class Invoice < ActiveRecord::Base belongs_to :supplier belongs_to :delivery belongs_to :order validates_presence_of :supplier_id validates_numericality_of :amount, :deposit, :deposit_credit scope :unpaid, :conditions => { :paid_on => nil } # Replace numeric seperator with database format localize_input_of :amount, :deposit, :deposit_credit # Amount without deposit def net_amount amount - deposit + deposit_credit end end