Ruby on rails 未定义的局部变量或“sign#u out'”方法；

当我点击“注销”链接时，即使该方法似乎存在，我也会出现以下错误

NameError in SessionsController#destroy 
undefined local variable or method `sign_out' for #<SessionsController:0x007f87c8ecd8d8>

布局

<header class="navbar navbar-fixed-top navbar-inverse">
  <div class="navbar-inner">
    <div class="container">
      <%= link_to "sample app", root_path, id: "logo" %>
      <nav>
        <ul class="nav pull-right">
          <li><%= link_to "Home", root_path %></li>
          <li><%= link_to "Help", help_path %></li>
          <% if signed_in? %>
            <li><%= link_to "Users", '#' %></li>
            <li id="fat-menu" class="dropdown">
              <a href="#" class="dropdown-toggle" data-toggle="dropdown">
                Account <b class="caret"></b>
              </a>
              <ul class="dropdown-menu">
                <li><%= link_to "Profile", current_user %></li>
                <li><%= link_to "Settings", '#' %></li>
                <li class="divider"></li>
                <li>
                  <%= link_to "Sign out", signout_path, method: "delete" %>
                </li>
              </ul>
            </li>
          <% else %>
            <li><%= link_to "Sign in", signin_path %></li>
          <% end %>
        </ul>
      </nav>
    </div>
  </div>
</header>

在会话控制器中包含会话帮助程序

class sessioncontroller

---

如果要使会话帮助器方法在所有控制器中都可用，请将其添加到应用程序控制器而不是会话控制器中。

I applogize，会话控制器中有一个小的输入错误。它现在起作用了

module SessionsHelper

  def sign_in(user)

    cookies.permanent[:remember_token] = user.remember_token
    self.current_user = user
  end

  def current_user=(user)
    @current_user = user
  end

  def current_user

    @current_user ||= User.find_by_remember_token(cookies[:remember_token])

  end

  def signed_in?
    !current_user.nil?
  end

   def sign_out
     self.current_user = nil
     cookies.delete(:remember_token)end
end

<header class="navbar navbar-fixed-top navbar-inverse">
  <div class="navbar-inner">
    <div class="container">
      <%= link_to "sample app", root_path, id: "logo" %>
      <nav>
        <ul class="nav pull-right">
          <li><%= link_to "Home", root_path %></li>
          <li><%= link_to "Help", help_path %></li>
          <% if signed_in? %>
            <li><%= link_to "Users", '#' %></li>
            <li id="fat-menu" class="dropdown">
              <a href="#" class="dropdown-toggle" data-toggle="dropdown">
                Account <b class="caret"></b>
              </a>
              <ul class="dropdown-menu">
                <li><%= link_to "Profile", current_user %></li>
                <li><%= link_to "Settings", '#' %></li>
                <li class="divider"></li>
                <li>
                  <%= link_to "Sign out", signout_path, method: "delete" %>
                </li>
              </ul>
            </li>
          <% else %>
            <li><%= link_to "Sign in", signin_path %></li>
          <% end %>
        </ul>
      </nav>
    </div>
  </div>
</header>