class Foo
  include Mongoid::Document
  field :foo, type: String
  embeds_many :bar
end

class Bar
  include Mongoid::Document
  field :bar, type: String
end

Foo.create!(foo: 'foo1', bar: [Bar.new(bar: 'bar1')])
doc = Foo.first
doc.bar = [Bar.new(bar: 'bar2')]
doc.foo = 'foo2'
p "-- After change"
p doc.foo
p doc.bar.first.bar
doc.reload
p "-- After reload"
p doc.foo
p doc.bar.first.bar
doc.save!
p "-- What's in the DB?"
p Foo.first.foo
p Foo.first.bar.first.bar