как связать 2 таблички из монги на рельсах через айдишник?

 

коллекция locations

{
    "_id" : ObjectId("222d1a2980401829b6a74912"),
    "state" : "Россия",
    "district" : "Томская область"
}

коллекция users

{
    "_id" : ObjectId("61dd3a2280401819b6a74912"),
    "name" : "Игорь",
    "number" : 2,
    "location_id" : ObjectId("222d1a2980401829b6a74912")
}

модель Location

class Location
  include Mongoid::Document
  include Mongoid::Timestamps
  field :state, type: String
  field :district, type: String
 # belongs_to :user, inverse: :location
end

модель User

class User
  include Mongoid::Document
  include Mongoid::Timestamps
  #store_in collection: "user"            
  field :name, type: String
  field :number, type: String
  belongs_to :location , class_name: Location  #  class_name: Location в моем случае не обязательно

end