user 类：

class Delta::User < ActiveRecord::Base
  has_many :orders, dependent: :destroy

order 类：

class Delta::Order < ActiveRecord::Base
  belongs_to :user
  has_one "product"

测试数据：

user1=Delta::User.new
user1.id=1
user1.username="tom"


p1=Delta::Product.new
p1.price=100
p1.id=1

p2=Delta::Product.new
p2.price=200
p2.id=2

order1=Delta::Order.new
order1.user_id=1
order1.product_id=2
order1.num=2

puts "==="
puts Delta::Order.vip_total_consumption

vip_total_consumption 代码如下：

def self.vip_total_consumption
    total = 0.0
    Delta::User.where(username: 'tom').each do |us|
      puts us.orders.length
      us.orders.each do |order|
        total += order.num*order.product.price
      end
    end
    return total
  end

但是 puts us.orders.length 这句话没有打印出 数量 1 而是 0 请问哪里的问题？？？