I tried to use an embedded document with devise.
It seams somewhere "changed?" method is used.
My model as got this :
devise :database_authenticatable, :registerable, :rememberable, :trackable, :validatable
I think that the rememberable feature is responsible of the trouble. <= I just remove it and it works without
A quick console test showed me Embedded document do not have any "changed?" method, instead of Documents who get it.
I checkout the rememberable source, I can't catch where the missing func could be called. "changed?" is at least used in devise in rememberable_test.rb
I fixed the probleme adding a dirty def changed? false; end to my model but ... it's not really wise ...