Custom Error Pages in Rails?

Question

I need to implement a custom error page in my rails application that allows me to use erb.

I've been following this tutorial (http://blog.tommilewski.net/2009/05/custom-error-pages-in-rails/) and I cannot get it to work locally (or remotely). I am running Rails 2.3.5

Here's the gist of the approach.

1) in the 'application_controller', I over ride the "render_optional_error_file(status_code)" method, and set the visibility to "protected", like this.

protected

def render_optional_error_file(status_code)
  known_codes = ["404", "422", "500"]
  status = interpret_status(status_code)

  if known_codes.include?(status_code)
    render :template => "/errors/#{status[0,3]}.html.erb", :status => status, :layout => 'errors.html.erb'
  else
    render :template => "/errors/unknown.html.erb", :status => status, :layout => 'errors.html.erb'
  end
end

def local_request?
  true
end

I also created a folder within views called errors and created the following views: 404.html.erb, 422.html.erb, 500.html.erb,unknown.html.erb and I created a new layout "errors.html.erb"

I can't seem to get it to work. I've been trying to trigger the 404 page by navigating to http://localhost:3000/foobar -- but, instead of getting the new 404.html.erb, I seem to be getting the standard apache 500 error. This happens when I try both mongrel_rails start and mongrel_rails start -e production.

Answer 1

Firstly - have you deleted the file: 'public/500.html' If that file exists, it will override anything else that you try to do.

Secondly, using an explicit "rescue_from" in the controller (as explained in the other comment) - is a good option if you need to fine-tune the response to different kinds of errors.

Answer 2

Purpose of completeness for newer rails versions:

http://www.frick-web.com/en/blog/nifty_errorpages-gem

that is a little rails engine for handling your error pages. Maybe you will need it for newer projects. it is a good option to handle errors in my opinion.

Answer 3

You most likely get the 500 error because of an application error. Have you checked the log files?

Update:

Are you certain that you are running 2.3.5 and not an older version that happens to be installed? Mongrel should say which version you are running when it starts, otherwise it should say in the config/environment.rb file.

There are some errors in the code that might create the 500 error. I've changed that and also corrected a few other things I think you meant :)

def render_optional_error_file(status_code)
  known_codes = ["404", "422", "500"]
  status = interpret_status(status_code)

  if known_codes.include?(status) # Here it should be status, not status_code (which is a symbol)
    render :template => "errors/#{status[0,3]}", :status => status, :layout => 'errors' # No need to mention ".html.erb", you can do it, but it is not necessary since rails will guess the correct format.
  else
    render :template => "errors/unknown", :status => status, :layout => 'errors'
  end
end

def local_request?
  # This must return false instead of true so that the public viewer is called 
  # instead of the developer version.
  false 
end

Answer 4

I would suggest using exceptions to render such error pages, so you can use inheritance to group your error messages...

First, declare some (I usually do it in application_controller.rb)

class Error404 < StandardError; end
class PostNotFound < Error404; end

Then add code to ApplicationController to handle them

class ApplicationController < ActionController::Base

  # ActionController::RoutingError works in Rails 2.x only.
  # rescue_from ActionController::RoutingError, :with => :render_404
  rescue_from Error404, :with => :render_404
  rescue_from PostNotFound, :with => :render_post_not_found


  def render_404
    respond_to do |type| 
      type.html { render :template => "errors/error_404", :status => 404, :layout => 'error' } 
      type.all  { render :nothing => true, :status => 404 } 
    end
    true
  end

  def render_post_not_found
    respond_to do |type| 
      type.html { render :template => "errors/shop_not_found", :status => 404, :layout => 'error' } 
      type.all  { render :nothing => true, :status => 404 } 
    end
    true
  end
end

This renders errors/error_404 with the errors layout. Should get you started :)

And in your target_controller:

raise PostNotFound unless @post

---

Edit

Note for Rails 3

for a longer explanation on why ActionController::RoutingError doesn't work for rails 3: Rails 3.0 Exception Handling.

Rails ticket 4444

"If your application relies on engines that extend your app with their own routes, things will break because those routes will never get fired!"