Postal邮件服务器代码中ApplicationController未定义logged_in?方法问题

我最近了解到Postal这款邮件服务器，对它免费开箱即用的功能很感兴趣。作为初级Rails开发者，我正在尝试对它做定制开发，已经完成部署且能正常运行，但遇到了一个问题：ApplicationController里频繁使用的logged_in?方法在代码库中找不到定义，也没找到提供该方法的Gem，不知道它是怎么加载的。相关代码如下：

require "authie/session"

class ApplicationController < ActionController::Base

  protect_from_forgery with: :exception

  before_action :login_required
  before_action :set_timezone

  rescue_from Authie::Session::InactiveSession, with: :auth_session_error
  rescue_from Authie::Session::ExpiredSession, with: :auth_session_error
  rescue_from Authie::Session::BrowserMismatch, with: :auth_session_error

  private

  def login_required
    return if logged_in?

    redirect_to login_path(return_to: request.fullpath)
  end

  def admin_required
    if logged_in?
      unless current_user.admin?
        render plain: "Not permitted"
      end
    else
      redirect_to login_path(return_to: request.fullpath)
    end
  end

  def require_organization_owner
    return if organization.owner == current_user

    redirect_to organization_root_path(organization), alert: "This page can only be accessed by the organization's owner (#{organization.owner.name})"
  end

  def auth_session_error(exception)
    Rails.logger.info "AuthSessionError: #{exception.class}: #{exception.message}"
    redirect_to login_path(return_to: request.fullpath)
  end

  def page_title
    @page_title ||= ["Postal"]
  end
  helper_method :page_title

  def redirect_to_with_return_to(url, *args)
    if params[:return_to].blank? || !params[:return_to].starts_with?("/")
      redirect_to url_with_return_to(url), *args
    else
      redirect_to url_with_return_to(url), *args
    end
  end

  def set_timezone
    Time.zone = logged_in? ? current_user.time_zone : "UTC"
  end

  def append_info_to_payload(payload)
    super
    payload[:ip] = request.ip
    payload[:user] = logged_in? ? current_user.id : nil
  end

  def url_with_return_to(url)
    if params[:return_to].blank? || !params[:return_to].starts_with?("/")
      url_for(url)
    else
      params[:return_to]
    end
  end

  def redirect_to_with_json(url, flash_messages = {})
    if url.is_a?(Array) && url[0] == :return_to
      url = url_with_return_to(url[1])
    else
      url = url_for(url)
    end

    flash_messages.each do |key, value|
      flash[key] = value
    end
    respond_to do |wants|
      wants.html { redirect_to url }
      wants.json { render json: { redirect_to: url } }
    end
  end

  def render_form_errors(action_name, object)
    respond_to do |wants|
      wants.html { render action_name }
      wants.json { render json: { form_errors: object.errors.full_messages }, status: :unprocessable_entity }
    end
  end

  def flash_now(type, message, options = {})
    respond_to do |wants|
      wants.html do
        flash.now[type] = message
        if options[:render_action]
          render options[:render_action]
        end
      end
      wants.json { render json: { flash: { type => message } } }
    end
  end

  def login(user)
    if logged_in?
      auth_session.invalidate!
      reset_session
    end
    Authie::Session.start(self, user: user)
    @current_user = user
  end

end

排查方向 #

• Authie Gem的内置辅助方法：代码中引入了authie/session，Authie默认会提供logged_in?这类辅助方法，通常是通过Authie::ControllerHelpers模块注入的。检查项目的初始化文件（如config/initializers/authie.rb）或ApplicationController的其他混入模块，看是否有include Authie::ControllerHelpers的代码。
• 项目自定义的Concern：Rails项目常用Concern复用认证逻辑，搜索项目中是否存在app/controllers/concerns/authentication.rb这类文件，里面可能定义了logged_in?和current_user，并被ApplicationController引入。
• 动态注入或全局扩展：搜索项目代码中的logged_in?字符串，排查是否通过define_method、include或extend在运行时动态添加了该方法，比如在lib目录的自定义扩展文件中。
• Postal源码结构参考：Postal作为开源项目，这类认证方法通常会放在app/controllers/concerns或lib/postal目录下，直接查看对应目录的文件即可找到定义。

临时适配方案 #

如果暂时找不到方法来源，可以在ApplicationController的private块中手动添加适配Authie逻辑的方法：

private

def logged_in?
  auth_session.present? && auth_session.active?
end

def current_user
  @current_user ||= auth_session&.user
end

def auth_session
  @auth_session ||= Authie::Session.get(self)
end

内容的提问来源于stack exchange，提问作者Mighty