sign_in via facebook_api

Hi, everyone! I’m new in Elixir. I’m working on sign_in user on application via facebook login. I follow all the basic steps and get client_id, client_secret, redirect_uri and code. By using these parameters go to following link{app-id}&redirect_uri={redirect-uri}&client_secret={app-secre}&code={code-parameter}. when i link on this link, it’ll give me access_token in json response but when using Http client like (Tesla, HTTPoison) they show error: invalid_uri.

-> token_fb_url = """{client_id}&redirect_uri=#{redirect_uri}&client_secret=#{client_secret}&code=#{code}&format=json
-> Tesla.get(token_fb_url)

Please help me if possible by anyone.
Thanks in advance

Did you use this:

You don’t need to worry about anything at the lower level.