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我在尝试实现 Hartl 的 Ruby on Rails 教程中的示例应用程序时遇到了一个奇怪的问题。

当我删除微博时，会发生以下情况：

  1. 微博被删除。
  2. 用户也被删除。
  3. 被定向到注册页面。

只有第一步应该发生。用户不应该被删除。当我删除微博时，控制台跟踪显示以下内容：

Started DELETE "/microposts/1" for 127.0.0.1 at 2013-07-23 11:35:31 -0400
Processing by MicropostsController#destroy as HTML
  Parameters: {"authenticity_token"=>"clfdQ1F/1ewiDnuae9OpVXSZ3S/wtieCrVYNM+Y1838=", "id"=>"1"}
  User Load (0.0ms)  SELECT "users".* FROM "users" WHERE "users"."remember_token" = 'cUs3NX6FrzU-XnkCbGE4wg' LIMIT 1
  Micropost Load (1.0ms)  SELECT "microposts".* FROM "microposts" WHERE "microposts"."user_id" = 1 AND "microposts"."id" = 1 ORDER BY microposts.created_at DESC LIMIT 1
   (0.0ms)  begin transaction
  SQL (2.0ms)  DELETE FROM "microposts" WHERE "microposts"."id" = ?  [["id", 1]]
  User Load (0.0ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
  SQL (1.0ms)  DELETE FROM "users" WHERE "users"."id" = ?  [["id", 1]]
   (12.0ms)  commit transaction
Redirected to http://localhost:3000/
Completed 302 Found in 27ms (ActiveRecord: 16.0ms)

我不确定为什么要发送 DELETE FROM "users"。

我的 application.js 文件如下所示：

//= require jquery
//= require jquery_ujs
//= require bootstrap
//= require_tree .

我的 routes.rb 看起来像这样：

SampleApp::Application.routes.draw do

  resources :users
  resources :sessions,    only: [:new, :create, :destroy]
  resources :microposts,  only: [:create, :destroy]

  root :to => 'static_pages#home'
  match '/signup',  to: 'users#new'
  match '/signin',  to: 'sessions#new'
  match '/signout', to: 'sessions#destroy', via: :delete
  match '/help',    to: 'static_pages#help'
  match '/about',   to: 'static_pages#about'
  match '/contact', to: 'static_pages#contact'
end

microposts_controller.rb 看起来像这样：

class MicropostsController < ApplicationController

  before_filter :signed_in_user, only: [:create, :destroy]
  before_filter :correct_user,   only: :destroy

  def create
    @micropost = current_user.microposts.build(params[:micropost])
    if @micropost.save
        flash[:success] = "Micropost created!"
        redirect_to root_path
    else
      @feed_items = []
        render 'static_pages/home'
    end
  end

  def destroy
    @micropost.destroy
    redirect_back_or root_path
  end

  private

   def correct_user
     @micropost = current_user.microposts.find_by_id(params[:id])
     redirect_to root_path if @micropost.nil?
   end
end

您可以在上面看到销毁操作是如何实现的（如教程中所述）。所以我不确定问题是什么。

这是 app/models/micropost.rb

class Micropost < ActiveRecord::Base
  # here we removed :user_id from attr_accessable for security reasons
  attr_accessible :content
  belongs_to :user, dependent: :destroy

  validates :content, presence: true, length: { maximum: 140 } 
  validates :user_id, presence: true

  default_scope order: 'microposts.created_at DESC'
end

感谢您对此的任何帮助。

4

2 回答 2

2

问题出在您的Micropost模型中。以下行正在删除与user关联的Micropost：

belongs_to :user, dependent: :destroy

将该行替换为：

belongs_to :user

并且您不会看到相关的用户被删除。

请在此处阅读有关“依赖关联”的文档：http: //api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html

更新：

如果你想删除属于某个用户的所有微博，那么你应该dependent: :destroy像User.rb下面这样添加：

has_many :microposts, dependent: :destroy
于 2013-07-23T16:15:52.713 回答
0

您的Micropost班级是说，当dependent: :destroy使用belongs_to :user.

从belongs_to 的文档中，:dependent 如果设置为 :destroy，则关联对象在该对象被销毁时被销毁。

因此，如果您删除它，dependent: :destroy您将不会遇到问题。

于 2013-07-23T16:16:29.173 回答