Spotify.NET/SpotifyAPI.Docs/docs/authorization_code.md

id	title
authorization_code	Authorization Code

This flow is suitable for long-running applications in which the user grants permission only once. It provides an access token that can be refreshed. Since the token exchange involves sending your secret key, perform this on a secure location, like a backend service, and not from a client such as a browser or from a mobile app.

Existing Web-Server

If you are already in control of a Web-Server (like ASP.NET), you can start the flow by generating a login uri

// Make sure "http://localhost:5000" is in your applications redirect URIs!
var loginRequest = new LoginRequest(
  new Uri("http://localhost:5000"),
  "ClientId",
  LoginRequest.ResponseType.Code
)
{
  Scope = new[] { Scopes.PlaylistReadPrivate, Scopes.PlaylistReadCollaborative }
};
var uri = loginRequest.ToUri();
// Redirect user to uri via your favorite web-server

When the user is redirected to the generated uri, he will have to login with his spotify account and confirm, that your application wants to access his user data. Once confirmed, he will be redirect to http://localhost:5000 and a code parameter is attached to the query. This code has to be exchanged for an access_token and refresh_token:

// This method should be called from your web-server when the user visits "http://localhost:5000"
public Task GetCallback(string code)
{
  var response = await new OAuthClient().RequestToken(
    new AuthorizationCodeTokenRequest("ClientId", "ClientSecret", code, "http://localhost:5000")
  );

  var spotify = new SpotifyClient(response.AccessToken);
  // Also important for later: response.RefreshToken
}

If the token expires at some point (check via response.IsExpired), you can refresh it:

var newResponse = await new OAuthClient().RequestToken(
  new AuthorizationCodeRefreshRequest("ClientId", "ClientSecret", response.RefreshToken)
);

var spotify = new SpotifyClient(newResponse.AccessToken);

You can also let the AuthorizationCodeAuthenticator take care of the refresh part:

var response = await new OAuthClient().RequestToken(
  new AuthorizationCodeTokenRequest("ClientId", "ClientSecret", code, "http://localhost:5000")
);
var config = SpotifyClientConfig
  .CreateDefault()
  .WithAuthenticator(new AuthorizationCodeAuthenticator("ClientId", "ClientSecret", response));

var spotify = new SpotifyClient(config);

For a real example, have a look at Example.ASP. This also uses the great package AspNet.Security.OAuth.Spotify which takes care of the OAuth flow inside of ASP.NET.

Using Spotify.Web.Auth

For cross-platform CLI and desktop apps (non UWP apps), Spotify.Web.Auth can be used to supply a small embedded Web Server for the code retrieval.

:::warning You're client secret will be exposed when embedded in a desktop/cli app. This can be abused and is not preffered. If possible, let the user create an application in spotify dashboard or let a server handle the spotify communication. :::

private static EmbedIOAuthServer _server;

public static async Task Main()
{
  // Make sure "http://localhost:5000/callback" is in your spotify application as redirect uri!
  _server = new EmbedIOAuthServer(new Uri("http://localhost:5000/callback"), 5000);
  await _server.Start();

  _server.AuthorizationCodeReceived += OnAuthorizationCodeReceived;

  var request = new LoginRequest(_server.BaseUri, "ClientId", LoginRequest.ResponseType.Code)
  {
    Scope = new List<string> { Scopes.UserReadEmail }
  };
  BrowserUtil.Open(uri);
}

private static async Task OnAuthorizationCodeReceived(object sender, AuthorizationCodeResponse response)
{
  await _server.Stop();

  var config = SpotifyClientConfig.CreateDefault();
  var tokenResponse = await new OAuthClient(config).RequestToken(
    new AuthorizationCodeTokenRequest(
      "ClientId", "ClientSecret", response.Code, "http://localhost:5000/callback"
    )
  );

  var spotify = new SpotifyClient(tokenResponse.AccessToken);
  // do calls with spotify and save token?
}

For real examples, have a look at Example.CLI.PersistentConfig and Example.CLI.CustomHTML