Reorderable

Allows drag-n-drop reordering of ActiveRecord model items when using MySQL or PostgreSQL and jQuery.

Installation

Add the following to your Gemfile:

gem 'reorderable', "~> 0.2"

then run

bundle install

Add a file called reorderable.rb to your config/initializers directory with one of the following lines (depending on your database adapter):

require 'reorderable/active_record/mysql'
require 'reorderable/active_record/postgresql'

Usage

Models

Add the 'reoderable' declaration to any model you want to be reorderable, e.g.

# app/models/page.rb
class Page < ActiveRecord::Base
  reorderable
end

This gem depends on the sortable gem; the options you can pass to 'reorderable' are the same that you can pass to 'sortable'. The 'reorderable' delcaration further sets up a default scope for your model, so that items are properly ordered by default.

Routes

Add a 'reorder' entry to your routes

# config/routes.rb
namespace :admin do
  resources :pages do
    post :reorder, :on => :collection
  end
end

It's possible to dynamically add a route (see: http://openhood.com/rails/rails%203/2010/07/20/add-routes-at-runtime-rails-3/ for one such solution) or to have a reorderings_controller in this gem, but it wasn't clear whether either of those options were really worth it.

Controller

Add the following to any controller you want to have reordering facilities:

# app/controllers/admin/pages_controller.rb
class Admin::PagesController < Admin::BaseController
  include Reorderable::ActionController
end

View

You probably want something like this:

# app/views/admin/pages/index.html.erb
<table>
  <thead>
    <tr>
      <th>&nbsp;</th>
      <th>Name</th>
    </tr>
  </thead>
  <tbody<%= reorderable_attributes(@pages, 'position')%>>
    <% @pages.each do |page| %>
      <tr id='<%= dom_id(page) %>'>
        <td class='move'>&#8597;</td>
        <td><%= page.name %></td>
      </tr>
    <% end %>
  </tbody>
</table>

The key bit is the "reorderable_attributes" helper method, which adds the proper HTML attributes to the element such that the jQuery code can do an Ajax request to the server to reorder the items in the table.

Layout

Add the following to your layout file:

# app/views/layouts/application.html.erb
<%= javascript_include_tag 'jquery-ui-1.8.6.custom.min.js' %>
<%= javascript_include_tag 'reorderable' %>

Note that you must already have jQuery included for this to work!

onedesign/reorderable