It's time for action arguments in Rails3.

Big thanks go out to: ezmobius, mattetti, maiha, Yehuda Katz, Andy Delcambre, Janne Asmala. Did I miss any merb-action-args contributors?

A plugin for the Rails framework that provides support for arguments to actions that come in from the query.

As a system gem:

gem install rails_action_args

Or in a gemfile:

gem "rails_action_args", "0.1.5"

When installed as a gem:

require "rails_action_args/plugin"

Or as a plugin

script/plugin install git://github.com/collin/rails_action_args.git

class Foo < ApplicationController::Base
  def bar(baz)
    bar
  end
end

Hitting "/foo/bar?baz=bat" will call foo("bat").

Hitting "/foo/bar" will raise an AbstractController::ActionArgs::InvalidActionArgs exception

class Foo < ApplicationController::Base
  def bar(baz, bat = "hola")
    "#{baz} #{bat}"
  end
end

Hitting "/foo/bar?baz=bat" will call foo("bat", "hola")

Hitting "/foo/bar?baz=bat&bat=whaa" will call foo("bat", "whaa")

Hitting "/foo/bar" will still raise a BadRequest.

class Foo < ApplicationController::Base
  def bar(one, two = "dos", three = "tres")
    "#{one} #{two} #{three}"
  end
end

The interesting thing here is that hitting "/foo/bar?one=uno&three=three" will call foo("uno", "dos", "three"). In other words, the defaults can be in any order, and rails_action_args will figure out where to fill in the holes.