users_controller.rb

    @user.allotments.map &:destroy # delete old allotments

    # format: [ ['role', 'human-role', [1,2,3]], ['role', 'human-role', [1,2,3]] ] defined in user model.
    allots = []
    params[:roles_divisions].each do |rd|
      rd[2].each do |d|
        allots << Allotment.create(:user_id => @user.id, :division_id => d.to_i, :role_name => rd[0])
      end
    end