在rspec中，user.invoices.count显示为0，但它显示它有模型

Question

我正在构建一个用户rspec测试。我有许多发票，我与用户关联。在控制台中，当我执行user.invoices时，它显示发票的散列。但是，当我执行user.invoices.count来获取该用户的发票数量时，结果显示为0。下面是我的代码：

  before(:each) do
    @user = FactoryGirl.build(:user)

    @invoice = FactoryGirl.build(:invoice)
    @invoice.issue_date = "2013-01-01"
    @user.invoices << @invoice

如果我在里面放一个调试器，它会显示count = 0。下面是输出：

(rdb:1) p user.invoices
[#<Invoice id: nil, user_id: 279, issue_date: "2013-01-01", due_date: nil, payment_term: "Net 15", discount: nil, created_at: nil, updated_at: nil, client_id: 140, client_invoice_id: 1, custom_message: nil, sent_to: nil, status: nil, public_id: "1234", grand_total: nil, user_name: nil, company_name: nil, custom_email_message: nil, address_line_one: nil, address_line_two: nil>, 
 #<Invoice id: nil, user_id: 281, issue_date: "2013-01-01", due_date: nil, payment_term: "Net 15", discount: nil, created_at: nil, updated_at: nil, client_id: 141, client_invoice_id: 1, custom_message: nil, sent_to: nil, status: nil, public_id: "1234", grand_total: nil, user_name: nil, company_name: nil, custom_email_message: nil, address_line_one: nil, address_line_two: nil>, 
 #<Invoice id: nil, user_id: 283, issue_date: "2012-01-01", due_date: nil, payment_term: "Net 15", discount: nil, created_at: nil, updated_at: nil, client_id: 142, client_invoice_id: 1, custom_message: nil, sent_to: nil, status: nil, public_id: "1234", grand_total: nil, user_name: nil, company_name: nil, custom_email_message: nil, address_line_one: nil, address_line_two: nil>, 
 #<Invoice id: nil, user_id: 285, issue_date: "2011-01-01", due_date: nil, payment_term: "Net 15", discount: nil, created_at: nil, updated_at: nil, client_id: 143, client_invoice_id: 1, custom_message: nil, sent_to: nil, status: nil, public_id: "1234", grand_total: nil, user_name: nil, company_name: nil, custom_email_message: nil, address_line_one: nil, address_line_two: nil>]
(rdb:1) p user.invoices.count
0

为什么count不能正常工作？这是我想要通过的测试：

 it "should return the correct count of all invoices in the specified year" do
   # there are two invoices in 2013
   user = @user
   user.count_of_invoices_by_year("2013", :total).should == 2
 end

count_of_invoices_by_year使用.count，但它不能正常工作

Answer 1

这是因为发送.count使用计数(*)查询数据库。因为您使用的是FactoryGirl.build，所以数据库中没有记录，所以它返回0。

另请参阅：http://rhnh.net/2007/09/26/counting-activerecord-associations-count-size-or-length，它解释了.size、.length和.count之间的区别。

编辑:下面是如何测试你的方法(这会将记录保存到数据库中，但在测试后它们将被销毁)

before(:each) do
  @user = FactoryGirl.create(:user)

  @invoice = FactoryGirl.create(:invoice)
  @invoice.issue_date = "2013-01-01"
  @invoice.save
  @user.invoices << @invoice
  @user.save