ruby-on-rails - AbstractController::DoubleRenderError cannot be fixed with “redirect_to and return”

Question

今天，当我尝试为用户 Controller 使用一些辅助方法时，出现了此错误:

AbstractController::DoubleRenderError (Render and/or redirect were called multiple times in this action. Please note that you may only call render OR redirect, and at most once per action. Also note that neither redirect nor render terminate execution of the action, so if you want to exit an action after redirecting, you need to do something like "redirect_to(...) and return".)

我把以下助手放在 application_controller.rb中:

class ApplicationController < ActionController::Base

    def current_user
      User.find_by :id=>session[:user_id]
    end

    def log_in?
      !!session[:user_id]
    end

    def log_in_first
        if !log_in?
          session[:error]="You have to log in first to continue your operation"
          redirect_to("/login") and return
        end
      end

      def correct_user?
        if !(current_user.id.to_s==params[:id])
          session[:error]="You have no right to do this operation."
          redirect_to "/"
          return
        end
      end
end

这是 user_controller.rb:

class UsersController < ApplicationController

    def new
        @user = User.new
    end

    def create
        @user = User.new(user_params)
        if @user.save
          session[:user_id]=@user.id
          redirect_to user_path(@user)
        else
          render 'new'
        end
    end

    def show
        log_in_first
        @user = User.find_by id: params[:id]
        correct_user?
        if @user
            render 'show'
        else
            redirect_to '/login'
        end
    end



    private
      def user_params
        params.require(:user).permit(:name,:password,:email,:email_confirmation)
      end
end

如您所见，我尝试在 return和 and return中同时使用 log_in_first和 correct_user?来解决此问题，但仍然无法正常工作。有人有什么想法吗？

Answer 1

问题出在show Action 中，log_in_first重定向，然后show Action 执行所需的操作，即重定向或渲染。这导致错误。

更好的解决方案是使用before_action进行身份验证和授权，并仅让用户 Controller 操作执行其任务。如下所示。

  class ApplicationController < ActionController::Base

    def current_user
      User.find_by :id=>session[:user_id]
    end

    def log_in?
      !!session[:user_id]
    end

    def authenticate_user!
      if !log_in?
        session[:error]="You have to log in first to continue your operation"
        redirect_to("/login")
      end
    end

     def authorize_user!
       unless current_user&.id.to_s==params[:id]
         session[:error]="You have no right to do this operation."
         redirect_to "/"
       end
     end
  end

class UsersController < ApplicationController
  before_action :authenticate_user!, only: [:show]
  before_action :authorize_user!, only: [:show]

    def new
        @user = User.new
    end

    def create
        @user = User.new(user_params)
        if @user.save
          session[:user_id]=@user.id
          redirect_to user_path(@user)
        else
          render 'new'
        end
    end

    def show
      @user = User.find_by id: params[:id]
      render 'show'
    end

    private
      def user_params
        params.require(:user).permit(:name,:password,:email,:email_confirmation)
      end
end