something unuseful

gistfile1.rb

# somewhere in controller

def update
  @group = Group.find(params[:id])
  if @group.update_with_user(params[:group], params[:user])
    redirect_to :index
  else
    render :edit
end

# somewhere in model
class Group < ActiveRecord::Base

def update_with_user group, user
  transaction do
    self.update_attributes(group)
    user = self.users.where(user) || self.users.build(user)
    user.update_attributes(user)
  end
end