Authorization code flow: get access token error invalid client_id

[pablior]

Hey guys ! 

I'm building a webapp based on Spotify API using RoR. To get the access token, I use the Autorization Code Flow process.

At step 2, I when make the [POST] to https://accounts.spotify.com/api/token, sending my client_id and client_secret base64 encoded, I have a 400 "Invalid client_id".
Then I tried to sending it in the headers and this time I have a 400 "Invalid authorization_code".

I'm a bit lost right now, your help is greatly appreciated 🙂

  def get_token
    api_endpoint = 'https://accounts.spotify.com/api/token'
    encoded_auth = Base64.encode64(ENV['SPOTIFY_CLIENT'] + ENV['SPOTIFY_SECRET']).delete("\n")

    body = {
      grant_type: 'authorization_code',
      code: params['code'],
      redirect_uri: "http://localhost:3000/auth/spotify/callback",
      client_id: ENV['SPOTIFY_CLIENT'],
      client_secret: ENV['SPOTIFY_SECRET']
    }
    headers = { Authorization: "Authorization: Basic #{encoded_auth}" }

    resp = HTTParty.post(
      api_endpoint,
      headers: headers,
      body: body
    )
  end

[kingosticks4]

Shouldn't you have separated the client ID and client secret with a colon character? And why is it prefixed with a hash character?