Using devise_invitable with enum User roles - ruby-on-rails

Question

1. Description core problem
I am implementing the devices_invitable gem for inviting users. The gem is correctly added, as I am able to send users the standard devices_invitable email to invite them for the application.
The problem that I am encountering, is that I am not sure how to enable an admin (to be identified with enum) to assign the role of the user they are inviting (e.g. they should enter an email AND role of the user they invite, which should then be correctly added to my DB).
Note: As you can see below, I'm currently trying to solve it using nested forms with the cocoon gem, but I am open to other approaches.
2. My current application
The application has 2 tables with a many to-many relationship between them:
(i) Users, with role attributes defined by enum.
(ii) Parks
The idea is to let an admin invite a new user to a park (not entire application) by entering email+role.
3. The code
user.rb
class User < ApplicationRecord
has_many :user_parks, dependent: :destroy
has_many :parks, :through => :user_parks
enum role: [:owner, :admin, :employee, :accountant]
after_initialize :set_default_role, :if => :new_record?
def set_default_role
self.role ||= :admin
end
devise :invitable, :database_authenticatable, :registerable,
:recoverable, :rememberable, :validatable, :invitable
end
park.rb
class Park < ApplicationRecord
has_many :user_parks, dependent: :destroy
has_many :users, :through => :user_parks
accepts_nested_attributes_for :users, allow_destroy: true, reject_if: ->(attrs) { attrs['email'].blank? || attrs['role'].blank?}
end
parks_controller.rb
class ParksController < ApplicationController
def update
#park = Park.find(params[:id])
authorize #park
url = Rails.application.routes.recognize_path(request.referrer)
last_action = url[:action]
if last_action == 'edit_users' & #park.user.last.nil?
#user=#park.user.last.invite!(email: park_params[:user][:email])
end
#park = #park.update_attributes(park_params)
redirect_to parks_path
end
def edit_users
#park = Park.find(params[:id])
authorize #park
end
private
def park_params
params.require(:park).permit(:name, users_attributes: [:email, :role, :_destroy])
end
end
edit_users.html.erb
<%= render 'users_edit_form', park: #park%>
_users_edit_form
<%= simple_form_for [#park] do |f|%>
<h1>Park</h1>
<% #park.users.each do |user| %>
<%= user.email %>
<% end %>
<div>
<% f.simple_fields_for User.new, :url=> new_user_invitation_path, html: { class: 'form-inline' } do |user| %>
<%= user.input :email %>
<%= user.input :role, priority: [:employee], collection:[:owner, :admin, :employee, :accountant] %>
<%= f.button :submit, 'Invite User', class: 'btn-primary' %>
<% end %>
</div>
#TEST for standard view (sends invite but does not assign park/role)
<%# link_to "new user add", new_user_invitation_path %>
<%= f.button :submit, 'Invite User', class: 'btn-primary' %>
<% end %>

Answer 1

1st issue I can see is you are using a bitwise & on this line:
if last_action == 'edit_users' & #park.user.last.nil?
you would usually use a logical and && or and
2nd issue with that line is #park.user should be #park.users if it's declared as a has_many
3rd issue is I'm not sure you need to be looking at request.referrer?
Assuming you can get to the invite! line then you might want to check the docs for the 2 different versions of invite!
When the user is already created:
user = User.find(42)
user.invite!(current_user) # current user is optional to set the invited_by attribute
see example in README
OR
When the user isn't created yet:
User.invite!(email: 'new_user#example.com', name: 'John Doe')
# => an invitation email will be sent to new_user#example.com
see example in README