модели
class Bigbluebutton::Room < ActiveRecord::Base
  self.table_name = 'bigbluebutton_rooms'

  has_many :user_vebinar
  has_many :users, through: :user_vebinar

  accepts_nested_attributes_for :users, allow_destroy: false, reject_if: :all_blank
end

class User < ActiveRecord::Base
    self.table_name = 'model_people'
    has_many :user_vebinar
    has_many :rooms, through: :user_vebinar
end

class UserVebinar < ActiveRecord::Base
    self.table_name = 'users_vebinars'

    validates_presence_of :user, :room
    belongs_to :user
    belongs_to :room
end


controller
class Bigbluebutton::RoomsController < ResourcesController

def create_students

        if params[:bigbluebutton_room].present? and params[:bigbluebutton_room][:users_attributes].present?
            params[:bigbluebutton_room][:users_attributes].slice!(*params[:bigbluebutton_room][:users_attributes].keys.slice(0, Bigbluebutton::Room::USERS_ENTER_AT_ONCE))

            params[:bigbluebutton_room][:users_attributes].each do |(k,v)|
                if v[:full_name].present?
                    names = (v[:full_name]+' - - -').split.slice(0,3)
                    found_user = User.accessible_by(current_ability).find_or_create_by(
                        :surname => names[0], :first_name => names[1], :middle_name => names[2]
                    )
                v[:id] = !found_user.new_record? ? found_user.id : {}
                end
            end
            update! do |success, failure|
                # success.html {
                #   if params[:save_and_continue].present?
                #       render :create_students, notice: 'Учащиеся добавлены.'
                #   else
                #       redirect_to resource, notice: 'Учащиеся добавлены.'
                #   end
                # }
                # success.js {
                #   if params[:save_and_continue].present?
                #       redirect_to url_for, notice: 'Учащиеся добавлены.'
                #   else
                #       flash[:notice] = 'Учащиеся добавлены.'
                #       flash.keep(:notice)
                #       render js: 'window.reload_page()', status: :ok
                #   end
                # }
            end
        end
    end
end