Ruby on rails 未定义的局部变量或方法“new_comment”`

注释中的名称错误#创建

显示/评论/_form.html.erb 第#1行出现的位置：

未定义的局部变量或方法#

通知.rb

class Comment < ActiveRecord::Base
  after_save :create_notification #ERROR OCCURRED WHEN I INTRODUCED THIS LINE AND
  validates :activity, presence: true #THIS LINE
  validates :user, presence: true
  has_many :notifications
  belongs_to :commentable, polymorphic: true
  belongs_to :user
  belongs_to :activity

private

  def create_notification
    Notification.create(
      activity_id: self.activity_id, 
      user_id: self.user_id, 
      comment_id: self.id, 
      read: false
      )
  end
end

class Notification < ActiveRecord::Base
  belongs_to :activity
  belongs_to :comment
  belongs_to :user
end

class Activity < ActiveRecord::Base
  self.per_page = 20
  has_many :notifications
  belongs_to :user
  has_many :comments, as: :commentable
  belongs_to :trackable, polymorphic: true

  def conceal
    trackable.conceal
  end

  def page_number
    (index / per_page.to_f).ceil
  end

private

  def index
    Activity.order(created_at: :desc).index self
  end
end

resources :activities do
  resources :comments
  resources :notifications
  member do
    post :like
    post :notifications
  end
end

你知道原因是什么吗？这个错误来自于这里令人敬畏的答案：

谢谢

更新

class CommentsController

通知\u控制器

class NotificationsController < ApplicationController
    def index
    @notifications = current_user.notifications
    @notifications.each do |notification|
        notification.update_attribute(:read, true)
    end
    end


    def destroy
      @notification = Notification.find(params[:id])
      @notification.destroy
      redirect_to :back
    end
end

class ActivitiesController < ApplicationController
    def index
        @activities = Activity.order("created_at desc").paginate(:page => params[:page])
    end

    def show
          redirect_to(:back)
    end

  def like
    @activity = Activity.find(params[:id])
    @activity_like = current_user.activity_likes.build(activity: @activity)
    if @activity_like.save
      @activity.increment!(:likes)
      flash[:success] = 'Thanks for liking!'
    else
      flash[:error] = 'Two many likes'
    end  
      redirect_to(:back)
  end
end

类通知控制器

活动\u控制器

class NotificationsController < ApplicationController
    def index
    @notifications = current_user.notifications
    @notifications.each do |notification|
        notification.update_attribute(:read, true)
    end
    end


    def destroy
      @notification = Notification.find(params[:id])
      @notification.destroy
      redirect_to :back
    end
end

class ActivitiesController < ApplicationController
    def index
        @activities = Activity.order("created_at desc").paginate(:page => params[:page])
    end

    def show
          redirect_to(:back)
    end

  def like
    @activity = Activity.find(params[:id])
    @activity_like = current_user.activity_likes.build(activity: @activity)
    if @activity_like.save
      @activity.increment!(:likes)
      flash[:success] = 'Thanks for liking!'
    else
      flash[:error] = 'Two many likes'
    end  
      redirect_to(:back)
  end
end

类活动控制器params[：page]）
结束
def秀
将_重定向到（：返回）
结束
def-like
@activity=activity.find（参数[：id]）
@activity\u like=当前用户。activity\u like.build（activity:@activity）
如果@activity\u like.save
@活动。增量！（：喜欢）
flash[：success]=“谢谢喜欢！”
其他的
flash[：error]=“两个很多喜欢”
结束
将_重定向到（：返回）
结束
结束

应该是

而不是新注释，因为注释是数据库中的元素

谢谢Zippo！这给了我活动中的

namererror#索引定义的局部变量或该行的方法“comment”。它在实现我在comments.rb comments中提到的那两行之前就已经工作了。我从Joe的回答中得到了新的评论：@AnthonyGalli.com请发布你的控制器代码also@AnthonyGalli.com试试这个：
Nope@anusha，它给出了：
NoMethodError in Activities.#索引显示/comments/_form.html.erb，其中第1行出现：nil:NilClass的未定义方法“commentable”
@AnthonyGalli.com什么关于此