This is a documentation stub and should be expanded. Feel free to help make it more robust!
The setup phase exists to allow for request-time modification of an OmniAuth strategy. Here's how you might use it for Twitter auth on a Rack app:
SETUP_PROC = lambda do |env| request = Rack::Request.new(env) user = User.find_by_subdomain(request.subdomain) env['omniauth.strategy'].options[:consumer_key] = user.consumer_key env['omniauth.strategy'].options[:consumer_secret] = user.consumer_secret end use OmniAuth::Builder.new do provider :twitter, :setup => SETUP_PROC end
As you can see, you can pass a Proc (or anything that responds to
call) to the
:setup option when you specify a strategy and it will be called before the request and callback phases. Here you will have access to the running strategy via
env['omniauth.strategy'] and you can modify it how you like.
Here's another example of using Facebook auth on a Rails app that uses a helper to return an ActiveRecord object with attributes of the current domain:
include ApplicationHelper SETUP_PROC = lambda do |env| req = Rack::Request.new(env) # Note client_id & client_secret for Facebook env['omniauth.strategy'].options[:client_id] = current_domain(req).fb_app_id env['omniauth.strategy'].options[:client_secret] = current_domain(req).fb_app_secret end # Note the below block is different for a Rails app Rails.application.config.middleware.use OmniAuth::Builder do provider :facebook, setup: SETUP_PROC end
You can use setup phase without block – it will work too if setup option is found. In Rails app you pass setup option like this:
Rails.application.config.middleware.use OmniAuth::Builder do provider :facebook, Config['appKey'], Config['appSecret'], :setup => true end
and omniauth will look for route like '/auth/:provider/setup' which you can match to SessionsController for example:
match '/auth/:provider/setup' => 'sessions#setup'
In SessionsController#setup you can manage request options like this:
class SessionsController < ApplicationController def setup # in this example facebook keys for different site domains are stored in Config request.env['omniauth.strategy'].options[:client_id] = Config[domain]['appKey'] request.env['omniauth.strategy'].options[:client_secret] = Config[domain]['appSecret'] render :text => "Omniauth setup phase.", :status => 404 end end
CAVEAT: When calling through to your app in the setup phase (with
:setup => true as above), omniauth will use a shallow copy of
request.env as opposed to the real
request.env, which could cause problems if you do custom manipulations to the env or expect custom keys/values that you set in the setup phase to be accessible in the request phase. For Rails, also note that your controller callbacks (
before_filters etc.) will be run, which is probably not what you want (you can run them in the request phase instead).