This trick works with "has_many" relation, but fails with "embeds_many". Any ideas?

    
    class Country
        include Mongoid::Document

        field :name, type: String
        embeds_many :cities  
    end

    class City
        include Mongoid::Document

        field :name, type: String
        field :full_name, type: String, default: ->{ "#{name}, #{country.name}" }
        embedded_in :country
    end

1.9.3p392 :025 > c = Country.find_or_create_by(name: 'foo')
=> #<Country _id: foo, name: "foo">

1.9.3p392 :026 > c.cities.find_or_create_by(name: 'bar')
NoMethodError: undefined method `city' for nil:NilClass

So, it fails on a line "field :full_name, type: String, default: ->{ "#

, #

" }" becouse country is undefined for that moment