How to call the Spotify API from C#

Question

I'm trying to call the spotify API with C#. Unfortunately, I'm already stuck with getting the access token

This is how I tried to get it:

private static async Task<string> GetAccessToken()
        {
            SpotifyToken token = new SpotifyToken();

            string postString = string.Format("grant_type=client_credentials");
            byte[] byteArray = Encoding.UTF8.GetBytes(postString);

            string url = "https://accounts.spotify.com/api/token";

            WebRequest request = WebRequest.Create(url);
            request.Method = "POST";
            request.Headers.Add("Authorization", "Basic {Encoded myClientIdXXX:myAppSecretYYY}");
            request.ContentType = "application/x-www-form-urlencoded";
            request.ContentLength = byteArray.Length;
            using (Stream dataStream = request.GetRequestStream())
            {
                dataStream.Write(byteArray, 0, byteArray.Length);
                using (WebResponse response = await request.GetResponseAsync())
                {
                    using (Stream responseStream = response.GetResponseStream())
                    {
                        using (StreamReader reader = new StreamReader(responseStream))
                        {
                            string responseFromServer = reader.ReadToEnd();
                            token = JsonConvert.DeserializeObject<SpotifyToken>(responseFromServer);
                        }
                    }
                }
            }
            return token.access_token;
        }

But I get an error:

Der Remoteserver hat einen Fehler zurückgegeben: (400) Ungültige Anforderung.

Which translates to:

The remote server returned an error: (400) Bad Request.

What am I doing wrong here? I've registered my app at spotify and set the clientId and secret in the request header...

Thanks in advance

Answer 1

Spotify API from C#

public string GetAccessToken()
    {
            SpotifyToken token = new SpotifyToken();
            string url5 = "https://accounts.spotify.com/api/token";
            var clientid = "your_client_id";
            var clientsecret = "your_client_secret";

            //request to get the access token
            var encode_clientid_clientsecret = Convert.ToBase64String(Encoding.UTF8.GetBytes(string.Format("{0}:{1}", clientid, clientsecret)));

            HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(url5);

            webRequest.Method = "POST";
            webRequest.ContentType = "application/x-www-form-urlencoded";
            webRequest.Accept = "application/json";
            webRequest.Headers.Add("Authorization: Basic " + encode_clientid_clientsecret);

            var request = ("grant_type=client_credentials");
            byte[] req_bytes = Encoding.ASCII.GetBytes(request);
            webRequest.ContentLength = req_bytes.Length;

            Stream strm = webRequest.GetRequestStream();
            strm.Write(req_bytes, 0, req_bytes.Length);
            strm.Close();

            HttpWebResponse resp = (HttpWebResponse)webRequest.GetResponse();
            String json = "";
            using (Stream respStr = resp.GetResponseStream())
            {
                using (StreamReader rdr = new StreamReader(respStr, Encoding.UTF8))
                {
                    //should get back a string i can then turn to json and parse for accesstoken
                    json = rdr.ReadToEnd();
                    rdr.Close();
                }
            }
     return token.access_token;
}

Answer 2

Do you really need to write your own client from scratch building WebRequests, etc.? Why not use an existing client like SpotifyAPI-NET?

Anyway, you can see how they do it, on GitHub:

https://github.com/JohnnyCrazy/SpotifyAPI-NET/blob/master/SpotifyAPI/Web/Auth/AutorizationCodeAuth.cs

using Newtonsoft.Json;
using SpotifyAPI.Web.Enums;
using SpotifyAPI.Web.Models;
using System;
using System.Collections.Specialized;
using System.Diagnostics;
using System.IO;
using System.Net;
using System.Text;
using System.Threading;

namespace SpotifyAPI.Web.Auth
{
    public class AutorizationCodeAuth
    {
        public delegate void OnResponseReceived(AutorizationCodeAuthResponse response);

        private SimpleHttpServer _httpServer;
        private Thread _httpThread;
        public String ClientId { get; set; }
        public String RedirectUri { get; set; }
        public String State { get; set; }
        public Scope Scope { get; set; }
        public Boolean ShowDialog { get; set; }

        /// <summary>
        ///     Will be fired once the user authenticated
        /// </summary>
        public event OnResponseReceived OnResponseReceivedEvent;

        /// <summary>
        ///     Start the auth process (Make sure the internal HTTP-Server ist started)
        /// </summary>
        public void DoAuth()
        {
            String uri = GetUri();
            Process.Start(uri);
        }

        /// <summary>
        ///     Refreshes auth by providing the clientsecret (Don't use this if you're on a client)
        /// </summary>
        /// <param name="refreshToken">The refresh-token of the earlier gathered token</param>
        /// <param name="clientSecret">Your Client-Secret, don't provide it if this is running on a client!</param>
        public Token RefreshToken(string refreshToken, string clientSecret)
        {
            using (WebClient wc = new WebClient())
            {
                wc.Proxy = null;
                wc.Headers.Add("Authorization",
                    "Basic " + Convert.ToBase64String(Encoding.UTF8.GetBytes(ClientId + ":" + clientSecret)));
                NameValueCollection col = new NameValueCollection
                {
                    {"grant_type", "refresh_token"},
                    {"refresh_token", refreshToken}
                };

                String response;
                try
                {
                    byte[] data = wc.UploadValues("https://accounts.spotify.com/api/token", "POST", col);
                    response = Encoding.UTF8.GetString(data);
                }
                catch (WebException e)
                {
                    using (StreamReader reader = new StreamReader(e.Response.GetResponseStream()))
                    {
                        response = reader.ReadToEnd();
                    }
                }
                return JsonConvert.DeserializeObject<Token>(response);
            }
        }

        private String GetUri()
        {
            StringBuilder builder = new StringBuilder("https://accounts.spotify.com/authorize/?");
            builder.Append("client_id=" + ClientId);
            builder.Append("&response_type=code");
            builder.Append("&redirect_uri=" + RedirectUri);
            builder.Append("&state=" + State);
            builder.Append("&scope=" + Scope.GetStringAttribute(" "));
            builder.Append("&show_dialog=" + ShowDialog);
            return builder.ToString();
        }

        /// <summary>
        ///     Start the internal HTTP-Server
        /// </summary>
        public void StartHttpServer(int port = 80)
        {
            _httpServer = new SimpleHttpServer(port, AuthType.Authorization);
            _httpServer.OnAuth += HttpServerOnOnAuth;

            _httpThread = new Thread(_httpServer.Listen);
            _httpThread.Start();
        }

        private void HttpServerOnOnAuth(AuthEventArgs e)
        {
            OnResponseReceivedEvent?.Invoke(new AutorizationCodeAuthResponse()
            {
                Code = e.Code,
                State = e.State,
                Error = e.Error
            });
        }

        /// <summary>
        ///     This will stop the internal HTTP-Server (Should be called after you got the Token)
        /// </summary>
        public void StopHttpServer()
        {
            _httpServer = null;
        }

        /// <summary>
        ///     Exchange a code for a Token (Don't use this if you're on a client)
        /// </summary>
        /// <param name="code">The gathered code from the response</param>
        /// <param name="clientSecret">Your Client-Secret, don't provide it if this is running on a client!</param>
        /// <returns></returns>
        public Token ExchangeAuthCode(String code, String clientSecret)
        {
            using (WebClient wc = new WebClient())
            {
                wc.Proxy = null;

                NameValueCollection col = new NameValueCollection
                {
                    {"grant_type", "authorization_code"},
                    {"code", code},
                    {"redirect_uri", RedirectUri},
                    {"client_id", ClientId},
                    {"client_secret", clientSecret}
                };

                String response;
                try
                {
                    byte[] data = wc.UploadValues("https://accounts.spotify.com/api/token", "POST", col);
                    response = Encoding.UTF8.GetString(data);
                }
                catch (WebException e)
                {
                    using (StreamReader reader = new StreamReader(e.Response.GetResponseStream()))
                    {
                        response = reader.ReadToEnd();
                    }
                }
                return JsonConvert.DeserializeObject<Token>(response);
            }
        }
    }

    public struct AutorizationCodeAuthResponse
    {
        public String Code { get; set; }
        public String State { get; set; }
        public String Error { get; set; }
    }
}