ruby script/plugin install git://github.com/caring/acts_as_url_param.git

The URL parameter value that is computed will be unique within the model. If the model is using inheritance, it's recommended to define acts_as_url_param on the base class.

Defines one public class methods on your model:

MyResource.url_param_available?(candidate,id=nil)
# => true
# if the candidate value does not exist for the model

Defines one public instance method on your model:

my_resource.compute_url_param
# => "unique-url-parameter-2"

Example
=======

# use the url_param column as the model's url. It will be set and/or modified whenever the default method changes.
# The default methods, in order of precedence, are: :name, :label, :title
class MyResource < ActiveRecord::Base
  acts_as_url_param
end

# use the url_name column as the model's url. It will be set and/or modified whenever title changes
class MyResource < ActiveRecord::Base
  acts_as_url_param :url_name, :from => :title
end

# use the url_param column as the model's url. It will be set and/or modified whenever title changes
class MyResource < ActiveRecord::Base
  acts_as_url_param :from => :title
end

# use the url_param column as the model's url. It will be set and/or modified whenever the :on event occurs.
# Allowed events are: :create, :save, :update. Default is :create so that your permalinks stay permanent.
# May also be a Proc that accepts the model instance and returns true if url_param should change.
class MyResource < ActiveRecord::Base
  acts_as_url_param :from => :title, :on => :create
end

# use the url_name column as the model's url. It will be set and/or modified whenever the :on event(s) occur.
class MyResource < ActiveRecord::Base
  acts_as_url_param :url_name, :from => :title, :on => :create
end

# Passing a block allows you to approve candidate url parameters.
# This enables definition of a url space across that spans several models. This is easiest if all
# models are acts_as_url_param.
class MyResource < ActiveRecord::Base
  acts_as_url_param :url_name, :from => :title do |candidate|
    MyResource.url_param_available?(candidate,self.id) &&
    MyOtherResource.url_param_available?(candidate)
  end
end

There is currently no advanced documentation for this plugin.