gistfile1.txt

 def add_product(product)
    current_item = line_items.find_by_mnetid(product[:mnetid])
    if current_item
      current_item.errors[:base] << "This is already in your cart"
      #raise "This is already in your cart"
      return false
    else
      current_item = line_items.build(
        :mnetid => product[:mnetid],
        :title => product[:title],
        :artist => product[:artist],
        :price => product[:price].to_f
      )
    end
    current_item
  end