cause.rb

module Spree
  class Cause
    has_many :products
    def cumulative_impact
      Spree::LineItem.select("sum((spree_line_items.price * spree_line_items.quantity * (1/spree_line_items.charity_percent::float)))").joins({variant: {product: :cause}}).where(causes: {id: self.id})
    end
  end
end