friendly_id.rb

# encoding: utf-8
require "thread"
require "friendly_id/base"
require "friendly_id/model"
require "friendly_id/object_utils"
require "friendly_id/configuration"
require "friendly_id/finder_methods"

=begin

== About FriendlyId

FriendlyId is an add-on to Ruby's Active Record that allows you to replace ids
in your URLs with strings:

    # without FriendlyId
    http://example.com/states/4323454

    # with FriendlyId
    http://example.com/states/washington

It requires few changes to your application code and offers flexibility,
performance and a well-documented codebase.

=== Core Concepts

==== Slugs

The concept of "slugs[http://en.wikipedia.org/wiki/Slug_(web_publishing)]" is at
the heart of FriendlyId.

A slug is the part of a URL which identifies a page using human-readable
keywords, rather than an opaque identifier such as a numeric id. This can make
your application more friendly both for users and search engine.

==== Finders: Slugs Act Like Numeric IDs

To the extent possible, FriendlyId lets you treat text-based identifiers like
normal IDs. This means that you can perform finds with slugs just like you do
with numeric ids:

    Person.find(82542335)
    Person.find("joe")

=end
module FriendlyId

  # The current version.
  VERSION = "4.0.0.beta14"

  @mutex = Mutex.new

  autoload :History,  "friendly_id/history"
  autoload :I18n,     "friendly_id/i18n"
  autoload :Reserved, "friendly_id/reserved"
  autoload :Scoped,   "friendly_id/scoped"
  autoload :Slugged,  "friendly_id/slugged"

  # FriendlyId takes advantage of `extended` to do basic model setup, primarily
  # extending {FriendlyId::Base} to add {FriendlyId::Base#friendly_id
  # friendly_id} as a class method.
  #
  # Previous versions of FriendlyId simply patched ActiveRecord::Base, but this
  # version tries to be less invasive.
  #
  # In addition to adding {FriendlyId::Base#friendly_id friendly_id}, the class
  # instance variable +@friendly_id_config+ is added. This variable is an
  # instance of an anonymous subclass of {FriendlyId::Configuration}. This
  # allows subsequently loaded modules like {FriendlyId::Slugged} and
  # {FriendlyId::Scoped} to add functionality to the configuration class only
  # for the current class, rather than monkey patching
  # {FriendlyId::Configuration} directly. This isolates other models from large
  # feature changes an addon to FriendlyId could potentially introduce.
  #
  # The upshot of this is, you can have two Active Record models that both have
  # a @friendly_id_config, but each config object can have different methods
  # and behaviors depending on what modules have been loaded, without
  # conflicts.  Keep this in mind if you're hacking on FriendlyId.
  #
  # For examples of this, see the source for {Scoped.included}.
  def self.extended(model_class)
    return if model_class.respond_to? :friendly_id
    class << model_class
      alias relation_without_friendly_id relation
    end
    model_class.instance_eval do
      extend Base
      @friendly_id_config = Class.new(Configuration).new(self)
      FriendlyId.defaults.call @friendly_id_config
    end
  end

  # Set global defaults for all models using FriendlyId.
  #
  # The default defaults are to use the +:reserved+ module and nothing else.
  #
  # @example
  #   FriendlyId.defaults do |config|
  #     config.base = :name
  #     config.use :slugged
  #   end
  def self.defaults(&block)
    @mutex.synchronize do
      @defaults = block if block_given?
      @defaults ||= lambda {|config| config.use :reserved}
    end
  end
end