Question

i have two models Vote and Option,each with column "total" and "quantity".
(Vote has_many:options)

I want to implement like this initially:

Option.quantities.each{ |quantity| total+=quantity}

Vote.total=total

how to implement that??

Answer 1

Are you asking for an alternate implementation? Or for something else? You can do the same thing with Enumerable::inject, for example:

class Vote < ActiveRecord::Base
  has_many :options
  def calculate_total
    total = self.options.inject(0) { |sum, vote| sum += vote.quantity }
    save!
  end
end

In this way, the Vote total is calculated and saved every time calculate_total is called.