Spotify Community

Nogaruki · 2021-03-17

Hello, I have created an API in ASP.NET Framework 4.5, and an html page using ajax communicating with the API. My problem is that I don't know how to communicate with Spotify to get the login page and display it to the user, knowing that the html page is independent (not in the solution)

C# code that allows to retrieve a token :

HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create("https://accounts.spotify.com/api/authorize");

                webRequest.Method = "POST";
                webRequest.ContentType = "application/x-www-form-urlencoded";
                webRequest.Accept = "application/json";

                var request = ("grant_type=client_credentials&client_id=" + ClientId + "&client_secret=" + ClientSecret+ "&scope=playlist-read-private");
                byte[] reqBytes = Encoding.ASCII.GetBytes(request);
                webRequest.ContentLength = reqBytes.Length;

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

                try
                {
                    HttpWebResponse resp = (HttpWebResponse)webRequest.GetResponse();
                    String Result = "";
                    using (Stream respStr = resp.GetResponseStream())
                    {
                        using (StreamReader rdr = new StreamReader(respStr, Encoding.UTF8))
                        {
                            //retourne un string
                            Result = rdr.ReadToEnd();
                            rdr.Close();

                            JsonValue Json = JsonValue.Parse(Result);
                            _instance._accessToken = Json["access_token"];
                            _instance._expiresIn = Json["expires_in"];
                            _instance._tokenType = Json["token_type"];
                        }
                    }
                }

JQuery AJAX :

 $("#connection").click(function()
    {
        var Data = { Name: "GetUserPlaylist" };
        $.ajax({
            url: 'https://localhost:44376/SpotifyDrag_Drop/Index',
            type: 'POST',
            contentType: 'application/json; charset=UTF-8',
            crossDomain: true,
            dataType: 'JSON',
            data: JSON.stringify(Data),
            success: function(response)
            {
                console.log("conneciton sucess");
                viewPlayList(response);
            },
            error: function(xhr)
            {
                console.log("Error: " + xhr.statusText);
            }
        });
    });

Plan

Premium

Country

France

Device

PC

Operating System

Windows 10

Okay I change some paramerts :

var plainTextBytes = System.Convert.FromBase64String(ClientId);
                string base64 = System.Text.Encoding.UTF8.GetString(plainTextBytes);
                HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create("https://accounts.spotify.com/authorize?" +
                    "client_id=" + ClientId + "&response_type=code&redirect_uri=http://spotifydragdrop&scope=playlist-read-private");

                webRequest.Method = "GET";
                webRequest.ContentType = "application/x-www-form-urlencoded";
                webRequest.Accept = "*/*";

Now i receive and html page :

Result

"\n<!DOCTYPE html>\n<html id=\"app\" lang=\"fr\" dir=\"ltr\" ng-csp ng-strict-di>\n<head>\n <meta charset=\"utf-8\">\n <title ng-bind=\"('loginTitle' | localize) + ' - Spotify'\">Spotify</title>\n <meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no\">\n <base href=\"/\">\n <link rel=\"icon\" href=\"https://accounts.scdn.co/sso/images/favicon.ace4d8543bbb017893402a1e9d1ac1fa.ico\">\n <link href=\"https://accounts.scdn.co/sso/css/index.7f5ebce98590aa1e70ff.css\" media=\"screen\" rel=\"stylesheet\">\n\n <script defer src=\"https://accounts.scdn.co/sso/js/index.7f5ebce98590aa1e70ff.js\" sp-bootstrap></script>\n <meta ng-non-bindable sp-bootstrap-data='{\"phoneFeatureEnabled\":false,\"previewEnabled\":false,\"user\":false,\"tpaState\":\"AQD+OgdYnOEkdSlhAICFXJmGmNPccw0clGNjRXSfDoYkukertPlUhCluiz+fHJZJ6iglgGqPnQ7US0ZZvlMmKOUiA71ZfNTUUDtE5sYVS0adYlFPT3FcVFv4R4vbvJDuPD4dEC/o22uy/iRYAIMZRSCNFpwzeY7eyOld0Mc8KamS7pcmrMXcV44N/6b4p4Sh8fW/dIDNloji2f1VdLS6KtZc1rezDC/2AKngdTYCWwdQlh3e4+6kf5ZphA4EkDWqMVnUxIgJnb9yh2kid19Qt8umTlPDRtXhimQwlZrP7LD866Ls+cNwXG/nA/ck8oBokvrB2jD1bqRXZNZ1m2DbVYtOtDqXZAejBc+A5NtgxyFWpq+Vld411rvYTqbjOehDCuhWy7h0mwkJ13icBc6XrnjodhDw4Kc5GBXMnzVvdCaw\",\"BON\":[\"0\",\"0\",-1482864988]}'>\n</head>\n<body ng-controller=\"LoginController\">\n <div ng-include=\"template\"></div>\n</body>\n</html>\n"

string

By the way, I have to know that I am in a singleton class so I return a token object with this method, so I don't see how to return the html page ?
With an await ?

Nogaruki · 2021-03-17

UPDATE : i change my var request to
var request = ("client_id=" + ClientId + "&response_type=code&redirect_uri=http://spotifydragdrop/login&scope=playlist-read-private");

tobikabla · 2021-03-26

Hi,
I don't think you can do this part on the server side.

You should open the webpage `https://accounts.spotify.com/api/authorize?client_id=ClientId&response_type=code&redirect_uri=http:/...` and let the user confirm or enter his credentials.

You will then receive the code in the query params of the callback uri that you sent to spotify. So in your web app (http://spotifydragdrop/login) you have to listen to the query params:

document.addEventListener('DOMContentLoaded', function (event) {
        console.log('loaded');
        const urlParams = new URLSearchParams(location.search);
        const code = urlParams.get('code') || null;

// now you have to exchange the code for an access token

      });

Then you exchange this code for a access token with your .NET backend.

Hope this helps.

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