Rails extending ActiveRecord::Base

Question

I've done some reading about how to extend ActiveRecord:Base class so my models would have some special methods. What is the easy way to extend it (step by step tutorial). Thx!

Answer 1

Step 1

module FooExtension
  def foo
    puts "bar :)"
  end
end

Step 2

ActiveRecord::Base.send :include, FooExtension

Step 3

There is no step 3 :)

Answer 2

There are two approaches to this:

Monkey patching

Create a file in the config/initializers directory called active_record_monkey_patch.rb.

class ActiveRecord::Base        
  def bar
   "foo"
  end

  def self.find_values opts
    sql = self.send(:construct_finder_sql, opts)
    self.connection.select_values(sql)
  end
end

Modules

Create a file called app_util.rb in the lib directory.

module MyActiveRecordExtensions
    def self.included(base)
      base.extend(ClassMethods)
    end

    # add your instance methods here
    def bar
       "foo"
    end

    module ClassMethods
      # add your static(class) methods here
      def find_values opts
        sql = self.send(:construct_finder_sql, opts)
        self.connection.select_values(sql)
      end
   end
 end
 # include the extension 
 ActiveRecord::Base.send(:include, MyActiveRecordExtensions)

Include the file at the end of your config/environment.rb file.

require "app_util"

Answer 3

You can just extend the class and simply use inheritance.

class AbstractModel < ActiveRecord::Base  
  self.abstract_class = true
end

class Foo < AbstractModel
end

class Bar < AbstractModel
end