Graceful 404s in Rails 2.0

by Trevor Turk

With the upcoming Rails 2.0: Preview Release starting to get some attention, I thought I’d take a moment to play with some of the new features. One of my favorite additions is the new exception handling stuff. It works just like a before_filter, so you’ll pick it up straight away.

Action Pack: Exception handling:

Lots of common exceptions would do better to be rescued at a shared level rather than per action. This has always been possible by overwriting rescue_action_in_public, but then you had to roll out your own case statement and call super. Bah. So now we have a class level macro called rescue_from, which you can use to declaratively point certain exceptions to a given action.

The following is quick example you can use to catch 404 Record Not Found errors. It will catch all 404s on your site and display a nice message, instead of an ugly white page of death:

Simply dip into the ApplicationController and add the following code:

class ApplicationController  :record_not_found

  # ...

  def record_not_found
    flash[:notice] = "Sorry, the page you requested was not found."
    redirect_to root_path
  end

  # ...

end

…to display a nice message within your app:

…and there you have it: Easy as Pie(tm) Record Not Found exception handling.

P.S.

This also takes advantage of my favorite tiny addition to Rails, map.root. I didn’t see this mentioned in the release announcement, but it’s covered in the video of the Railsconf Europe ’07 video.

Instead of this:

map.home '', :controller => 'home'

…you can now do this:

map.root :controller => 'home'

It’s not a big change, but it’s just… nice, isn’t it?

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