setup recaptcha-v3 with rails

place_with_recaptcha.html.erb

<%= from_for(@your_instance) do |f| %>
   <%= button_to 'submit', '', { class: 'btn', onclick: "reCaptcha('your_action')" } %>
   <%= f.submit 'hide this btn', class: 'hidden', id: 'submit_this_form' %>
<% end %>

<script src="https://www.google.com/recaptcha/api.js?render=<%= ENV['RECAPTCHA_SITE_KEY'] %>"></script>
<script>
  function reCaptcha(action) {
    event.preventDefault();
    grecaptcha.ready(function () {
      grecaptcha.execute('<%= ENV['RECAPTCHA_SITE_KEY'] %>', { action: action }).then(function (token) {
        $('input[name="g-recaptcha-token"]').remove();
        $('form').prepend('<input type="hidden" name="g-recaptcha-token" value="' + token + '">');
        $('#submit_this_form').click();
      });
    });
  }
</script>

validatable.rb

module Validatable
  # thanks https://github.com/igorkasyanchuk/new_google_recaptcha
  # token = params['g-recaptcha-token']
  def recaptcha_validated?(token)
    uri    = URI("https://www.google.com/recaptcha/api/siteverify?secret=#{ ENV['RECAPTCHA_SECRET_KEY'] }&response=#{token}")
    result = JSON.parse(Net::HTTP.get(uri))
    !!result["success"]
  end
end

You can extract url to constant, just looks nicer, something like this:

GOOGLE_RECAPTCHA_URL = "https://www.google.com/recaptcha/api/siteverify"
...
URI.join(GOOGLE_RECAPTCHA_URL, "?secret=#{ ENV['RECAPTCHA_SECRET_KEY'] }&response=#{token}")