想在管理系统里加一个管理员登陆和退出，用户名和密码写死，要用页面的方式登录，卡在表单提交后的数据该怎么接收？ app/views/users/index.html.erb如下：

<div class="form">
  <form action="/sign_in" class="simple_form">
    <h1>xxx<small>xxx</small></h1>
    <div class="input string optional placeholder">
      <label class="string optional" for="manager_username">名称</label>
      <input autofocus="autofocus" class="string optional" id="manager_username" maxlength="30" name="manager[username]" size="30" type="text" value="" placeholder="名称">
    </div>

    <div class="input password optional placeholder">
      <label class="password optional" for="manager_password">密码</label>
      <input class="password optional" id="manager_password" maxlength="128" name="manager[password]" size="30" type="password" placeholder="密码">
    </div>
    <div class="links">
      <div class="tr" style="text-align: left">
        <a href="#">注册用户</a>
      </div>
      <div class="tr" style="text-align: right">
        <a href="#">忘记密码?</a>
      </div>
    </div>

    <div class="form-action submit">
      <input type="submit" value="登录">
    </div>

    <div class="options">
      <input type="checkbox" id="login">
      <label for="login" class="auto_login">两周内自动登录</label>
    </div>
  </form>
</div>

routes.rb 如下

Rails.application.routes.draw do
  resources :users
  match '/sign_in',  to: 'users#sign_in', via: 'get'
end

users_controller.rb 如下

class UsersController < ApplicationController
  layout 'frontend_login_particle'

  def index

  end

  def sign_in

  end
end