Ruby on rails - where子句在關係上產生'undefined method'錯誤

我有一個模型Email_address屬於用戶。而在我的用戶模型中，它表示has_many email_addresses。請看下面的控制檯輸出：Ruby on rails - where子句在關係上產生'undefined method'錯誤

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

誰能告訴我，爲什麼當我使用where()我無法再找到用戶，但它的作品，當我使用find（）方法？這是非常令人困惑的輸出。

來源

2013-03-06 user985723

'EmailAddress.where（：電子郵件=> 「[email protected]」）'產生一個' ActiveRecord ::關係對象。嘗試將其更改爲EmailAddress.where（：email =>「[email protected]」）。首先' – jvnill 2013-03-06 03:23:13

賓果！謝謝jvnill！這是完美的。 – user985723 2013-03-06 03:26:01

儘量使用「範圍」而不是在控制器中使用「where」，因爲它使代碼更具可讀性/可維護性。在這裏閱讀更多關於範圍http://guides.rubyonrails.org/active_record_querying.html#scopes – sameera207 2013-03-06 03:47:35

.where()返回數組（具體爲ActiveRecord::Relation）。要選擇返回的對象，您需要指定哪個對象。在這種情況下，因爲你希望一個對象，你可以這樣做：

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

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

來源

2013-03-06 03:29:48 AdamT

Ruby on rails - where子句在關係上產生'undefined method'錯誤

回答

相關問題