保存对象后为什么要使用“重新加载"方法? (Hartl Rails Tut 6.30) [英] Why use 'reload' method after saving object? (Hartl Rails Tut 6.30)

问题描述

我正在研究《 Hartl的Rails 4教程》第6章的练习.第一次练习测试是为了确保用户电子邮件地址的大小写正确无误:

I'm working on the exercises for chapter 6 of Hartl's Rails 4 Tutorial. The first exercise tests to make sure that user email addresses are down-cased correctly:

require 'spec_helper'

describe User do
  .
  .
  .
  describe "email address with mixed case" do
    let(:mixed_case_email) { "[e-mail]" }

    it "should be saved as all lower-case" do
      @user.email = mixed_case_email
      @user.save
      expect(@user.reload.email).to eq mixed_case_email.downcase
    end
  end
  .
  .
  .
end

我不明白的是为什么在这里需要'reload'方法.将@user.email设置为mixed_case_email和保存的内容后，@user.reload.email和@user.email是不是一回事?我只是尝试尝试了reload方法，但是测试似乎并没有改变任何东西.

What I don't understand is why the 'reload' method is necessary here. Once @user.email is set to the contents of mixed_case_email and saved, aren't @user.reload.email and @user.email the same thing? I took the reload method out just to try it and it didn't seem to change anything with the test.

我在这里想念什么?

推荐答案

在这种情况下，@user.reload.email和@user.email是同一回事.但是，使用@user.reload.email而不是@user.email来检查数据库中到底保存了什么是一个好习惯，我的意思是您不知道自己是否有人在after_save中添加了一些代码，这些代码会更改其值，因此对您的测试.

Yes in this case @user.reload.email and @user.email is the same thing. But it's good practice to use @user.reload.email instead of @user.email to check what is exactly saved in the database i mean you don't know if you or someone add some code in after_save which changes it's value then it will not have effect on your tests.

另外，您要检查的是数据库中保存的内容，因此@user.reload.email准确地反映了数据库中保存的内容，然后@user.email

And also what you are checking is what's saved in the database so @user.reload.email exactly reflects what's saved in database then @user.email

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