I would like update all object that was child of User

update all child one save

class User
  has_many :users_notes
  has_many :notes, :through => :users_notes
end

class UsersNote
  belongs_to :user
  bolongs_to :notes
end

class Note
  has_many :users_notes
  has_many :users , :through => :users_notes
end

My example 

user = User.new(:name=>"boo")
notes = []
notes <<  Note.new(:name=>"note1")
notes << note.new(:name => "note2")
user.notes = notes
user.save

/* result will two notes I suppose id of notes is 1,2  */


and then I will update User and Note as the same time.

user = User.find 1
user.name = "foo"

notes = []
note = Note.find 1
note.name = "noted 1"
notes << note

note2 = Note.find 2
note2.name = "noted 2"
notes << note2

user.notes = notes
user.save

but result wil not update 2 notes but user will be updated.

if will update 2 notes must remove relation table before for will update notes as same time