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rails--rails/activemodel/lib/active_model/conversion.rb

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1.4 KiB
Ruby

module ActiveModel
# == Active Model Conversions
#
# Handles default conversions: to_model, to_key and to_param.
#
# == Example
#
# 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 == self # => true
# cm.to_key # => nil
# cm.to_param # => nil
#
module Conversion
# If your object is already designed to implement all of the Active Model
# you can use the default to_model implementation, which simply returns
# self.
#
# 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.
#
# Note the default implementation uses persisted? just because all objects
# in Ruby 1.8.x responds to :id.
def to_key
persisted? ? [id] : nil
end
# Returns a string representing the object's key suitable for use in URLs,
# or nil if persisted? is false
def to_param
persisted? ? to_key.join('-') : nil
end
end
end