我试图学习如何使用Pails与Rails 4.我在过去的两年里一直在努力学习这一点，并且正在慢慢地取得一些进展。
我也在努力学习如何编写范围。我还在试图弄清楚如何将建议翻译成简单的英语，以便我能够开始理解。
我被困在范围专家政策使用的交叉点和我可以在模型中写的一般范围类。
我有Uer，Profile和Project的模型。
协会是：
用户
has_one :profile
资料
belongs_to :user
has_many :projects
项目
belongs_to :profile
我正在尝试编写一个权威策略，允许不同的用户查看不同的项目。我正在编写一份范围政策，专家来管理这个。
在我的项目模型中，我尝试编写查找所有用户项目的范围。用简单的英语，我想搜索所有项目，以查找那些属于用户ID等于当前用户的个人资料ID。
在我的专家政策中，我正在尝试编写这种解决方法：
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
我尝试了大约100种不同的尝试在我的项目模型上编写范围的方法，该范围可以找到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，所以我无法在范围内使用它。这两个是我最好的尝试 - 两者都错了。
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) }
我学习这个问题的主要问题是我无法看到如何将这条线解构为不同的部分。
从我能理解的那一点开始，＆＃34;：＆＃34;是你要找的东西。 ＆＃34;之后的位：＆＃34;是您在运行示波器时使用的实例。如果那是对的，那么我很困惑为什么我的第二次尝试没有工作（并且对第一次尝试中的连接声明也非常困惑）。
如果有人可以提供有关如何编写示波器的简单英语解释，我相信我知道我想要查找的内容，只是在如何编写查询以找到它时拼命丢失。
目前，当我尝试使用我的项目政策时（我已尝试在下面纳入Taryn的建议 - 虽然我不了解范围的每个组成部分，所以我不确定＆＃m？ 39;继续下去）。
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
当我保存并尝试时，会出现错误，其中包含：
wrong number of arguments (given 2, expected 0)
当我尝试查看项目或特定项目的索引时会返回此错误（因此我不认为它与范围有关）。我不明白为了解决这个问题，我们知道如何解决这两个问题。
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'
开始POST＆＃34; / __ better_errors / 123578515c1e4e10 / variables＆＃34; for :: 1 at 2016-09-08 13:23:01 +1000
分析痕迹
我自己编写的唯一一行是eois控制器中的授权@eoi行（在show动作中）。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写过的东西，也不知道如何改变。
app/controllers/eois_controller.rb:20:in `show'
回应可能的重复标记
另一个问题也是我发布的一个问题。他们会有不同的观点。在这篇文章中，我想也许我写的范围是错误的（我可能已经）。在另一篇文章中，我试图阐述整个过程，看看是否有人能够帮助我理解我哪里出错了。
答案 0 :(得分：0)
问题在于您实际上并没有为作用域提供用户ID。在这一个：User.id这将永远不会工作...... User类代表所有用户......要求它的ID是没有任何意义的（你只需要取回存储类方法的ruby-object的id。）
在另一个...中你使用user.id但实际上没有设置user变量的值（所以它总是会失败）。
也许尝试将相关的用户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...试一试并修复错误。