How can I cache a calculated column in rails?

Question

I have a tree of active record objects, something like:

class Part < ActiveRecord::Base
  has_many :sub_parts, :class_name => \"Part\"

  def complicat         


        

Answer 1

Have a field similar to a counter cache. For example: order_items_amount and have that be a cached calculated field.

Use a after_save filter to recalculate the field on anything that can modify that value. (Including the record itself)

Edit: This is basically what you have now. I don't know of any cleaner solution unless you wanted to store cached calculated fields in another table.