Question

什么是mongoid / ruby语法：

我想查询Parent，包括所有Children（急切地）搜索某个唯一的Child属性（不是_id）。

class Parent
  include Mongoid::Document
  field :first_name, :type => String
  field :last_name, :type => String

  has_many :children, :class_name => 'Child', :inverse_of => :parent
end

class Child
  include Mongoid::Document
  field :first_name, :type => String
  field :last_name, :type => String

  belongs_to :parent, :class_name => 'Parent', :inverse_of => :children
end

在SQL中，我会写

SELECT p.*, c.*
FROM   Parent p
INNER JOIN Child c
ON     c.parent_id = p._id
WHERE EXISTS (
    SELECT 1 FROM Child c2 WHERE c2.first_name = 'Aaron' AND c2.parent_id = p._id
);

Answer 1

试试这个

children = Child.where(:first_name => "Aaron")
children.each do |child|
   parent = child.parent
end

如果您只需要基于上述条件的发布详细信息，则可以运行此

Parent.includes(:child).where('child.first_name' => "Aaron")

但是对于孩子，你必须再次进行查询。

通过引用文档进行Mongoid查询

1 个答案: