问RoR: InviteMailer：`new_user_invite的未定义方法类

EN

class InvitesController < ApplicationController

  def new
    @invite = Invite.new
  end

  def create
    @invite = Invite.new(invite_params) # Make a new Invite
    @invite.sender_id = current_user.id # set the sender to the current user
    if @invite.save
       InviteMailer.new_user_invite(@invite, new_user_registration_path(:invite_token => @invite.token)).deliver #send the invite data to our mailer to deliver the email
       flash[:notice] = "Thanks, invitation has successfully been sent"
       redirect_to user_groups_url
    else
       flash[:notice] =  "oh no, creating an new invitation failed"
       redirect_to invites_path
    end
  end

  private

    def invite_params
      params.require(:invite).permit(:email, :recipient_id, :user_group_id, :sender_id)
    end

end

class Invite < ApplicationRecord

  before_create :generate_token

  def generate_token
   self.token = Digest::SHA1.hexdigest([self.user_group_id, Time.now, rand].join)
  end


end

Rails.application.routes.draw do
  resources :memberships
  resources :user_groups
  # mount RailsAdmin::Engine => '/admin', as: 'rails_admin'
  # devise_for :users
  # delete '/logout', to: 'sessions#destroy'
  default_url_options :host => "smtp.gmail.com"

  devise_for :users, controllers: {
      sessions: 'users/sessions',
      passwords: 'users/passwords',
      registrations: 'users/registrations'
  }
  get 'static_pages/index'

  resources :invites

  namespace :admin, path: '/admin' do
    resources :users, except: [:show] do
      member do
        post :resend_invite
        post :enable
      end
    end
    resources :roles, only: [:index, :edit, :update, :new, :create]
    get "audits/index"
  end
end

= simple_form_for @invite , :url => invites_path do |f|
  = f.error_notification
  = f.error_notification message: f.object.errors[:base].to_sentence if f.object.errors[:base].present?

  space-left3.space-below3
    = f.hidden_field :user_group_id, :value => @invite.user_group_id
    = f.input :email, placeholder: 'user@domain.com'
  .form-actions
    button.btn.btn-primary type="submit" Send

class InviteMailer < ApplicationMailer
  def self.new_user_invite(invite, signup_url)
    subject    'Invite'
    recipients invite.recipient_email
    from       'example@gmail.com'
    body       :invite => invite, :signup_url => signup_url
    invite.update_attribute(:sent_at, Time.now)
  end

  def invite
    @greeting = "Hi"

    mail to: "to@example.org"
  end
end

 class ApplicationMailer < ActionMailer::Base
      default from: 'from@example.com'
      layout 'mailer'
    end