has_paginate

Instalation

Install the plugin with script/plugin install git://github.com/fnando/has_paginate.git

Usage

This plugins uses the named scope feature introduced by Ruby on Rails 2.1 to provide pagination. The result will be :limit + 1, so we'll be able to know if there is a next page without querying the database for count, which causes performance issues on large databases. The default is 10 items per page.

User.paginate                             #=> :offset => 0, :limit => 11
User.paginate(:page => 2)                 #=> :offset => 10, :limit => 11
User.paginate(:page => 2, :limit => 15)   #=> :offset => 15, :limit => 16
@user.things.paginate(:page => params[:page])

After retrieving the results you can display it by using the each_paginate method.

<% each_paginate @users do |user, i| %>
  <%= user.name %>
<% end %>

<% each_paginate @users, :limit => 12 do |user, i| %>
  <%= user.name %>
<% end %>

To display the pagination, use the paginate helper.

# general usage
# path = String/Proc
# options = Hash
<%= paginate @users, path, options %>
<%= paginate @users, options={} %>

<%= paginate @users %> #=> this will set path to request.request_uri
<%= paginate @users, users_path %>
<%= paginate @users, users_path, :page => params[:page] %>
<%= paginate @users, users_path, :page => params[:page], :limit => 10 %>
<%= paginate @users, users_path, :next_label => 'Recent' %>
<%= paginate @users, users_path, :previous_label => 'Older' %>
<%= paginate @users, users_path, :param_name => :p %>
<%= paginate @users, users_path, :show_page => true %>
<%= paginate @users, users_path, :show_disabled => false %>
<%= paginate @users, :url => users_path %>
<%= paginate @users, :url => proc {|page| users_path(page) }%>

You can set properties globally.

class ApplicationController < ActionController::Base
  Paginate.settings = {
    :next_label => 'Next page',
    :previous_label => 'Previous page',
    :param_name => :page,
    :show_disabled => true,
    :show_page => true, 
    :limit => 10,
    :format => 'Page %d'
  }
end

Additionaly, you have a new method called find_in_chunks, that retrieves all records by making multiple queries, instead of using User.all, which consumes lots of memory. This is specially great when you need to iterate a table for doing background jobs.

The example below will query the database 10 times if it has 100 records, returning 10 records for each query.

User.find_in_chunks(:conditions => {:active => true}) do |user|
  user.recount_score!
end

This plugins adds a helper method to the named scope called items? that verifies if the collection is not empty.

<% if @users.items? %>
    <!-- display the collection -->
<% else %>
    <p>Sorry! No users found!</p>
<% end %>

Copyright (c) 2008 Nando Vieira, released under the MIT license