Ruby POST call from server fails - ruby

Question

I'm trying to make a spotify web manager with ruby, to make that I'm following the Authorization Guide.
My backend looks similar to the example made by the spotify's guys in this github. You can see mine here code here.
So the error I'm getting are 400 - Bad request or 415 - Unsupported media type.
At first I was using the net/http core library, but because maybe I was doing something wrong I've used Typhoeus and the result are the same.
This is the code is not working:
request = Typhoeus::Request.new("https://accounts.spotify.com/api/token",
method: :post,
body: {
grant_type: "authorization_code",
code: code,
redirect_uri: "http://localhost:5000/auth/spotify/callback"
},
headers: {
"Authorization": "Basic #{Base64.strict_encode64("#{settings.spotify_id}:#{settings.spotify_key}")}"
},
followlocation: true
)
logger.info request.inspect
request.on_complete do |response|
logger.info "[]" * 100
logger.info response
if response.success?
logger.info "SUCCESS"
elsif response.timed_out?
logger.info "TIMED OUT"
elsif response.code == 0
logger.info response.return_message
else
logger.info "HTTP request failed: #{response.code.to_s}"
redirect '/auth/failure'
end
end
request.run
Well, if someone of you have any idea of what is happenning, It would be helpful to know it.
Thanks in advance.
Edit
The string interpolation is is working properly, has been tested on console.
"Basic #{Base64.strict_encode64("#{settings.spotify_id}:#{settings.spotify_key}")}"
About the redirect_uri, must to work well, one thing because the guide is explained with localhost example, and second, the first request explained on the Authorization Guide is working properly, the problem happens when I'm trying to do the 4 step on that guide.

Answer 1

Are you sure that kind of string interpolation works? Did you look at the traffic in wireshark to see if it is working correctly? It looks suspicious cause you use double-quotes within double quotes and still expect it to work. If you don't wanna set up wireshark, have your app post the request text on the console. Furthermore, are you sure Spotify will allow redirect_uri's with localhost? Also, when do you get the 400, and when do you get the 415? This is important information, you can't just conflate them like that.

Answer 2

I've changed the Typhoeus gem for HTTParty, and now the error is becoming clearer.
The main thing here is not the 400 or the 415 error, is the message attached to this error. The error here is:
"error"=>"invalid_grant", "error_description"=>"Invalid authorization code"
So, It's my fault not to be aware of that, but was not clear the message, sometimes the fatigue and frustration makes you not seeing the obvious.
Now, just have to know why the auth. code is not valid.
Anyway thanks for the help.