为什么在保存对象后使用“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

我正在编写 Hartl 的 Rails 4 教程第 6 章的练习.第一个练习测试以确保用户电子邮件地址正确小写:

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

我不明白为什么这里需要重新加载"方法.一旦将@user.email 设置为mixed_case_email 和saved 的内容，就不是@user.reload.email 和 @user.email 是一回事吗?我把 reload 方法拿出来尝试一下，它似乎没有改变任何测试.

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.

我在这里遗漏了什么?

推荐答案

在这种情况下是的 @user.reload.email 和 @user.email 是一回事.但是使用 @user.reload.email 而不是 @user.email 来检查数据库中保存的内容是一种很好的做法，我的意思是你不知道或者有人在 after_save 中添加了一些代码来改变它的值，那么它不会对你的测试产生影响.

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.

而且您要检查的是数据库中保存的内容，因此 @user.reload.email 准确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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