'Constructor
@param channel: Facebook channel (Row) with API credentials:
{app_id=clientID, app_secret=clientSecret}'

def __init__(self, channel):

    from facebook import GraphAPI, GraphAPIError
    self.GraphAPI = GraphAPI
    self.GraphAPIError = GraphAPIError
    request = current.request
    settings = current.deployment_settings
    scope = 'email,user_about_me,user_location,user_photos,user_relationships,user_birthday,user_website,create_event,user_events,publish_stream'
    redirect_uri = ('%s/%s/default/facebook/login' % (settings.get_base_public_url(), request.application))
    OAuthAccount.__init__(self, client_id=channel.app_id, client_secret=channel.app_secret, auth_url=self.AUTH_URL, token_url=self.TOKEN_URL, scope=scope, redirect_uri=redirect_uri)
    self.graph = None
