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module ActiveModel
# == Active \Model Conversion
#
# Handles default conversions: to_model, to_key, to_param, and to_partial_path.
#
# Let's take for example this non-persisted object.
#
# class ContactMessage
# include ActiveModel::Conversion
#
# # ContactMessage are never persisted in the DB
# def persisted?
# false
# end
# end
#
# cm = ContactMessage.new
# cm.to_model == cm # => true
# cm.to_key # => nil
# cm.to_param # => nil
# cm.to_partial_path # => "contact_messages/contact_message"
module Conversion
extend ActiveSupport::Concern
# If your object is already designed to implement all of the Active Model
# you can use the default <tt>:to_model</tt> implementation, which simply
# returns +self+.
#
# class Person
# include ActiveModel::Conversion
# end
#
# person = Person.new
# person.to_model == person # => true
#
# If your model does not act like an Active Model object, then you should
# define <tt>:to_model</tt> yourself returning a proxy object that wraps
# your object with Active Model compliant methods.
def to_model
self
end
# Returns an Enumerable of all key attributes if any is set, regardless if
# the object is persisted or not. Returns +nil+ if there are no key attributes.
#
# class Person < ActiveRecord::Base
# end
#
# person = Person.create
# person.to_key # => [1]
def to_key
key = respond_to?(:id) && id
key ? [key] : nil
end
# Returns a +string+ representing the object's key suitable for use in URLs,
# or +nil+ if <tt>persisted?</tt> is +false+.
#
# class Person < ActiveRecord::Base
# end
#
# person = Person.create
# person.to_param # => "1"
def to_param
persisted? ? to_key.join('-') : nil
end
# Returns a +string+ identifying the path associated with the object.
# ActionPack uses this to find a suitable partial to represent the object.
#
# class Person
# include ActiveModel::Conversion
# end
#
# person = Person.new
# person.to_partial_path # => "people/person"
def to_partial_path
self.class._to_partial_path
end
module ClassMethods #:nodoc:
# Provide a class level cache for #to_partial_path. This is an
# internal method and should not be accessed directly.
def _to_partial_path #:nodoc:
@_to_partial_path ||= begin
element = ActiveSupport::Inflector.underscore(ActiveSupport::Inflector.demodulize(self))
collection = ActiveSupport::Inflector.tableize(self)
"#{collection}/#{element}".freeze
end
end
end
end
end
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