Can no longer rescue_from ActionController::RoutingError

I verified this with a freshly generated rails app from the master branch. I haven't investigated too far, but at this point the best way I can see to do this in rails 3 is to subclass and swap out the ActionDispatch::ShowExceptions middleware. Or add a route that matches anything...is there a better way?

Put following code in an initializer in a rails3 app.

module ActionDispatch
  class ShowExceptions
    def render_exception(env, exception)
      if exception.kind_of? ActionController::RoutingError
        render(500, 'it was routing error')
      else
        render(500, "some other error")
      end
    end
  end
end

There might be a better way but it works in my quick test.

José, are you sure that your solution actually works? I think it's not working as you can't simply say match "*" to match everything in Rails 3 so far?

I mean, you have to do it like this:

match '/:anything', :to => "home#routing_error", :constraints => { :anything => /.*/ }

I was giving it a bit more thought since yesterday. The solution with match "/:anything" is also not perfect for some people, as it'll override all routes from plugins/engines. I now think that best solution is to use custom rack middleware for handling 404 pages in Rails.

The approach that I have adopted to solve this (for now) is to make a call back into the application (from ActionDispatch::ShowExcpetions#render_exception), specifically to a controller that is there for the purpose of rendering an error page. This has all the benefits of using the layout and styling of the host application. However, if a second exception occurs whilst handling the exception in this way, the original method is called, and the default is rendered.

It is better explained here: http://accuser.cc/posts/1-rails-3-0-exception-handling

For those who would rather copy and paste than read the above... ;)

1. http://gist.github.com/522944
   
2. http://gist.github.com/522924

Here is a gem that may solve this issue: http://github.com/vidibus/vidibus-routing_error

The easiest way for me was to add this very last route:

match ''=> lambda { |env| raise ActionController::RoutingError, env["PATH_INFO"] }

Please ignore my previous comment, it does not work that way. Seems rails had some routes cached, so it seemed to work initially.

Automatic cleanup of spam.

Personally, I'm waiting for an Official solution from the Rails Core Team. Until then I need a simple, no side effect solution for catching rogue routes. For now, my solution is an elaboration on José Valim's recommendation:
http://techoctave.com/c7/posts/36-rails-3-0-rescue-from-routing-err...

With this approach, you'll be in unison with the Rails Core Team. Moreover, I incorporate Rails 3 Route Globbing, so you get the added benefit of knowing exactly which rogue route was entered. As a result, you're free to handle routing errors as creatively as you'd like.

Issue for more than just rescuing from routing errors, CanCan::AccessDenied too:

http://www.tonyamoyal.com/2010/07/28/rails-authentication-with-devi...

This is a huge bug and I feel it's priority should be raised.

It's not acceptable for a broken link in a production app to result in a blank screen, this is why we make 404 handlers. But once the request is dispatched to rails it seems to be rails job to render the 404 page, which it can't do because of this bug.

Just to add,
match '/:anything', :to => "home#routing_error", :constraints => { :anything => /./ } or
match "", :to => "home#routing_error"

Don't seem to work when the controller exists but the action doesn't. Exception log still just shows "AbstractController::ActionNotFound (The action 'rejsasdf' could not be found for HomeController):" and a blank page is rendered.

Are you using :action as the dynamic segment name? If so Rails will try to find the action in the controller. The following path works for me:

match '*path', :to => 'errors#not_found'

This won't catch a missing root path - but I'm guessing you're website is there.

I am using non-restful routes, which is perhaps why the catch-all doesn't work for me

match ':controller(/:action(/:id))', :constraints => {:id => /.*/}