Cannot access model method inside its controller in Rails

Question

In my Rails app, I have a controller tickets_controller.rb and model ticket.rb. For creating a ticket I have the following form,

<%= form_for(@ticket) do |f| %>
  <% if @ticket.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@ticket.errors.count, "error") %> prohibited this ticket from being saved:</h2>

      <ul>
      <% @ticket.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

    <%= f.label :ref_no, "Reference Number"%><br/>
    <%= f.text_field :ref_no%><br />

    <%= f.label :category, "Type of Request"%><br/>
    <%= f.text_field :category_id %><br />

    <%= f.label :issue, "Issue"%><br/>
    <%= f.text_area :issue%><br />

    <%= f.label :ticket_priority, "Priority level"%><br/>
    <%= f.text_field :ticket_priority_id %><br />

    <%= f.label :ticket_status, "Current Status"%><br/>
    <%= f.text_field :ticket_status_id %><br />

    <%= f.label :project, "Project"%><br/>
    <%= f.text_field :project_id %><br />

  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

I want to create a unique random reference number on the form_load (ticket/new), and it should be appended to Reference Number text field. While creating a new reference number, it should check the tickets table for duplication. So I have the following model,

ticket.rb

class Ticket < ActiveRecord::Base

  attr_accessible :issue, :ticket_status_id, :ticket_priority_id, :ref_no, :category_id, :project_id
  has_many :ticket_statuses , :through => :ticket_histories
  has_one :ticket_priority
  belongs_to :user

  before_create :generate_token

  protected


  def generate_num
    self.token = loop do
      random_token = random(1000000000)
      break random_token unless Ticket.exists?(:ref_no => random_token)
    end
  end

end

and

tickets_controller.rb

class TicketsController < ApplicationController
   before_filter :authenticate_user!
  #load_and_authorize_resource

  def index
    @tickets = Ticket.all

    respond_to do |format|
      format.html # index.html.erb
      format.json { render :json => @tickets }
    end
  end


  def show
    @ticket = Ticket.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render :json => @ticket }
    end
  end


  def new
    @ticket = Ticket.new

    @ref_no = Ticket.generate_num

    @categories = Category.all
    @status = TicketStatus.first
    @priorities = TicketPriority.all
    respond_to do |format|
      format.html # new.html.erb
      format.json { render :json => @ticket }
    end
  end


  def edit
    @ticket = Ticket.find(params[:id])
  end


  def create
    @ticket = Ticket.new(params[:ticket])
    respond_to do |format|
      if @ticket.save
        format.html { redirect_to @ticket, :notice => 'Ticket was successfully created.' }
        format.json { render :json => @ticket, :status => :created, :location => @ticket }
      else
        format.html { render :action => "new" }
        format.json { render :json => @ticket.errors, :status => :unprocessable_entity }
      end
    end
  end

  def update
    @ticket = Ticket.find(params[:id])

    respond_to do |format|
      if @ticket.update_attributes(params[:ticket])
        format.html { redirect_to @ticket, :notice => 'Ticket was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render :action => "edit" }
        format.json { render :json => @ticket.errors, :status => :unprocessable_entity }
      end
    end
  end


  def destroy
    @ticket = Ticket.find(params[:id])
    @ticket.destroy

    respond_to do |format|
      format.html { redirect_to tickets_url }
      format.json { head :no_content }
    end
  end
end

When I run my app, I am getting the following error. Can anyone help?

 NoMethodError in TicketsController#new

undefined method `generate_num' for #<Class:0x7f5cdc1f21c0>

Rails.root: /home/local/Rajesh/ticket_system
Application Trace | Framework Trace | Full Trace

app/controllers/tickets_controller.rb:27:in `new'

Answer 1

Change your model method generate_num to self.generate_num.

def self.generate_num
    token = loop do
      random_token = random(1000000000)
      break random_token unless Ticket.exists?(:ref_no => random_token)
    end
end

Answer 2

You have defined and instance method and you are calling it using Class

Call method using object

@ticket.generate_num