undefined method nil:NilClass ruby - ruby-on-rails

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_idwas 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