Trying to make authorization post call with HTTP post

Hello, I am trying to access a spotify access token using matlab's api requests, and at the moment I just get a 'Bad Request' output and I was wondering if anyone had any ideas?

I have to have the content type of the urlencoded, and a header with Authorization and my id and secret id encoded.

client_id = "ID";
secret_id = "SECRET";
encodedId = base64encode(strcat(client_id, ":", secret_id));

disp(encodedId);

headerField = HeaderField('Content-Type', 'application/x-www-form-urlencoded', "Authorization", strcat("Basic ", encodedId));

inputParameters = struct('grant_type', "authorization_code", "code", auth_code, "redirect_uri", redirect_uri);
aTest = jsonencode(inputParameters);

options = HTTPOptions();
method = RequestMethod.POST;

request = RequestMessage(method,headerField, aTest)
show(request)

resp = send(request,token_url, options);
disp(resp)

Answer 1

[Suraj]

Hi Hank,

I understand that you're trying to send a POST request to a Spotify API. For this you'll have to send "grant_type", "code" and "redirect_uri" as query parameters because the request content type is "application/x-www-form-urlencoded".

In the code snippet you've attached however, this payload is being sent as JSON-encoded string. Please refer to the code snippet below to learn how you can compose this HTTP request correctly.

client_id = "ID";
secret_id = "SECRET";
encodedId = base64encode(strcat(client_id, ":", secret_id));

disp(encodedId);

headerField = HeaderField('Content-Type', 'application/x-www-form-urlencoded', "Authorization", strcat("Basic ", encodedId));

% Use the "FormProvider" class to create a URI query string
inputParameters = matlab.net.http.io.FormProvider('grant_type', "authorization_code", "code", auth_code, "redirect_uri", redirect_uri);

options = HTTPOptions();
method = RequestMethod.POST;

request = RequestMessage(method,headerField, inputParameters)
show(request)

resp = send(request,token_url, options);
disp(resp)

In the above code snippet, "FormProvider" creates data suitable for a request message whose Content-Type is "application/x-www-form-urlencoded". You can also achieve this using "QueryParameter" class.

Please refer to the documentation for more details:

1. "FormProvider" class: https://www.mathworks.com/help/matlab/ref/matlab.net.http.io.formprovider-class.html
2. "QueryParameter" class: https://www.mathworks.com/help/matlab/ref/matlab.net.queryparameter-class.html

I hope this resolves your query.

Thanks & regards,

Suraj.