请按语法排序 Mongoid Scope

Posted 2023-02-15

【中文标题】请按语法排序 Mongoid Scope

【英文标题】：Mongoid Scope order by syntax please

【发布时间】：2011-09-14 09:20:43

【问题描述】：

我用的是最新的mongoid...

我如何做这个名为_scope的活动记录的mongoid等效项：

class Comment
  include Mongoid::Document
  include Mongoid::Timestamps

  embedded_in :post

  field :body, :type => String

  named_scope :recent, :limit => 100, :order => 'created_at DESC'
...
end

【参考方案1】：

必须这样定义

scope :recent, order_by(:created_at => :desc).limit(100)

您可以查看 mongoid 文档以了解范围 here

从页面

命名作用域是在类级别使用作用域宏定义的，并且可以链接起来以在良好的 DSL 中创建结果集。

class Person
  include Mongoid::Document
  field :occupation, type: String
  field :age, type: Integer

  scope :rock_n_rolla, where(occupation: "Rockstar")
  scope :washed_up, where(:age.gt => 30)
  scope :over, ->(limit)  where(:age.gt => limit) 
end

# Find all the rockstars.
Person.rock_n_rolla

# Find all rockstars that should probably quit.
Person.washed_up.rock_n_rolla

# Find a criteria with Keith Richards in it.
Person.rock_n_rolla.over(60)