POS-Server/app/models/available_product.rb

class AvailableProduct < ActiveRecord::Base
    
    belongs_to :product
    belongs_to :pointsale
    belongs_to :products_variant_id
    has_many :categories, :through => :product

    audited
    validates :price_sale, :presence => { :message => "Debe especificar el precio de venta para su punto de venta"},  :numericality => { :message => "El precio debe ser mayor que el precio de venta base.", :greater_than => :get_price }, :on => :update_price

 	scope :activos, -> { joins(:product).where( "products.status = 1").order("products.name") }

    protected
    	def get_price
    		product.price_sale
    	end
end