#235 Devise and OmniAuth (revised)

rails g migration add_omniauth_to_users provider uid
rake db:migrate

gem 'omniauth-twitter'

config.omniauth :twitter, ENV["TWITTER_CONSUMER_KEY"], ENV["TWITTER_CONSUMER_SECRET"]

devise :omniauthable, # ...

def self.from_omniauth(auth)
  where(auth.slice(:provider, :uid)).first_or_create do |user|
    user.provider = auth.provider
    user.uid = auth.uid
    user.username = auth.info.nickname
  end
end

def self.new_with_session(params, session)
  if session["devise.user_attributes"]
    new(session["devise.user_attributes"], without_protection: true) do |user|
      user.attributes = params
      user.valid?
    end
  else
    super
  end
end

def password_required?
  super && provider.blank?
end

def update_with_password(params, *options)
  if encrypted_password.blank?
    update_attributes(params, *options)
  else
    super
  end
end

<%= link_to "Sign in with Twitter", user_omniauth_authorize_path(:twitter) %>

devise_for :users, path_names: {sign_in: "login", sign_out: "logout"},
                   controllers: {omniauth_callbacks: "omniauth_callbacks"}

class OmniauthCallbacksController < Devise::OmniauthCallbacksController
  def all
    user = User.from_omniauth(request.env["omniauth.auth"])
    if user.persisted?
      flash.notice = "Signed in!"
      sign_in_and_redirect user
    else
      session["devise.user_attributes"] = user.attributes
      redirect_to new_user_registration_url
    end
  end
  alias_method :twitter, :all
end

<% if f.object.password_required? %>
  ...
<% end %>

<% if f.object.encrypted_password.present? %>
  ...
<% end %>