I have these models:
class User
include Mongoid::Document
has_one_related :account, :foreign_key => :creator_id
end

class Account
include Mongoid::Document
belongs_to_related :creator, :class_name => "User", :foreign_key => :creator_id, :inverse_of => :account
end

When I try to do @user.account.build, it tries to @account.user = @user, when it should call @account.creator = @user instead.

The culprit is in line 14-16 of mongoid/associations/has_one_related.rb

@target = @klass.instantiate(attributes)
name = @parent.class.to_s.underscore
@target.send("#

=", @parent)

It doesn't seem to respect the name of the belongs_to_related association.