How to fix / debug 'expected x.rb to define X.rb' in Rails

Question

I have seen this problem arise in many different circumstances and would like to get the best practices for fixing / debugging it on StackOverflow.

To use a real world example this occurred to me this morning:

expected announcement.rb to define Announcement

The class worked fine in development, testing and from a production console, but failed from in a production Mongrel. Here's the class:

class Announcement < ActiveRecord::Base
  has_attachment :content_type => 'audio/mp3', :storage => :s3
end

The issue I would like addressed in the answers is not so much solving this specific problem, but how to properly debug to get Rails to give you a meaningful error as expected x.rb to define X.rb' is often a red herring...

Edit (3 great responses so far, each w/ a partial solution)

Debugging:

1. From Joe Van Dyk: Try accessing the model via a console on the environment / instance that is causing the error (in the case above: script/console production then type in 'Announcement'.

2. From Otto: Try setting a minimal plugin set via an initializer, eg: config.plugins = [ :exception_notification, :ssl_requirement, :all ] then re-enable one at a time.

Specific causes:

1. From Ian Terrell: if you're using attachment_fu make sure you have the correct image processor installed. attachment_fu will require it even if you aren't attaching an image.

2. From Otto: make sure you didn't name a model that conflicts with a built-in Rails class, eg: Request.

3. From Josh Lewis: make sure you don't have duplicated class or module names somewhere in your application (or Gem list).

Answer 1

That is a tricky one.

What generally works for me is to run "script/console production" on the production server, and type in:

Announcement

That will usually give you a better error message. But you said you already tried that?

Answer 2

I just ran into this error as well.

The short of it was that my rb file in my lib folder was not in a folder structure to match my module naming convention. This caused the ActiveSupport auto loader to use the wrong module to see if my class constant was defined.

Specifically I had defined the following class

module Foo
  class Bar
  end
end

In the root of /lib/bar.rb

This caused the autoloader to ask module Object if Bar was defined instead of module Foo.

Moving my rb file to /lib/foo/bar.rb fixed this problem.

Answer 3

I've encountered this before, and the AttachmentFu plugin was to blame. I believe in my case it was due to AttachmentFu expecting a different image processor than what was available, or non-supported versions were also installed. The problem was solved when I explicitly added :with => :rmagick (or similar -- I was using RMagick) to the has_attachment method call even for non-image attachments. Obviously, make sure that your production environment has all the right gems (or freeze them into your application) and supporting software (ImageMagick) installed. YMMV.

As for not getting Rails and AttachmentFu to suck up and hide the real error -- we fixed it before figuring it out completely.

Answer 4

Since this is still the top Google result, I thought I'd share what fixed the problem for me:

I had a module in the lib folder with the exact same name as my application. So, I had a conflict in module names, but I also had a conflict of folder names (not sure if the latter actually makes a difference though).

So, for the OP, make sure you don't have duplicated class or module names somewhere in your application (or Gem list).

Answer 5

For me, the cause was a circular dependency in my class definitions, and the problem only showed up using autotest in Rails. In my case, I didn't need the circular dependency, so I simply removed it.

Answer 6

You can try disabling all your plugins and add them back in one by one.

In environment.rb in the Initalizer section, add a line like this one:

config.plugins = [ :exception_notification, :ssl_requirement, :all ]

Start with the minimum set to run your application and add them in one by one. I usually get this error when I've defined a model that happens to map to an existing filename. For example, a Request model but Rails already has a request.rb that gets loaded first.