How can I access authorization keys required for OAuth 2.0 authorization with Spotify?

I am currently trying to access the Spotify API calls using MATLAB's webwrite / web commands, however I have been unsuccessful with retrieving the authorization code that is generated in the opened url.

client_id = "PLACEHOLDER_ID"; % Specific Application client id
redirect_uri = 'PLACEHOLDER_LINK';
scope = 'user-read-private user-read-email';
response_type = 'code';
    
auth_url = "https://accounts.spotify.com/authorize?";
auth_url = strcat(auth_url, "client_id="+client_id);
auth_url = strcat(auth_url, "&redirect_uri="+redirect_uri);
auth_url = strcat(auth_url, "&response_type="+response_type);

data = web(auth_url);

At the moment, this code will open up a new brower with the spotify sign-in and authorization button, however I have no way of being able to retrieve the url generated after pressing the authorize button. Does anyone know of a way to do this, or a better way to complete authorization within matlab api interations?

Answer 1

[Chetan]

Hi @Hank Helmers,

I understand you are trying to implement OAuth authentication in MATLAB to interact with the Spotify API. You have successfully created the authorisation URL and opened it in a web browser using the web function.

However, you're facing an issue with retrieving the callback URL, which contains the authorization code after the user presses the authorize button.

Here's a step-by-step guide on how to proceed:

1. Setting Up a Local Web Server: Since MATLAB does not inherently support OAuth redirections, you will need to set up a local web server within MATLAB that will handle the callback from Spotify's OAuth service.
2. Listening for the Callback: After the user authorizes your application on Spotify, the service will redirect to specified "redirect_uri", including the authorization code as a query parameter.
3. Example Implementation: Below is a basic example of how to create a simple HTTP server in MATLAB that listens for the OAuth callback:

% Set up the parameters for the Spotify API authorization request
client_id = 'YOUR_CLIENT_ID';
redirect_uri = 'http://localhost:8080';
scope = 'user-read-private user-read-email';
response_type = 'code';
% Construct the authorization URL
auth_url = "https://accounts.spotify.com/authorize?";
auth_url = strcat(auth_url, "client_id=", client_id);
auth_url = strcat(auth_url, "&redirect_uri=", urlencode(redirect_uri));
auth_url = strcat(auth_url, "&scope=", urlencode(scope));
auth_url = strcat(auth_url, "&response_type=", response_type);
% Open the authorization URL in the default web browser
web(auth_url, '-browser');
% Start a local web server to listen for the redirect
tcpipServer = tcpserver('localhost', 8080);
% Wait for a connection
while ~tcpipServer.Connected
    pause(1);
end
% Read the data from the connection (includes the authorization code)
data = read(tcpipServer, tcpipServer.BytesAvailable, 'string');
% Extract the authorization code from the data
code = extractBetween(data, 'code=', ' ');
% Close the server
clear tcpipServer;
% Display the authorization code
disp(code);

Refer to following MathWorks Documentation regarding the TCP server and web:

• https://www.mathworks.com/help/slrealtime/io_ref/tcpserver.html
• https://www.mathworks.com/help/matlab/ref/web.html

You may use your client_id and change the variables required according to the use case.

Hope it helps !