Return to the previous or a specific page after login with OmniAuth

It's a common practice to return the user to the previous page or a specific page after he/she successfully logged in. If you're using OmniAuth, it's already well supported in the gem! The is request.env['omniauth.origin'].

Scenario: return to the previous page

Using the same code example from omniauth gem:

sessions_controller.rb
class SessionsController < ApplicationController
  def create
    user = User.find_or_create_from_auth_hash(auth_hash)
    Current.user = user
    redirect_to '/' # we want to redirect to previous page here
  end

  private

  def auth_hash
    request.env['omniauth.auth']
  end
end

The previous page, or to be specific, the request referrer is stored in request.env['omniauth.origin'], so you could write like this:

def create
  # ...
  redirect_to origin
end

private

def origin
  request.env['omniauth.origin']
end

Since by default it's the same as the request referrer, the code isn't that much different than the Rails redirect_back. So if your app is simple enough, the code below would also work:

redirect_back fallback_location: root_path

Then what's the advantage of using request.env['omniauth.origin']? Let's see the next scenario.

Scenario: return to a specific page

When would you want to redirect the user to a specific page rather than previous one?

I can think of some scenarios like the typical "Find followings on Twitter" flow in which you'd usually see a list of people you're following after connecting with Twitter, or "Connect to Github" flow in which you'd choose to import some repos.

link_to 'Find followings on Twitter', "/auth/twitter?origin=#{twitter_followings_path}"
link_to 'Connect to Github', "/auth/github?origin=#{github_repos_path}" 

And you can reuse the same controller code above to handle it:

redirect_to request.env['omniauth.origin']

Customize the origin param

You can also customize the origin param name in the link if you want.

config/initializers/omniauth.rb
provider :twitter, ENV['KEY'], ENV['SECRET'], origin_param: 'return_to'

Then, your link would be "/auth/twitter?return_to=...", but in the controller, you'd still need to use the same key to access that link: request.env['omniauth.origin'].

Note that you can access any params you pass in the auth link via request.env['omniauth.params']. The origin is just a more convenient and more specific way to handle where to return the user to.

Recap

• Given /auth/twitter
  • request.env['omniauth.origin'] = request referrer
• Given /auth/twitter?origin=URL
  • request.env['omniauth.origin'] = URL
• Given /auth/twitter?origin=URL&foo=bar
  • request.env['omniauth.params'] = { "origin" => URL, "foo" => "bar" }
• Customize origin_param: 'return_to'
  • so to use /auth/twitter?return_to=URL