公共活动上的未定义方法`destroy’

用户可以在屏幕上发表评论,并由PublicActivity跟踪:

@comment.create_activity :create, owner: current_user, recipient: @comment.screen.user 

并且评论依赖于::在屏幕模型上销毁。

但是当我删除屏幕时,删除评论时,该评论的PublicActivity记录仍然存在。

这是我的Screens Controller

  def destroy @activity = PublicActivity::Activity.find_by_trackable_id(params[:id]) @activity.destroy #<-- Heres the Problem @screen.destroy respond_to do |format| format.html { redirect_to root_path } format.json { head :no_content } end end 

但是在删除屏幕时,我得到了undefined method destroy’for nil:NilClass`。

我在Railscast上读到:

它是由于在对象被销毁后调用create_activity方法。

根据gem维护者的说法,你只需假设记录将被销毁,并在销毁之前调用create_activity

我错过了什么?

以下信息

screen.rb

 belongs_to :user has_many :comments, :dependent => :destroy 

comment.rb

 belongs_to :user belongs_to :screen 

screens_contoller.rb

  def create @screen = current_user.screens.build(screen_params) respond_to do |format| if @screen.save format.html { redirect_to @screen, notice: 'You successfully uploaded your Screenshot.' } format.json { render action: 'show', status: :created, location: @screen } current_user.add_points(2, 'Points for Uploading a Screenshot') else format.html { render action: 'new' } format.json { render json: @screen.errors, status: :unprocessable_entity } end end end def destroy @activity = PublicActivity::Activity.find_by_trackable_id(params[:id]) @activity.destroy @screen.destroy respond_to do |format| format.html { redirect_to root_path } format.json { head :no_content } current_user.substract_points(1, "Substraction for Deleting a Screenshot") end end 

comments_controller.rb

  def create @screen = Screen.find(params[:screen_id]) @comment = current_user.comments.build(comment_params) @comment.screen_id = @screen.id respond_to do |format| if @comment.save # Create Record for Public Activity @comment.create_activity :create, owner: current_user, recipient: @comment.screen.user format.html { redirect_to @screen, notice: 'Comment was successfully created.' } format.json { render action: 'show', status: :created, location: @comment } else format.html { render action: 'new' } format.json { render json: @comment.errors, status: :unprocessable_entity } end end end def destroy @comment.destroy respond_to do |format| @activity = PublicActivity::Activity.find_by_trackable_id(params[:id]) @activity.destroy format.html { redirect_to :back } format.json { head :no_content } end end 

这就是我的Screen Controller Destroy Action现在的样子:

  def destroy @screen = current_user.screens.find(params[:id]) @activity = PublicActivity::Activity.find_by_trackable_id(params[:id]) @activity.destroy @screen.destroy current_user.substract_points(1, "Substraction for Deleting a Screenshot") respond_to do |format| format.html { redirect_to root_path } end end 

同样的错误:

在此处输入图像描述

这没有经过测试,但我认为你应该这样做。

首先,您可以删除screen_controller#destroy中对活动的引用

然后在你的comments_controller#destroy中

  @comment = current_user.comments.find(params[:id]) @activity = PublicActivity::Activity.find_by(trackable_id: (params[:id]), trackable_type: controller_path.classify) @activity.destroy @comment.destroy 

应该在你的回应之外阻止

接下来在您的评论模型中,您应该执行以下操作:

 #comment.rb private before_destroy :find_and_destroy_comments def find_and_destroy_comments activity = PublicActivity::Activity.find_by(trackable_id: self.id, trackable_type: self.class.name) if activity.present? activity.destroy end end 

调用before_destroy方法会覆盖在dependent: :destroy期间调用的默认ruby destroy方法

让我知道这是否有效,但它应该。