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Series: Plug-in arsenal - Paginating Find

Oh, pagination. How you have been tormented over the years in the Rails community. For those of you who have no idea what the devil pagination is, run a search on Google and take a look at near the bottom of the page – You should see “previous” and “next” links, alongside numbers of pages with which to jump to. That’s pagination!

I believe the majority of current opinion on paginating through records is to avoid using the Rails 1.0 built-in Pagination class. In Rails 2.0, it’s been removed and requires the install of an additional plug-in to receive the previous functionality. Cue Paginating Find, a plug-in written by Alex Wolfe of Carboard Rocket. I first learned of Paginating Find via Ilya Grigorik’s blog, as he had written some Helpers & View Partials to support it. Let’s jump in, shall we?

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ruby script/plugin install http://svn.cardboardrocket.com/paginating_find

Paginating Find overrides the default ActiveRecord::find method, and allows a new set of options dubbed :page to accompany the familiar :conditions, :order, etc. We’ll use a Bulletin model for our example:

bulletin.rb (Model)

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def self.find_all_using_pagination( options = {} )
  return self.find( :all,
    :page => { 
      :size => options[:number_of_records],
      :current => options[:current_page]
    } )
end

These options are typically provided by GET variables passed through the URL string to the controller. The new :page option requirs two vars, :size & :current. Use :size to dictate how many Bulletin’s should be pulled from the database per page, and :current to state which page we’re currently viewing. For example, if :current is set to 2, and :size is at 10, we would receive Bulletin’s 11-21.

The best part about Paginating Find is that it works transparently. If you don’t provide the :page option in the find() call, Rails will enact a regular find() call and ignore the fact that Paginating Find is even installed.

Further readings:

• Want to display the page numbers, ‘previous’ and ‘next’ links, as well as CSS styling? See Ilya’s Faster Pagination in Rails article.
• Find more info for this plug-in at the Carboard Rocket page.