How to get data from json api with c# using httpwebrequest?

Question

I want to get all variables from https://api.coinmarketcap.com/v1/ticker/ in my c# console application. How can I do this?

I started with getting the whole page as a stream. What to do now?

private static void start_get()
{
    HttpWebRequest WebReq = (HttpWebRequest)WebRequest.Create
        (string.Format("https://api.coinmarketcap.com/v1/ticker/"));

    WebReq.Method = "GET";

    HttpWebResponse WebResp = (HttpWebResponse)WebReq.GetResponse();

    Console.WriteLine(WebResp.StatusCode);
    Console.WriteLine(WebResp.Server);

    Stream Answer = WebResp.GetResponseStream();
    StreamReader _Answer = new StreamReader(Answer);
    Console.WriteLine(_Answer.ReadToEnd());
}

What do you want, a string containing information or an object representation of that json result? — ColinM
– ColinM, Commented Jun 27, 2017 at 8:39
check out: stackoverflow.com/questions/8270464/… there are a couple of answers that should get you up and running — MattjeS
– MattjeS, Commented Jun 27, 2017 at 8:39
Possible duplicate of Best way to call a JSON WebService from a .NET Console — Nasreddine
– Nasreddine, Commented Jun 27, 2017 at 8:41

Keyur PATEL · Accepted Answer · 2017-06-27 08:51:51Z

First you need a custom class to use for deserialization:

public class Item
{
    public string id { get; set; }
    public string name { get; set; }
    public string symbol { get; set; }
    public string rank { get; set; }
    public string price_usd { get; set; }
    [JsonProperty(PropertyName = "24h_volume_usd")]   //since in c# variable names cannot begin with a number, you will need to use an alternate name to deserialize
    public string volume_usd_24h { get; set; }
    public string market_cap_usd { get; set; }
    public string available_supply { get; set; }
    public string total_supply { get; set; }
    public string percent_change_1h { get; set; }
    public string percent_change_24h { get; set; }
    public string percent_change_7d { get; set; }
    public string last_updated { get; set; }
}

Next, you can use Newtonsoft Json, a free JSON serialization and deserialization framework in the following way to get your items (include the following using statements):

using System.Net;
using System.IO;
using Newtonsoft.Json;

private static void start_get()
{
    HttpWebRequest WebReq = (HttpWebRequest)WebRequest.Create(string.Format("https://api.coinmarketcap.com/v1/ticker/"));

    WebReq.Method = "GET";

    HttpWebResponse WebResp = (HttpWebResponse)WebReq.GetResponse();

    Console.WriteLine(WebResp.StatusCode);
    Console.WriteLine(WebResp.Server);

    string jsonString;
    using (Stream stream = WebResp.GetResponseStream())   //modified from your code since the using statement disposes the stream automatically when done
    {
       StreamReader reader = new StreamReader(stream, System.Text.Encoding.UTF8);
       jsonString = reader.ReadToEnd();
    }

    List<Item> items = JsonConvert.DeserializeObject<List<Item>>(jsonString);

    Console.WriteLine(items.Count);     //returns 921, the number of items on that page
}

Finally, the list of elements is stored in items.

Draken · Accepted Answer · 2019-09-20 09:01:15Z

3

A simplified version of Keyur PATEL's work.

static void GetCoinValues()
{
    string json = new WebClient().DownloadString("https://api.coinmarketcap.com/v1/ticker/");

    List<Item> items = JsonConvert.DeserializeObject<List<Item>>(json);

    foreach (var item in items)
    {
        Console.WriteLine("ID: " + item.id.ToUpper());
        Console.WriteLine("Name: " + item.name.ToUpper());
        Console.WriteLine("Symbol: " + item.symbol.ToUpper());
        Console.WriteLine("Rank: " + item.rank.ToUpper());
        Console.WriteLine("Price (USD): " + item.price_usd.ToUpper());
        Console.WriteLine("\n");
    }
}

edited Sep 20, 2019 at 9:01

Draken

3,19614 gold badges38 silver badges56 bronze badges

answered Jan 4, 2018 at 21:43

agleno

4781 gold badge6 silver badges20 bronze badges

4 Comments

goodfella Over a year ago

How would you get the data for a specific symbol using your method? I added IF (item.symbol = mySymbol) { set some variables} in the loop but it doesnt return anything.

goodfella Over a year ago

Nevermind I got it figured out...had a problem with case matching so I had to uppercase my string. However the json request seems to limit the list. Not giving the full list of currencies. Anyway to solve around this?

aaron lilly Over a year ago

can i persuade you to shar eyour github repo of this?

Mmm Over a year ago

Note that WebClient implements IDisposable and should have Using or is otherwise disposed.

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