Work env:
Rails 4.1.4
mongoid 4.0.0

Below is my devise model

class User
field :first_name, type: String, default: ""
field :last_name, type: String, default: ""
include Mongoid::Document
belongs_to :user_info, polymorphic: true
end

class Employee
include Mongoid::Document
belongs_to: :company
has_one :user, class_name: 'User', as: :user_info, dependent: :destroy
end

Below in my query that results into a nil in-spite object being present:

@employee = @company.employees

Now if i get first_name of each employee, results into nil
e.g.

@user = User.where(user_info: @employees.first)
@employee = @employees.first.user # this return null

It fires below query and results in nil:

MOPED: 127.0.0.1:27017 QUERY database=quikchex_v2_development collection=users selector=

{"user_info_id"=>BSON::ObjectId('53d88cbf4e696b0bc2020000')}

flags=[] limit=0 skip=0 batch_size=nil fields=nil runtime: 0.3662ms

If I fire same query on mongo prompt i get the ouput:

db.users.find(

{user_info_id: '53d88cbf4e696b0bc2020000'}

)

{ "_id" : ObjectId("53d88cbc4e696b0bc2000000"), "first_name" : "Nikunj", "last_name" : "Thakkar", "user_info_id" : "53d88cbf4e696b0bc2020000", "user_info_type" : "Employee" }

Edit:
I tried a below native query and it returns me the employee object:
User.collection.find(

{user_info_id: '53d88cbf4e696b0bc2020000'}

)

The issue then is mongoid converts the user_info_id to BSON::ObjectId('53d88cbf4e696b0bc2020000') while querying, which it shouldn't

Any help is welcome.
Thanks