If you’re using Mongoid::Paranoia, and you’re running into a problem that looks like this:
/Users/you/.rvm/gems/ruby-1.9.3-p194/gems/origin-1.0.5/lib/origin/extensions/nil_class.rb:30:in `__expanded__': wrong number of arguments (0 for 1) (ArgumentError)
from /Users/you/.rvm/gems/ruby-1.9.3-p194/gems/origin-1.0.5/lib/origin/mergeable.rb:199:in `prepare'
from /Users/you/.rvm/gems/ruby-1.9.3-p194/gems/origin-1.0.5/lib/origin/mergeable.rb:158:in `block in __override__'
from /Users/you/.rvm/gems/ruby-1.9.3-p194/gems/origin-1.0.5/lib/origin/selectable.rb:597:in `block (2 levels) in selection'
from /Users/you/.rvm/gems/ruby-1.9.3-p194/gems/origin-1.0.5/lib/origin/selectable.rb:596:in `each_pair'
from /Users/you/.rvm/gems/ruby-1.9.3-p194/gems/origin-1.0.5/lib/origin/selectable.rb:596:in `block in selection'
from /Users/you/.rvm/gems/ruby-1.9.3-p194/gems/origin-1.0.5/lib/origin/selectable.rb:594:in `tap'
from /Users/you/.rvm/gems/ruby-1.9.3-p194/gems/origin-1.0.5/lib/origin/selectable.rb:594:in `selection'
from /Users/you/.rvm/gems/ruby-1.9.3-p194/gems/origin-1.0.5/lib/origin/mergeable.rb:156:in `__override__'
from /Users/you/.rvm/gems/ruby-1.9.3-p194/gems/origin-1.0.5/lib/origin/selectable.rb:261:in `ne'
from (eval):2:in `ne'
from /Users/you/.rvm/gems/ruby-1.9.3-p194/gems/mongoid-3.0.3/lib/mongoid/paranoia.rb:21:in `block in <module:Paranoia>'
....
It might because you are using version 1.0.5 of the origin gem, which was yanked from rubygems.org yesterday: http://rubygems.org/gems/origin/versions/1.0.5
If that’s the case, you’ll probably want to uninstall bad version:
gem uninstall origin -v 1.0.5
If you’re using Rails 3, you’ll want to make sure that your Gemfile.lock does not refer to origin 1.0.5. You can run “bundle update” or delete your Gemfile.lock and run “bundle” to create a new one.
For more information, take a look at the issue on Github. Good luck!