nil的未定义方法`article'：NilClass

Question

我正在尝试在用户对文章发表评论时实施通知。我已经按照本教程https://gorails.com/episodes/in-app-navbar-notifications

进行了操作

但我不知道为什么文章和通知之间没有认可的关联。在rails控制台中复制并粘贴“Notification.first.notifiable.article”会产生结果。

错误讯息here

通知视图文件夹中的

index.json.jbuilder：

要求“json”

json.array! @notifications do |notification|
  json.id notification.id
  json.unread !notification.read_at?
  json.template render partial: "notifications/#{notification.notifiable_type.underscore.pluralize}/#{notification.action}", locals: {notification: notification}, formats: [:html]


end

更新

_posted.html.erb（代码行将呈现的部分内容： json.template渲染部分：“notifications /＃{notification.notifiable_type.underscore.pluralize} /＃{notification.action}”....）

<%= link_to article_path(notification.notifiable.article, anchor: dom_id(notification.notifiable)), class: "dropdown-item #{"unread" if !notification.read_at?}" do %>
  <%= notification.actor.name %>
  <%= notification.action %>
  a <%= notification.notifiable_type.underscore.humanize.downcase %>
<% end %>

通知控制器

class NotificationsController < ApplicationController
    def index 
        @notifications = Notification.where(recipient: current_user)
    end 

    def mark_as read 
      @notifications = Notification.where(recipient: current).unread 
      @notifications.update.all(read_at: Time.zone.now)
      render json: {success: true}
    end 
end

评论控制器

class CommentsController < ApplicationController
  before_action :authenticate_user!
  before_action :set_article
  before_action :set_comment, only: [:destroy, :edit, :update]

  def create
    @comment = @article.comments.new(comment_params)
    @comment.user = current_user
    respond_to do |format|
      if @comment.save
        Notification.create!(recipient: @article.user, actor: current_user, action: "posted", notifiable: @comment)
        redirect_to @article
      else
        redirect_to @article
      end
    end
  end

  private

    def set_article
      @article = Article.find(params[:article_id])
    end

    def set_comment
      @comment = @article.comments.find(params[:id])
    end

    def comment_params
      params.require(:comment).permit(:content)
    end
end