Ruby on rails - where子句在关系上产生'undefined method'错误

我有一个模型Email_address属于用户。而在我的用户模型中，它表示has_many email_addresses。请看下面的控制台输出：Ruby on rails - where子句在关系上产生'undefined method'错误

irb(main):073:0>b = EmailAddress.find(2)

EmailAddress Load (0.4ms) SELECT email_addresses.* FROM email_addresses WHERE email_addresses.id = 2 LIMIT 1

=> #EmailAddress id: 2, email: "[email protected]", user_id: 2, created_at: "2013-03-06 02:33:40", updated_at: "2013-03-06 02:33:40"

irb(main):074:0>b.user

User Load (0.1ms) SELECT users.* FROM users WHERE users.id = 2 LIMIT 1

=> #User id: 2, username: "w", created_at: "2013-03-06 02:33:40", updated_at: "2013-03-06 02:33:40"

irb(main):075:0>b = EmailAddress.where(:email => "[email protected]")

EmailAddress Load (0.1ms) SELECT email_addresses.* FROM email_addresses WHERE email_addresses.email = [email protected]

=> #EmailAddress id: 1, email: "[email protected]", user_id: 1, created_at: "2013-03-05 07:26:56", updated_at: "2013-03-05 07:26:56"

irb(main):076:0>b.user

NoMethodError: undefined method user for # from /var/lib/gems/1.8/gems/activerecord-3.2.11/lib/active_record/relation/delegation.rb:45:in `method_missing' from (irb):76

谁能告诉我，为什么当我使用where()我无法再找到用户，但它的作品，当我使用find（）方法？这是非常令人困惑的输出。

来源

2013-03-06 user985723

'EmailAddress.where（：电子邮件=> “[email protected]”）'产生一个' ActiveRecord ::关系对象。尝试将其更改为EmailAddress.where（：email =>“[email protected]”）。首先' – jvnill 2013-03-06 03:23:13

宾果！谢谢jvnill！这是完美的。 – user985723 2013-03-06 03:26:01

尽量使用“范围”而不是在控制器中使用“where”，因为它使代码更具可读性/可维护性。在这里阅读更多关于范围http://guides.rubyonrails.org/active_record_querying.html#scopes – sameera207 2013-03-06 03:47:35

.where()返回数组（具体为ActiveRecord::Relation）。要选择返回的对象，您需要指定哪个对象。在这种情况下，因为你希望一个对象，你可以这样做：

b = EmailAddress.where(:email => "[email protected]").first

b = EmailAddress.where(:email => "[email protected]")[0]

来源

2013-03-06 03:29:48 AdamT

Ruby on rails - where子句在关系上产生'undefined method'错误

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