Invoices App

invoice.rb

class Invoice < ActiveRecord::Base
  attr_accessible :invoice_date, :company_id, :purchase_order, :vat_rate, :date_sent, :paid, :date_paid; 
  validate :invoice_date, :company_id, :vat_rate, :date_sent, :presence => true
  validate :status, :inclusion => { :in => ['draft', 'sent', 'paid'] }
  
  belongs_to :company
  has_many :invoice_items, :dependent => :destroy
  accepts_nested_attributes_for :invoice_items, :allow_destroy => true
  
  scope :outstanding, where(:paid => "false")
  scope :overdue, lambda { where('date_sent < ?', Date.today - 30.days)}
  scope :recently_paid, lambda { where('date_paid < ?', Date.today - 14.days)}
end

invoice_items.rb

class Invoice::InvoiceItems < ActiveRecord::Base
  attr_accessible :quantity, :unit_type, :unit_price, :details, :vat_rate

  belongs_to :invoice  

  scope :all, order('due_date ASC')
  
  validate :description, :quantity, :unit_cost, :presence => true
  validate :unit_price, :numericality => { :greater_than_or_equal_to => 0 }
  validate :quantity, :numericality => { :greater_than => 0 }
 # validate :discount, :numericality => { :greater_than_or_equal_to => 0, :less_than_or_equal_to => 100}
  validate :invoice_id, :presence => true, :unless => :nested
  attr_accessor :nested

end

invoice_items_controller.rb

class Invoices::InvoiceItemsController < ApplicationController
def show
    @item = InvoiceItem.find(params[:id])

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

invoices_controller.rb

class InvoicesController < ApplicationController
def show
    @invoice = Invoice.find(params[:id])
    @items = @invoice.invoice_items.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.pdf { render :layout => false }
      format.json { render json: @invoice }
    end
  end
end

routes.rb

Internalapp::Application.routes.draw do

  resources :invoices do
    resource :invoice_items
  end
  resources :notes
  resources :contracts
  resources :tasks
  resources :people
  resource :user, :as => 'account'  
  resources :adhoc_supports
  resources :users
  resources :roles
#  resources :admin
  resources :companies
  resources :mac_quotes
  resources :mac_values
  resources :ios_quotes
  resources :ios_values
  resources :users, :user_sessions
  resources :password_resets
  
  get "user_sessions/new"
  root :to => "home#index"
  
  get "home/index"
  match '/', :to => 'home#index'
  match 'signup' => 'users#new',              :as => :signup
  match 'login' => 'user_sessions#new',       :as => :login
  match 'logout' => 'user_sessions#destroy',  :as => :logout
  match 'activate(/:activation_code)' => 'users#activate', :as => :activate_account
  match 'send_activation(/:user_id)' => 'users#send_activation', :as => :send_activation
  match '/admin', :to => 'admin#index'
  match '/dashboard', :to => 'home#dashboard'
  match '/adhocsupport', :to => 'adhoc_supports#index'
  match '/people', :to => 'people#index'
  match '/companies', :to => 'companies#index'
  match '/quotes', :to => 'home#quotes'
  match '/help', :to =>'home#help'
  match '/admin/roles', :to => 'admin#roles#index'
  match '/profile', :to => 'users#show'
  
end

show.html.erb

<p id="notice"><%= notice %></p>

<p>
  <b>Invoice date:</b>
  <%= @invoice.invoice_date %>
</p>

<p>
  <b>Purchase order:</b>
  <%= @invoice.purchase_order %>
</p>

<p>
  <b>Date sent:</b>
  <%= @invoice.date_sent %>
</p>

<p>
  <b>Paid:</b>
  <%= @invoice.paid %>
</p>

<p>
  <b>Date paid:</b>
  <%= @invoice.date_paid %>
</p>

<p>
  <b>Sub total:</b>
  <%= @invoice.sub_total %>
</p>

<p>
  <b>Vat rate:</b>
  <%= @invoice.vat_rate %>
</p>

<p>
  <b>Vat total:</b>
  <%= @invoice.vat_total %>
</p>

<p>
  <b>Discount total:</b>
  <%= @invoice.discount_total %>
</p>

<p>
  <b>Total:</b>
  <%= @invoice.total %>
</p>

<p>
  <b>Company:</b>
  <%= @invoice.company_id %>
</p>

<%= link_to 'New invoice item', new_invoice_invoice_items_path(@invoice) %>

<table id="invoiceitems">
	<tr>
		<th>Qty</th>
		<th>Price</th>
		<th>Description</th>
		<th>VAT Rate</th>
		<th>Total</th>
	</tr>
<% @items.each do |item| %>
	 <tr>
	 	<td><%= item.quantity %></td>
	    <td><%= item.unit_type %></td>
	    <td><%= item.unit_price %></td>
	    <td><%= item.detail %></td>
	    <td><%= item.vat_rate %></td>
		<td><%= item.total_cost %></td>
	</tr>
<% end %>
</table>


<%= link_to 'Edit', edit_invoice_path(@invoice) %> |
<%= link_to 'Back', invoices_path %>

show.html.erb, line 68, should that read

<% @invoice.items.each do |item| %>

and make invoice.rb, line 7

has_many :items, :class_name => :invoice_items, :dependent => :destroy

Also, is that a stray semi-colon at the end of invoice.rb, line 2?

Also, your InvoiceItems class should really be InvoiceItem it will cause you big problems!