Mongoid Question

model Token
  include Mongoid::Document
 
  field :user_id
end
 
model User
  include Mongoid::Document
 
  has_many :tokens
end

# In the Rails console this works...

$ Token.where(user_id: Token.first.user_id).first
#<Token _id: ...>

# I feel tempted to add `belongs_to :user` to the token model, but after doing so...

$ Token.where(user_id: Token.first.user_id).first
nil