Создание Категорий и подкатегорий

gistfile1.txt

rails g model category name:string parent:references

class Category < ActiveRecord::Base
  has_many :subcategories, :class_name => "Category", :foreign_key => "parent_id", :dependent => :destroy
  belongs_to :parent_category, :class_name => "Category"
end

def index
  @category = nil
  @categories = Category.find(:all, :conditions => {:parent_id => nil } )
end

# Show subcategory
def show
  # Find the category belonging to the given id
  @category = Category.find(params[:id])
  # Grab all sub-categories
  @categories = @category.subcategories
  # We want to reuse the index renderer:
  render :action => :index
end

def new
  @category = Category.new
  @category.parent = Category.find(params[:id]) unless params[:id].nil?
end 

<h1><%= @category.nil? ? 'Main categories' : category.text %></h1>
<table>
<% @categories.each do |category| %>
<tr>
  <td><%= link_to category.text, category_path(category) %></td>
  <td><%= link_to 'Edit', edit_category_path(category) unless category.parent.nil? %></td>
  <td><%= link_to 'Destroy', category_path(category), :confirm => 'Are you sure?', :method => :delete unless category.parent.nil? %></td>
</tr>
<% end %>
</table>
<p>
  <%= link_to 'Back', @category.parent.nil? ? categories_path : category_path(@category.parent) unless @category.nil? %>
  <%= link_to 'New (sub-category', new_category_path(@category) unless @category.nil? %>
</p>