How To: Use Recaptcha with Devise

To add Google's ReCaptcha to your site:

1. Install the ReCaptcha gem
2. Add <%= recaptcha_tags %> to your view.
3. Include a prepend_before_action for any action you want to secure:

class RegistrationsController < Devise::RegistrationsController
  prepend_before_action :check_captcha, only: [:create] # Change this to be any actions you want to protect.

  private
    def check_captcha
      unless verify_recaptcha
        self.resource = resource_class.new sign_up_params
        respond_with_navigational(resource) { render :new }
      end 
    end
end

4. If you are adding reCaptcha in registration page then add the below lines in config/routes.rb. The first one is configuration of devise generated controller (rails g devise:controller [scope]), but if you are using your own "registrations_controller.rb" then use it accordingly.

a) For Devise Generated Controller Route Settings (config/routes.rb):

devise_for :users, controllers: { ... , registrations: "user/registrations", ... }

b) For custom "registrations_controller.rb" in "app/controller" directory, use this Route Settings (config/routes.rb):

devise_for :users, controllers: { ... , registrations: "registrations", ... }

show recaptcha error, add below line, where you want show flash, ex. registrations\new.html.erb

  <%= flash[:recaptcha_error] %> # <== add this one
  <%= recaptcha_tags %>

Some of the available options for #verify_recaptcha can be found here