How to nest devise_invitable such that a user can be invited to only 1 hotel

Goal

I would like to let a user.admin invite a user to only one of its hotels with the devise_invite gem.

=> User and Hotel are connected via a Join table UserHotel.

Issue

I started to doubt the way I set up devise(_invitable). With the way I currently set it up, I am not able to create the user_hotel Join_table and/or add the specific hotel params to the invited user, see output below for checks:

• controller >> @user.hotels => #<ActiveRecord::Associations::CollectionProxy []>

• console:

pry(main)> User.invitation_not_accepted.last.hotels
  User Load (0.6ms)  SELECT  "users".* FROM "users" WHERE "users"."invitation_token" IS NOT NULL AND "users"."invitation_accepted_at" IS NULL ORDER BY "users"."id" DESC LIMIT $1  [["LIMIT", 1]]
  Hotel Load (0.4ms)  SELECT "hotels".* FROM "hotels" INNER JOIN "user_hotels" ON "hotels"."id" = "user_hotels"."hotel_id" WHERE "user_hotels"."user_id" = $1  [["user_id", 49]]
=> []

UPDATE

The issue seems to be in the many-to-many relationship between user and hotel. When I break my controller 'new' action after hotel.user.new and test it I het the following:

• >> @user.hotels => #<ActiveRecord::Associations::CollectionProxy []>
• >> @hotel.users => #<ActiveRecord::Associations::CollectionProxy [#<User id: 2, email: "test@hotmail.com", created_at: "2019-11-05 14:17:46", updated_at: "2019-11-05 15:04:22", role: "admin">, #<User id: nil, email: "", created_at: nil, updated_at: nil, role: "admin">]>

Note I set up users with devise, such that my users controller is build up as:

• users/confirmations_controller.rb
• users/invitations_controller.rb
• users/omniauth_callbacks_controller.rb
• users/password_controller.rb
• users/registrations_controller.rb
• users/sessions_controller.rb
• users/unlocks_controller.rb

Code

routes

Rails.application.routes.draw do

  devise_for :users

  resources :hotels do
devise_for :users, :controllers => { :invitations => 'users/invitations' }
  end
end

models

class User < ApplicationRecord
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable, :trackable and :omniauthable
  has_many :user_hotels, dependent: :destroy
  has_many :hotels, through: :user_hotels
  accepts_nested_attributes_for :user_hotels
  enum role: [:owner, :admin, :employee]
  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

class UserHotel < ApplicationRecord
  belongs_to :hotel
  belongs_to :user
end

class Hotel < ApplicationRecord
  has_many :user_hotels, dependent: :destroy
  has_many :users, through: :user_hotels
  accepts_nested_attributes_for :users, allow_destroy: true, reject_if: ->(attrs) { attrs['email'].blank? || attrs['role'].blank?}
end

views/hotels/show

<%= link_to "invite new user", new_user_hotel_invitation_path(@hotel)%>

controllers/users/invitations_controller.rb

class Users::InvitationsController < Devise::InvitationsController
  def new
    @hotel = Hotel.find(params[:hotel_id])
    @user = @hotel.users.new
  end

  def create
    @hotel = Hotel.find(params[:hotel_id])
    @user = @hotel.users.new(hotel_user_params)
    @user.invite!
  end

  private
  def hotel_user_params
    params.require(:user).permit(:email, :role,
      hotel_users_attributes: [:hotel_id])
  end
end

views/invitations/new.html.erb

<h2><%= t "devise.invitations.new.header" %></h2>

<%= simple_form_for(resource, as: resource_name, url: user_hotel_invitation_path(@hotel), html: { method: :post }) do |f| %>  <%= f.error_notification %>

  <% resource.class.invite_key_fields.each do |field| -%>
    <div class="form-inputs">
      <%= f.input field %>
    </div>
  <% end -%>

      <%= f.input :role, collection: [:owner, :admin, :employee] %>
  <div class="form-actions">
    <%= f.button :submit, t("devise.invitations.new.submit_button") %>
  </div>
<% end %>

I have something working, even tough I am not sure if this is the best way to do it (read: I highly doubt it).

class Users::InvitationsController < Devise::InvitationsController
  def new
    @hotel = Hotel.find(params[:hotel_id])
    @user = @hotel.users.new
    @user.hotels << @hotel
  end

  def create
    @hotel = Hotel.find(params[:hotel_id])
    @user = @hotel.users.new(hotel_user_params)
    @user.hotels << @hotel
    @user.invite!
  end