关于范围的 Ruby on Rails 问题

发布于 2024-11-04 21:53:53 字数 581 浏览 2 评论 0原文

我的模型中有以下命名范围

class User
  scope :single_action, where("parent_id = ?", nil)
end

即使有parent_id 值为 nil 的记录，它们似乎也不可用。

ruby-1.9.2-p0 > User.select("name")
 => [#<User parent_id: nil, name: "John">, #<Task parent_id: 1, name: "Felix">, #<Task parent_id: nil, name: "John Felix">]

我尝试使用活动记录查询来执行相同的操作，但它也返回空结果集

ruby-1.9.2-p0 > User.where("parent_id = ?",nil)
 => []

我定义了一些其他范围，这些范围似乎工作正常。我的Rails版本是3.0.7，Ruby版本是Ruby 1.9.2 你能帮我解决这个问题吗？

谢谢：）

原文

I have the following named scope in my model

class User
  scope :single_action, where("parent_id = ?", nil)
end

Even though there are records with parent_id with nil values, they do not seem to be available.

ruby-1.9.2-p0 > User.select("name")
 => [#<User parent_id: nil, name: "John">, #<Task parent_id: 1, name: "Felix">, #<Task parent_id: nil, name: "John Felix">]

I tried using the active record query to do the same, but it also returns empty resultset

ruby-1.9.2-p0 > User.where("parent_id = ?",nil)
 => []

I have defined few other scopes which seems to be working fine.
My Rails version is 3.0.7 and Ruby version is Ruby 1.9.2
Could you please help me to solve this problem.

Thanks :)

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北城孤痞 2024-11-11 21:53:53

将其更改为：

User.where(:parent_id => nil)

您可以看到差异（您实际上是在尝试匹配字符串“NULL”，而不是检查值是否为 NULL）：

ruby-1.9.2-p180 :031 > User.where("remember_token = ?", nil)
 => [] 
ruby-1.9.2-p180 :032 > User.where(:remember_token => nil)
 => [#<User id: 232255501, .......

ruby-1.9.2-p180 :029 > User.where(:remember_token => nil).to_sql
 => "SELECT `users`.* FROM `users` WHERE (`users`.`remember_token` IS NULL)" 
ruby-1.9.2-p180 :030 > User.where("remember_token = ?", nil).to_sql
 => "SELECT `users`.* FROM `users` WHERE (remember_token = NULL)

Change that to :

User.where(:parent_id => nil)

You can see the difference (you were actually trying to match the string 'NULL' instead of checking for the value being NULL):

ruby-1.9.2-p180 :031 > User.where("remember_token = ?", nil)
 => [] 
ruby-1.9.2-p180 :032 > User.where(:remember_token => nil)
 => [#<User id: 232255501, .......

ruby-1.9.2-p180 :029 > User.where(:remember_token => nil).to_sql
 => "SELECT `users`.* FROM `users` WHERE (`users`.`remember_token` IS NULL)" 
ruby-1.9.2-p180 :030 > User.where("remember_token = ?", nil).to_sql
 => "SELECT `users`.* FROM `users` WHERE (remember_token = NULL)

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