lib/has_meta_data.rb
module HasMetaData
def self.included(base)
base.extend ClassMethods
end
module ClassMethods
def has_meta_data(options = {}, &block)
return if self.included_modules.include?(HasMetaData::InstanceMethods)
include HasMetaData::InstanceMethods
cattr_accessor :meta_data_class_name, :meta_data_foreign_key, :meta_data_table_name, :meta_data_columns
self.meta_data_class_name = options[:class_name] || 'Meta'
self.meta_data_foreign_key = options[:foreign_key] || self.to_s.foreign_key
self.meta_data_table_name = options[:table_name] || "#{table_name_prefix}#{self.name.demodulize.underscore}_meta#{table_name_suffix}"
# Create Relationship to Meta Data
class_eval do
has_one :meta,
:class_name => "#{self.to_s}::#{meta_data_class_name}",
:foreign_key => meta_data_foreign_key,
:dependent => :destroy
scope :with_meta, lambda { includes(:meta).where("#{meta_data_table_name}.id IS NOT NULL") }
scope :without_meta, lambda { includes(:meta).where("#{meta_data_table_name}.id IS NULL") }
end
# Dynamically Create Model::Meta Class
const_set(meta_data_class_name, Class.new(ActiveRecord::Base))
meta_data_class.cattr_accessor :original_class
meta_data_class.original_class = self
meta_data_class.table_name = meta_data_table_name
# Draft Parent Association
meta_data_class.belongs_to self.to_s.demodulize.underscore.to_sym, :class_name => "::#{self.to_s}", :foreign_key => meta_data_foreign_key
# Block extension
meta_data_class.class_eval(&block) if block_given?
# Finally setup attribute delegation to the meta fields
self.meta_data_columns = meta_data_class.content_columns.map(&:name)
meta_data_columns.each do |field|
define_method(field.to_sym) do
meta.send(field.to_sym) if has_meta_data?
end
define_method("#{field}=".to_sym) do |value|
self.build_meta unless has_meta_data?
meta.send("#{field}=".to_sym, value)
end
end
end
def meta_data_class
const_get(meta_data_class_name)
end
end
module InstanceMethods
def has_meta_data?
!self.meta.nil?
end
end
end
require "has_meta_data/railtie"