has_states

Adds one or more state constraints to an ActiveRecord model, as well as providing common state related functionality to that model

Example

If we have a Page model and want to add three states (draft, review and publishes), we can use has_states to add these:

class Page < ActiveRecord::Base
  has_states :draft, :review, :published
end

This is the equivalent to the following code

class Page < Activerecord::Base
  STATES = [ 'draft', 'review', 'published' ]
  
  validates_inclusion_of :state, :in => STATES
  
  named_scope :draft,     :conditions => { :state => 'draft' }
  named_scope :review,    :conditions => { :state => 'review' }
  named_scope :published, :conditions => { :state => 'published' }
  
  def draft?
    state == 'draft'
  end
  
  def review?
    state == 'review'
  end
  
  def published?
    state == 'published'
  end
  
  def set_draft
    self.state = 'draft'
  end
  
  def set_draft!
    update_attribute :state, 'draft'
  end
  
  def set_review
    self.state = 'review'
  end
  
  def set_review!
    update_attribute :state, 'review'
  end
  
  def set_published
    self.state = 'published'
  end
  
  def set_published!
    update_attribute :state, 'published'
  end
end

Detail

has_states takes a list of states, as well as any additional options (as a hash), for example:

has_states :there_can_be_only_one
has_states :first_state, :second_state
has_states :foo, :bar, :field_name => :awesomeness_state  # the default field_name is :state
has_states :open, :closed, :prefix => 'door_'  # prefixing is useful if there are multiple states

What the options do

1. field_name specifies the field name the state is stored in, by default this is a field called 'state'
2. prefix added a prefix to the named_scopes as well as the boolean accessors, state setters (both instant and normal)

Copyright (c) 2009 James Brooks, released under the MIT license