公共活动中未定义的方法“销毁”

用户可以在屏幕上发表评论，并由 PublicActivity 进行跟踪：

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

注释取决于: :destroy 屏幕型号。

但是，当我删除屏幕时，虽然评论被删除，但该评论的 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

但删除屏幕后，我得到undefined methoddestroy' for nil:NilClass`。

我在 Railscast 上读到：

这是由于在对象创建后调用了create_activity方法 被摧毁了。

根据 gem 维护者的说法，你只需假设记录即可 会被销毁，并在销毁前调用create_activity

我缺少什么？

以下信息

屏幕.rb

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

评论.rb

belongs_to :user
belongs_to :screen

屏幕控制器.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

评论控制器.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

这就是我的屏幕控制器销毁操作现在的样子：

  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

又出现同样的错误：

这尚未经过测试，但我认为您应该这样做。

首先，您可以删除对 screen_controller#destroy 中活动的引用

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

应该在您对阻止的响应之外

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

让我知道这是否有效，但应该如此。