Class: SdkOAuth2Flow

Version 1.1 - Updated on 8/11/2016



The standard OAuth 2.0 authorization helper. Use this if you’re writing a web app.

Defined Under Namespace


Constructor Details

#initialize(consumer_key, consumer_secret, redirect_uri, session, csrf_token_session_key, locale = nil) ⇒ SdkOAuth2Flow

  • consumer_key: Your application’s Key
  • consumer_secret: Your application’s Secret
  • redirect_uri: The URI to which the server will redirect the user after the user has authorized your app. This URI must be HTTPs-based and pre-registered with the servers, though localhost URIs are allowed without pre-registration and can be either HTTP or HTTPS.
  • session: A hash that represents the current web app session. It is used to save the CSRF token.
  • locale: The locale of the user currently using your app, such as en or en_US.
def initialize(consumer_key, consumer_secret, redirect_uri, session, csrf_token_session_key, locale=nil)
  super(consumer_key, consumer_secret, locale)
  if not redirect_uri.is_a?(String)
    raise ArgumentError, "redirect_uri must be a String, got #{consumer_secret.inspect}"
  @redirect_uri = redirect_uri
  @session = session
  @csrf_token_session_key = csrf_token_session_key

Instance Method Details


#finish(query_params) ⇒ Object

Call this method after the user has visited the authorize URL, granted your app access to his or her content and then has been redirected to your redirect URI.

  • query_params: The query params on the GET request to your redirect URI.

Returns a tuple of access_token, user_id and url_state:

  • access_token which can be used to construct an SdkClient.
  • user_id is the user ID of the user that jst approved your app.
  • url_state is the value you originally passed in to start().

Can throw the following:

  • BadRequestError
  • BadStateError
  • CsrfError
  • NotApprovedError
  • ProviderError
  • SdkError
def finish(query_params)
  csrf_token_from_session = @session[@csrf_token_session_key]

  # Check well-formedness of request.

  state = query_params['state']
  if state.nil?
    raise"Missing query parameter 'state'.")

  error = query_params['error']
  error_description = query_params['error_description']
  code = query_params['code']

  if not error.nil? and not code.nil?
    raise"Query parameters 'code' and 'error' are both set;" +
                              " only one must be set.")
  if error.nil? and code.nil?
    raise"Neither query parameter 'code' or 'error' is set.")

  # Check CSRF token

  if csrf_token_from_session.nil?
    raise"Missing CSRF token in session.");
  unless csrf_token_from_session.length > 20
    raise"CSRF token unexpectedly short: #{csrf_token_from_session.inspect}")

  split_pos = state.index('|')
  if split_pos.nil?
    given_csrf_token = state
    url_state = nil
    given_csrf_token, url_state = state.split('|', 2)
  if not Sdk::safe_string_equals(csrf_token_from_session, given_csrf_token)
    raise"Expected #{csrf_token_from_session.inspect}, " +
                        "got #{given_csrf_token.inspect}.")

  # Check for error identifier

  if not error.nil?
    if error == 'access_denied'
      # The user clicked "Deny"
      if error_description.nil?
        raise"No additional description from server.")
        raise"Additional description from server: #{error_description}")
      # All other errors.
      full_message = error
      if not error_description.nil?
        full_message += ": " + error_description

  # If everything went ok, make the network call to get an access token.

  access_token, user_id = _finish(code, @redirect_uri)
  return access_token, user_id, url_state


#start(url_state = nil) ⇒ Object

Starts the OAuth 2.0 authorizaton process, which involves redirecting the user to the returned “authorization URL”. When the user then either approves or denies your app access, the user will be redirected to the redirect_uri you provided to the constructor. Call finish() to complete the process.

This function saves a CSRF token to the session and csrf_token_session_key you provided to the constructor. This CSRF token is checked on finish() to prevent request forgery.

  • url_state: Any data you would like to keep in the URL through the authorization process. This exact value is returned to you when you call finish().

Returns the URL to redirect the user to.

def start(url_state=nil)
  unless url_state.nil? or url_state.is_a?(String)
    raise ArgumentError, "url_state must be a String"

  csrf_token = SecureRandom.base64(16)
  state = csrf_token
  unless url_state.nil?
    state += "|" + url_state
  @session[@csrf_token_session_key] = csrf_token

  return _get_authorize_url(@redirect_uri, state)

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