I am experimenting with Mongoid and embedded relations. I have a class A that can have three named 1..1 relations to class B, and I found it quite problematic to get the reverse relationship setup. After specifying class_name and inverse_of everything started working as expected.
class B
include Mongoid::Document
embedded_in :a, class_name: "A"
end
class A
include Mongoid::Document
embeds_one :something, class_name: "B", inverse_of: :a
embeds_one :completely class_name: "B", inverse_of: :a
embeds_one :different, class_name: "B", inverse_of: :a
end