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Rails, Resources and Permalinks

12 April 2007

There has been quite a bit of discussion about creating permalinks with a rails resource. In this article I will show you how to create permalinks for a resource named ‘pages’ without giving up on any of the resource goodness!

Before I start I’ll presume you have a page scaffold_resource setup in your rails application. Make sure you have at least the following fields in your page model:

t.column :title, :string
t.column :permalink, :string
t.column :content, :text

Okay, what you want is the permalink_fu plugin. This plugin greatly simplifies the act of generating a permalink from a title. Install it first:

cd railsapp
./script/plugin install

In your Page model you may now add the following line. This line will generate a permalink in the permalink attribute automatically, so you don’t have to show the permalink field in any forms.

has_permalink :title

That’s it for generating the appropriate permalink string in your database.

Rails goodness has already provided you with the basic RESTful routes:

But what you really want, is something like:

Notice that the permalink url is only a GET request and should not be used for editing or updating the page in question.

Since using any other identifier than :id in a resource is madness, I create two new routes that will allow me to access permalinked pages. Not only that, but I do maintain the format option. Basically this means that you get three routes:

Notice that I removed the ’s’ from ‘pages’ here. This is to avoid confusion with the resource ‘pages’. But more on that later.

Now in config/routes.rb add the following two lines:

map.permalink 'page/:permalink', :controller => 'pages', :action => 'permalink'
map.connect 'page/:permalink.:format', :controller => 'pages', :action => 'permalink', :format => nil

The first line adds a named route to an action named ‘permalink’ in your PagesController. This gives you the ability to add peralink links easily:


The second link is unnamed, and allows you to specify a format like HTML or XML.

The permalink action looks like this:

# GET /page/perma-link
# GET /page/permal-link.xml
def permalink
  @page = Page.find_by_permalink(params[:permalink])

  respond_to do |format|
    format.html { render :action => 'show' }
    format.xml  { render :xml => @page.to_xml }

This special permalink action uses the same ‘show’ view as your resource.

If you want to maintain the ‘pages’ part of the URL, that’s possible. You’ll have to write a condition that makes sure that the :permalink parameter is a string an not an integer (ID). This article does not cover this.

You may now use permalinks for your pages! Congratulations.