this moment but I didn't get your joke there. :) — Prateek Gogia, Mar 21 '16 at 18:17
Thang is probably the name of the location for which you entered latitude and longitude :) Try changing those to the lat/long of your city and see if it says something different. — Pedro G. Dias, Mar 21 '16 at 18:21
BAM!! My Code is Running. Thanks a lot Mate. You solved my problem. Can i be in touch with you? — Prateek Gogia, Mar 21 '16 at 18:27
Sure, just keep me on your watchlist :) Don't forget to tag the answer as "solved" if you are happy with the reply :) — Pedro G. Dias, Mar 21 '16 at 18:28

score -1 · Accepted Answer · answered Mar 21 '16 at 17:34

-1

((int)myWeather.main.temp).ToString()

I have to ask: Why to int and then back to string again??

Anyways, the answer to your problem:

You need to check that myWeather != null && myWeather.main != null && myWeather.main.temp != null

One of them is null, which is giving you the exception.

answered Mar 21 '16 at 17:34

Pedro G. Dias

3,058
1
12
25

I've checked again and No! Nothing is Null. I've provided the code. Can you please have a look? – Prateek Gogia Mar 21 '16 at 17:44
*Something* **must** be null or you would not get the exception! @PrateekGogia – Ňɏssa Pøngjǣrdenlarp Mar 21 '16 at 17:50
@Plutonix Man I checked the whole damn code! But I didn't find anything. Can you please help? – Prateek Gogia Mar 21 '16 at 17:52
I ran it from here, and got the follwing error: The value '592.56' cannot be parsed as the type 'Int32'. So it's probably just your deserialization that you need to overlook. Check the inner exceptions to see the error messages and you should have it solved in a jiffy :) – Pedro G. Dias Mar 21 '16 at 17:54
Hey! Actually got to know something now. I tried to change the value and it is saying that error CS0029: Cannot implicitly convert type 'int' to WeatherAPI.main – Prateek Gogia Mar 21 '16 at 17:54
I replaced all "int" with "double" and now it runs :) It says "Thang 253".. Not Pootie Tang I hope :D Don't forget to tag the answer as "answered" if you're happy :) – Pedro G. Dias Mar 21 '16 at 17:57
Can you send the screenshot please? – Prateek Gogia Mar 21 '16 at 18:00
Screenshot of what? The code or the program running? – Pedro G. Dias Mar 21 '16 at 18:01
The Code. I am just a beginner sir. I am learning from Bob Tabor's Training videos. So i need the code to understand. :) – Prateek Gogia Mar 21 '16 at 18:03
Bob Tabor is a fantastic trainer. I am actually translating all of his videos into Norwegian :) Working on the UWP for beginners series, so far I've made 15 episodes only :) – Pedro G. Dias Mar 21 '16 at 18:05
I don't understand everything he teaches but ya definitely,He's Awesome! – Prateek Gogia Mar 21 '16 at 18:09
@PedroG.Dias I've sent you the request of connecting on LinkedIn. Please do check out. :) – Prateek Gogia May 13 '16 at 09:06

Getting Exception when trying to retrieve data from "OpenWeatherMap.org"

2 Answers2