未定义的方法nil：NilClass ruby

Question

What I need to do is create a page where the user will type in a last name and the system will return information related to it. I keep receiving the error "undefined method `each' for nil:NilClass." I am stuck and can not debug it any help or guidance would be greatly appreciated.

CODE FOR THE INPUT PAGE

<%= form_tag(showcustcourses_custcoursesout_path, :controller => "showcustcourses", :action => "custcoursesout", :method => "post") do %>
  <div class="field">
    <%= label_tag :Customer_Name %><br />
    <%= text_field_tag :customer_name_in %>
  </div>

  <div class="actions">
    <%= submit_tag "Submit Customer Name" %>
  </div>
<% end %>

CODE FOR THE CONTROLLER

class BookinController < ApplicationController

  def bookin
  end

  def bookout
    @customer_name = params[:customer_name_in]
    @r = Customer.find_by_last(@customer_name)
    @rate_list = @r ? @r.rates : nil
  end
end

CODE FOR THE OUTPUT PAGE ( <% @customer_list.each do |m| %> is throwing the error)

<h1>Bookin#bookout</h1>
<p>Find me in app/views/bookin/bookout.html.erb</p>

<center><table width = 65% border = 1> 
  <tr> <th> Customer Name</th><th> Room Number </th>  <th> Cost </th></tr>   
  <% @customer_list.each do |m| %>
    <tr> <td> <%= m.name %> </td> <td> <%= m.roomnumber %> </td> <td> <%= m.cost %> </td> </tr> 
  <% end %>
</table> </center><br /> <br />

Answer 1

You are getting the error undefined method 'each' for nil:NilClass because you forgot to set the value of instance variable @customer_list . So, @customer_list is nil .

You need to set @customer_list variable in the action corresponding to your view which in your case is bookout action as you are rendering bookout.html.erb .

Simply, do this in BookinController#bookout :

  def bookout
    ## ...
    @customer_list = Customer.all ## Add this
  end

UPDATE

As per the chat discussion, OP needed to show last(from customers table), roomlevel(from apples table), cost(from rates table)

Suggested to modify

bookout method as below:

def bookout 
  @customer_list = Customer.all 
  @customer_name = params[:customer_name_in] 
end

and bookout.html.erb as below:

<% @customer_list.each do |customer| %> 
  <% customer.bookings.each do |booking| %> 
  <tr> 
    <td> <%= customer.last %> </td> 
    <td> <%= booking.apple.room_level %> </td> 
    <td> <%= booking.apple.cost %> </td> 
  </tr> 
  <% end %> 
<% end %>

Also, OP's schema was not correct to achieve this result. Added apple_id to bookings table and removed rate_id from it.

NOTE: As you don't want bookings to be associated with rates table, rate_id was removed from bookings table. You would have to add cost field in apples table to display the cost in the view.

Answer 2

Add this in your controller. It will bring details of all customers.

def bookin
   @customer_list = Customer.all 
end

def bookout
  @customer_list = Customer.all 
  @customer_name = params[:customer_name_in]
  @r = Customer.find_by_last(@customer_name)
  @rate_list = @r ? @r.rates : nil
end

If still it returns nil error, then it means you do not have any customer records in database.

<h1>Bookin#bookout</h1>
<p>Find me in app/views/bookin/bookout.html.erb</p>

 <center><table width = 65% border = 1> 
 <tr> <th> Customer Name</th><th> Room Number </th>  <th> Cost </th></tr>   
  #check if object is not nil
 <% if !@customer_list.nil? %>
   <% @customer_list.each do |m| %>
    <tr> 
      <td> <%= m.name %> </td> 
      <td> <%= m.roomnumber %> </td> 
      <td> <%= m.cost %>      
     </td> 
    </tr> 
    <% end %>

  <% else %>
   <p> no customers available </p>
  <% end %>

  </table>
  </center>

Answer 3

@customer_list is not defined

defined it in controller like this

@customer_list = Customer.all