saucy/app/controllers/boards_controller.rb

class BoardsController < ApplicationController
  before_action :require_login

  def edit
    @users = User.where(active: true)
    @users += Array.new(6 - @users.size) { User.new }
  end

  def update
    User.update_board_members(board_params)

    redirect_to edit_board_path
  end

  private

  def board_params
    params.require('users')
  end
end