Rails3とRails4のhas_manyオプションの差分を吸収する

Rails3とRails4の違いの1つに has_many のオプションがあります。

	# Rails3
	class Course < ActiveRecord::Base
	has_many :students, order: :name, include: [:parents, :brothers], dependent: :destroy
	end
	# Rails4
	class Course < ActiveRecord::Base
	has_many :students, ->{ order(:name).includes(:parents, :brothers) }, dependent: :destroy
	end

view raw has_many_before.rb hosted with ❤ by GitHub

Rails4では order と include が使えなくなってるんですね。

しかし、1つのソースでRails3とRails4に対応したい場合どうしようか？

	module AssocOpts
	extend ActiveSupport::Concern
	module ClassMethods
	def assoc_opts(options)
	return [options] if Gem::Version.new(Rails.version) < Gem::Version.new('4.0.0')
	order_option = options.delete(:order)
	include_option = options.delete(:include)
	if order_option && include_option
	[Proc.new { order(order_option).includes(include_option) }, options]
	elsif order_option
	[Proc.new { order(order_option) }, options]
	elsif include_option
	[Proc.new { includes(include_option) }, options]
	else
	[options]
	end
	end
	end
	end

view raw assoc_opts.rb hosted with ❤ by GitHub

	# Rails3 and Rails4
	class Course < ActiveRecord::Base
	include AssocOpts
	has_many :students, *assoc_opts(order: :name, include: [:parents, :brothers], dependent: :destroy)
	end

view raw has_many_after.rb hosted with ❤ by GitHub

とまあこんな感じでどうでしょう？