Mongoid Query By Referenced Document

Question

What is mongoid/ruby syntax for:

I would like to query for a Parent including all Children (eagerly) searching by some unique Child attribute (not the _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

in SQL, I would write

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

Try this

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

if you need only publication details based on above condition you can run this

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

but for children you have to again make the query.