Rails 4 - Pundit - 如何编写范围

Question

我正在尝试学习如何将 Pundit 与 Rails 4 一起使用。过去 2 年我一直在尝试学习这一点，并且正在慢慢取得一点进展。

我也在尝试学习如何编写范围。我仍在试图弄清楚如何将建议翻译成简单的英语，以便我可以开始理解。

我陷入了权威政策使用的范围与我可以在模型中编写的一般范围类的交集。

我有 Uer、Profile 和 Project 的模型。

这些关联是：

用户

has_one :profile

简介

belongs_to :user
has_many :projects

项目

belongs_to :profile

我正在尝试编写一个权威政策，允许不同的用户查看不同的项目。我正在编写一个范围内的政策，权威人士来管理这个。

在我的项目模型中，我正在尝试编写可查找所有用户项目的范围。简单来说，我想在所有项目中搜索那些配置文件 id 属于等于当前用户的用户 id 的项目。

在我的权威政策中，我正在尝试编写此解决方法：

class Scope
    attr_reader :user, :scope

    def initialize(user, scope)
      @user  = user
      @scope = scope
    end

    def resolve
      if user.has_role?(:admin)
        scope.all
      elsif user.id == @project.profile.user_id
        scope.projects_for_user 
      elsif user.present?
        scope.in_state(:publish)
      else 
        Project.none  
      end
    end
  end

我已经尝试了大约 100 种不同的方法来尝试在我的项目模型上编写一个范围，以查找属于当前用户的项目。我知道我不能在模型中使用设计的 current_user，所以我不能在范围内使用它。这两个是我最好的尝试——都错了。

scope :projects_for_user, -> { joins(:user_id).where('project.profile.user_id = ?', user.id) }

scope :projects_for_user, -> { where(project.profile.user_id: User.id) }

我学习这个的主要问题是我看不出如何将这条线解构为不同的部分。

据我所知，“：”之前的位是您要查找的内容。 “：”之后的位是您在运行范围时使用的实例。如果这是正确的，那么我对为什么我的第二次尝试没有工作感到困惑（并且对第一次尝试中的 join 语句也很困惑）。

如果有人可以帮助用简单的英语解释如何编写范围，我相信我知道我想要寻找什么，只是拼命地迷失了如何编写查询来找到它。

目前，当我尝试使用我的项目政策时（我尝试在下面合并 Taryn 的建议 - 尽管我不了解范围的每个组成部分，所以我不确定它发生了什么）。

class ProjectPolicy < ApplicationPolicy

  attr_reader :user, :record

  class Scope
    attr_reader :user, :scope

    def initialize(user, scope)
      @user  = user
      @scope = scope
    end

    def resolve
      if user.has_role?(:admin)
        scope.all
      elsif user.id == @project.profile.user_id
        scope.projects_for_user(user)  
      elsif user.present?
        scope.in_state(:publish)
      else 
        Project.none  
      end
    end
  end


  def index?
    true
  end

  def show?
    true
  end

private
  def project
    record
  end

项目模型：

scope :projects_for_user, -> (user){ joins(:user_id).where('project.profile.user_id = ?', user.id) }

在我的项目控制器中，我有：

class ProjectsController < ApplicationController

  before_action :set_project, only: [:show, :edit, :update, :destroy ]
  before_action :authenticate_user!

  def index
    @projects = Project.all
    authorize @projects
  end

  def show
    @project = Project.find(params[:id])
    # authorize @project

  end

private
    def set_project
      @project = Project.find(params[:id])
      authorize @project
    end

当我保存并尝试它时，它会给出一个错误提示：

wrong number of arguments (given 2, expected 0)

当我尝试查看项目索引或特定项目时返回此错误（所以我认为这与范围无关）。我不明白哪两个论点被用来知道如何尝试解决这个问题。

添加堆栈跟踪

ArgumentError - wrong number of arguments (given 2, expected 0):
  pundit (1.1.0) lib/pundit.rb:112:in `policy!'
  pundit (1.1.0) lib/pundit.rb:235:in `policy'
  pundit (1.1.0) lib/pundit.rb:194:in `authorize'
  app/controllers/eois_controller.rb:20:in `show'
  actionpack (4.2.4) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
  actionpack (4.2.4) lib/abstract_controller/base.rb:198:in `process_action'
  actionpack (4.2.4) lib/action_controller/metal/rendering.rb:10:in `process_action'
  actionpack (4.2.4) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
  activesupport (4.2.4) lib/active_support/callbacks.rb:117:in `call'
  activesupport (4.2.4) lib/active_support/callbacks.rb:555:in `block (2 levels) in compile'
  activesupport (4.2.4) lib/active_support/callbacks.rb:505:in `call'
  activesupport (4.2.4) lib/active_support/callbacks.rb:92:in `__run_callbacks__'
  activesupport (4.2.4) lib/active_support/callbacks.rb:778:in `_run_process_action_callbacks'
  activesupport (4.2.4) lib/active_support/callbacks.rb:81:in `run_callbacks'
  actionpack (4.2.4) lib/abstract_controller/callbacks.rb:19:in `process_action'
  actionpack (4.2.4) lib/action_controller/metal/rescue.rb:29:in `process_action'
  actionpack (4.2.4) lib/action_controller/metal/instrumentation.rb:32:in `block in process_action'
  activesupport (4.2.4) lib/active_support/notifications.rb:164:in `block in instrument'
  activesupport (4.2.4) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
  activesupport (4.2.4) lib/active_support/notifications.rb:164:in `instrument'
  actionpack (4.2.4) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
  actionpack (4.2.4) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
  searchkick (1.3.0) lib/searchkick/logging.rb:153:in `process_action'
  activerecord (4.2.4) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
  actionpack (4.2.4) lib/abstract_controller/base.rb:137:in `process'
  actionview (4.2.4) lib/action_view/rendering.rb:30:in `process'
  actionpack (4.2.4) lib/action_controller/metal.rb:196:in `dispatch'
  actionpack (4.2.4) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
  actionpack (4.2.4) lib/action_controller/metal.rb:237:in `block in action'
  actionpack (4.2.4) lib/action_dispatch/routing/route_set.rb:76:in `dispatch'
  actionpack (4.2.4) lib/action_dispatch/routing/route_set.rb:45:in `serve'
  actionpack (4.2.4) lib/action_dispatch/journey/router.rb:43:in `block in serve'
  actionpack (4.2.4) lib/action_dispatch/journey/router.rb:30:in `serve'
  actionpack (4.2.4) lib/action_dispatch/routing/route_set.rb:821:in `call'
  omniauth (1.3.1) lib/omniauth/strategy.rb:186:in `call!'
  omniauth (1.3.1) lib/omniauth/strategy.rb:164:in `call'
  omniauth (1.3.1) lib/omniauth/strategy.rb:186:in `call!'
  omniauth (1.3.1) lib/omniauth/strategy.rb:164:in `call'
  omniauth (1.3.1) lib/omniauth/strategy.rb:186:in `call!'
  omniauth (1.3.1) lib/omniauth/strategy.rb:164:in `call'
  omniauth (1.3.1) lib/omniauth/strategy.rb:186:in `call!'
  omniauth (1.3.1) lib/omniauth/strategy.rb:164:in `call'
  meta_request (0.4.0) lib/meta_request/middlewares/app_request_handler.rb:13:in `call'
  meta_request (0.4.0) lib/meta_request/middlewares/meta_request_handler.rb:13:in `call'
  warden (1.2.6) lib/warden/manager.rb:35:in `block in call'
  warden (1.2.6) lib/warden/manager.rb:34:in `call'
  rack (1.6.4) lib/rack/etag.rb:24:in `call'
  rack (1.6.4) lib/rack/conditionalget.rb:25:in `call'
  rack (1.6.4) lib/rack/head.rb:13:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/flash.rb:260:in `call'
  rack (1.6.4) lib/rack/session/abstract/id.rb:225:in `context'
  rack (1.6.4) lib/rack/session/abstract/id.rb:220:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/cookies.rb:560:in `call'
  activerecord (4.2.4) lib/active_record/query_cache.rb:36:in `call'
  activerecord (4.2.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:653:in `call'
  activerecord (4.2.4) lib/active_record/migration.rb:377:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
  activesupport (4.2.4) lib/active_support/callbacks.rb:88:in `__run_callbacks__'
  activesupport (4.2.4) lib/active_support/callbacks.rb:778:in `_run_call_callbacks'
  activesupport (4.2.4) lib/active_support/callbacks.rb:81:in `run_callbacks'
  actionpack (4.2.4) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/reloader.rb:73:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/remote_ip.rb:78:in `call'
  better_errors (2.1.1) lib/better_errors/middleware.rb:84:in `protected_app_call'
  better_errors (2.1.1) lib/better_errors/middleware.rb:79:in `better_errors_call'
  better_errors (2.1.1) lib/better_errors/middleware.rb:57:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
  rack-contrib (1.4.0) lib/rack/contrib/response_headers.rb:17:in `call'
  meta_request (0.4.0) lib/meta_request/middlewares/headers.rb:16:in `call'
  web-console (2.3.0) lib/web_console/middleware.rb:28:in `block in call'
  web-console (2.3.0) lib/web_console/middleware.rb:18:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
  railties (4.2.4) lib/rails/rack/logger.rb:38:in `call_app'
  railties (4.2.4) lib/rails/rack/logger.rb:20:in `block in call'
  activesupport (4.2.4) lib/active_support/tagged_logging.rb:68:in `block in tagged'
  activesupport (4.2.4) lib/active_support/tagged_logging.rb:26:in `tagged'
  activesupport (4.2.4) lib/active_support/tagged_logging.rb:68:in `tagged'
  railties (4.2.4) lib/rails/rack/logger.rb:20:in `call'
  request_store (1.3.1) lib/request_store/middleware.rb:9:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/request_id.rb:21:in `call'
  rack (1.6.4) lib/rack/methodoverride.rb:22:in `call'
  rack (1.6.4) lib/rack/runtime.rb:18:in `call'
  activesupport (4.2.4) lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
  rack (1.6.4) lib/rack/lock.rb:17:in `call'
  actionpack (4.2.4) lib/action_dispatch/middleware/static.rb:116:in `call'
  rack (1.6.4) lib/rack/sendfile.rb:113:in `call'
  skylight (0.10.6) lib/skylight/middleware.rb:61:in `call'
  railties (4.2.4) lib/rails/engine.rb:518:in `call'
  railties (4.2.4) lib/rails/application.rb:165:in `call'
  rack (1.6.4) lib/rack/content_length.rb:15:in `call'
  puma (3.4.0) lib/puma/configuration.rb:224:in `call'
  puma (3.4.0) lib/puma/server.rb:569:in `handle_request'
  puma (3.4.0) lib/puma/server.rb:406:in `process_client'
  puma (3.4.0) lib/puma/server.rb:271:in `block in run'
  puma (3.4.0) lib/puma/thread_pool.rb:114:in `block in spawn_thread'

于 2016 年 9 月 8 日 13:23:01 +1000 开始为 ::1 发布“/__better_errors/123578515c1e4e10/variables”

堆栈跟踪分析

我自己写的唯一一行是 eois 控制器中的 authorize @eoi 行（在 show 操作内）。这是使用权威的关键部分。堆栈跟踪的其余部分来自我没有编写且不知道如何更改的内容。

 app/controllers/eois_controller.rb:20:in `show'

对可能的重复标签的响应

另一个问题也是我发布的。他们要去不同的地方。在这篇文章中，我想也许我写错了范围（我可能是）。在另一篇文章中，我试图列出整个过程，看看是否有人能够帮助我了解我哪里出错了。

Answer 1

问题是您实际上并没有为范围提供用户 ID。在这个：User.id 这永远不会工作...... User 类代表 所有 用户......询问它的 id 没有任何意义（你会只需取回存储类方法的 ruby​​-object 的 id）。

在另一个...你使用user.id，但实际上并没有设置user变量的值（所以它总是会失败）。

也许可以尝试将相关的用户 ID 作为参数传递给方法，例如：

# define the `user` parameter as an argument to this scope-method
scope :projects_for_user, -> (user){ joins(:user_id).where('project.profile.user_id = ?', user.id) }

def resolve
  if user.has_role?(:admin)
    scope.all
  elsif user.id == @project.profile.user_id
    scope.projects_for_user(user) # pass the user into the method
  elsif user.present?
    scope.in_state(:publish)
  else 
    Project.none  
  end
end

注意：我没有（也不会）测试此代码，它可能有拼写错误或错误...尝试并修复错误。