Introducing has_slug for Rails

Posted on 29/12/2008. Filed under: Technology | Tags: , |

Straight from README.rdoc:


Deliciously slugalizing ActiveRecord & your ActionControllers since Rails 2.2

        ./script/plugin install git://
        or git submodule add git:// vendor/plugins/has_slug

has_slug provides an easy way to equip your models with
“permalinks” like so:

        class BlogPost < ActiveRecord::Base
          has_slug(:category, :title)

        post = BlogPost.create(:category => "Time Travelling", :title => "Yatta!")
        # => #<BlogPost id: 1, category: "Time Travelling", title: "Yatta!">

        # => "1-time-travelling-yatta"

That‘s nice. But surely not revolutionary.

So let‘s turn our attention to the controller which should of course
be able to find the record identified by the above “permalink”.
Turns out that Rails kinda does this by default by virtue of calling to_i
on params[:id] when passing it to ActiveRecord. Easy enough..

But wait, there‘s more!

Of course this automatic conversion means that your carefully worded
“2-honey-you-look-great-in-that-dress” could also be accessed
under “2-youre-way-too-fat-for-that-dress-honey”. Not so good. In
fact, just anything matching /^2[W$]/ would lead to BlogPost.find(2).
Besides upsetting your wife and/or mistress, this might obvisouly also
annoy search engines which have a fetish for unique resource itentifiers
(i.e. URIs).

But fear not for it has all been taken care of for you!

        class BlogPostsController < ApplicationController
          rescue_from_slug_mismatch { |item| redirect_to(blog_post_url(item), :status => :moved_permanently) }

          def show
            check_slug!(@post = BlogPost.find(params[:id]), params[:id])

And behold: GET /blog_posts/2-honey-you-look-great-in-that-dress
will render /blog_posts/show.hmtl.erb while GET
will 302
to /blog_posts/2-why-i-love-my-wife.

Even better though, the above example actually still works when written
like this:

        class BlogPostsController < ApplicationController
          def show
            check_slug!(@post = BlogPost.find(params[:id]))

Because awesomely enough, the second parameter to check_slug! defaults to
params[:id] and by default, all ApplicationController descendants are
lovingly wired to rescue you from SlugMismatchErrors by redirecting to

So what are you waiting for? Just has_slug your models and
consider your application awesomified!

Copyright (c) 2008 Niels Ganser, released under the MIT license. Even
though this software is released “as is”, I accept full
responsibility for any bone fractures that might directly result from using
it. So in the case of such spontaneous fracturing, feel free contact my
armada of lawyers to discuss your ridiculously high compensation claims.

All your feature requests / bug reports / patches are belong to github!
Or niels at herimedia dot com..

Shout-out to Christoffer Sawicki & Henrik Nyh for creating Slugalizer,
upon which this plugin was originally based (obsolete since Rails 2.2)!


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One Response to “Introducing has_slug for Rails”

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Looks great, as simple as it could be!
Ill give it a try in my next project, if they let me use permalinks with ids :)

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