c# Example for Location API

Form1.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Web;
using System.Net;
using System.IO;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System.Collections;

namespace locationApi
{
    public partial class Form1 : Form
    {
        ArrayList cities_id = new ArrayList();
        ArrayList districts_id = new ArrayList();
        ArrayList regions_id = new ArrayList();
        
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            string responseFromServer = pigonLocationApi("http://pigon.ws/location/cities");
            List<Query> cities = (List<Query>)JsonConvert.DeserializeObject(responseFromServer, typeof(List<Query>)); 
            foreach (Query obj in cities)
            {
                comboBox1.Items.Add(obj.name);
                cities_id.Add(obj.id);
            }
        }

        public string pigonLocationApi(string Url)
        {
            string requestUri = String.Format(Url);
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(requestUri);
            Stream dataStream;
            WebResponse response = request.GetResponse();
            dataStream = response.GetResponseStream();
            StreamReader reader = new StreamReader(dataStream);
            string responseFromServer = reader.ReadToEnd();
            reader.Close();
            dataStream.Close();
            response.Close();
            return responseFromServer;
        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            districts_id.Clear();
            comboBox2.Items.Clear();
            regions_id.Clear();
            comboBox3.Items.Clear();
            int cityId = int.Parse(cities_id[comboBox1.SelectedIndex].ToString());
            string responseFromServer = pigonLocationApi("http://pigon.ws/location/districts?city_id=" + cityId);
            List<Query> districts = (List<Query>)JsonConvert.DeserializeObject(responseFromServer, typeof(List<Query>));
            foreach (Query obj in districts)
            {
                comboBox2.Items.Add(obj.name);
                districts_id.Add(obj.id);
            }
        }

        private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
            regions_id.Clear();
            comboBox3.Items.Clear();
            int districtId = int.Parse(districts_id[comboBox2.SelectedIndex].ToString());
            string responseFromServer = pigonLocationApi("http://pigon.ws/location/regions?district_id=" + districtId);
            List<Query> regions = (List<Query>)JsonConvert.DeserializeObject(responseFromServer, typeof(List<Query>));
            foreach (Query obj in regions)
            {
                comboBox3.Items.Add(obj.name);
                regions_id.Add(obj.id);
            }
        }

        private void comboBox3_SelectedIndexChanged(object sender, EventArgs e)
        { 
            comboBox4.Items.Clear();
            int regionId = int.Parse(regions_id[comboBox3.SelectedIndex].ToString());
            string responseFromServer = pigonLocationApi("http://pigon.ws/location/streets?region_id=" + regionId);
            List<Query> streets = (List<Query>)JsonConvert.DeserializeObject(responseFromServer, typeof(List<Query>));
            foreach (Query obj in streets)
            {
                comboBox4.Items.Add(obj.name);
            }
        }
    }
}