Question

I have got this structure

class House
  include Mongoid::Document
  embeds_many :inhabitants
end

class Inhabitant
  include Mongoid::Document
  embedded_in :house
  field :name
  field :gender
  field :age
end

I can get all houses where females live:

houses = House.where("inhabitants.gender" => "female")

But how can I get all houses where females under age 50 live? How can I specify more than one condition for embedded object?

Answer 1

To apply multiple conditions to each entry in an array, you should use the $elemMatch operator. I’m not familiar with Mongoid, but here’s the MongoDB shell syntax for your query modified to use $elemMatch:

> db.house.find({inhabitants: {$elemMatch: {gender: "female", age: {$lt: 50}}}})