rails enum，根据条件加载枚举值是否可能？答案

【问题标题】：rails enum, load enum values based on condition is it possible?rails enum，根据条件加载枚举值是否可能？
【发布时间】：2016-09-13 05:28:15
【问题描述】：

可以说我有一个这样的枚举模型：

class Apt < ActiveRecord::Base
  enum apt_status: [ :draft, :publish, :unpublish, :waiting ]

end

在我的控制器中，我像这样加载我的枚举：

@apt_statuses = Apt.apt_statuses

它工作正常，但如果我想根据用户角色加载我的枚举值怎么办？所以假设我是管理员，我想加载我所有的枚举值，如果我不是管理员，我只显示 3 个枚举值

":draft, :unpublish, :waiting"

有可能吗？请建议。非常感谢。

顺便说一句，这是我的控制器，我真的不知道如何填充我的

@apt_statuses

在其他条件下

       ishaveprivilage = Usermaster.joins(:rolemasters, :rolemasters).where(id: @current_user.id, rolemasters: {name: "Super Admin"})


   if ishaveprivilage
        @apt_statuses = Apt.apt_statuses
   else

   end

我在这样的视图中使用我的枚举：

 <%= f.select :apt_status, options_for_select(@apt_statuses.collect { |s| [s[0].humanize, s[0]] }, selected: @apt.apt_status), {} , class: "form-control" %>

错误跟踪：

NoMethodError in Admin::Apts#new
Showing C:/Users/lenovo/Documents/urbanace/urbanacecode/app/views/admin/apts/_form.html.erb where line #134 raised:

undefined method `humanize' for :draft:Symbol
Trace of template inclusion: app/views/admin/apts/new.html.erb

Rails.root: C:/Users/lenovo/Documents/urbanace/urbanacecode

Application Trace | Framework Trace | Full Trace
app/views/admin/apts/_form.html.erb:134:in `block (2 levels) in _app_views_admin_apts__form_html_erb___8345113_90629556'
app/views/admin/apts/_form.html.erb:134:in `each'
app/views/admin/apts/_form.html.erb:134:in `collect'
app/views/admin/apts/_form.html.erb:134:in `block in _app_views_admin_apts__form_html_erb___8345113_90629556'
actionview (4.2.7) lib/action_view/helpers/capture_helper.rb:38:in `block in capture'
actionview (4.2.7) lib/action_view/helpers/capture_helper.rb:202:in `with_output_buffer'
actionview (4.2.7) lib/action_view/helpers/capture_helper.rb:38:in `capture'
actionview (4.2.7) lib/action_view/helpers/form_helper.rb:444:in `form_for'
app/views/admin/apts/_form.html.erb:57:in `_app_views_admin_apts__form_html_erb___8345113_90629556'
actionview (4.2.7) lib/action_view/template.rb:145:in `block in render'
activesupport (4.2.7) lib/active_support/notifications.rb:166:in `instrument'
actionview (4.2.7) lib/action_view/template.rb:333:in `instrument'
actionview (4.2.7) lib/action_view/template.rb:143:in `render'
actionview (4.2.7) lib/action_view/renderer/partial_renderer.rb:339:in `render_partial'
actionview (4.2.7) lib/action_view/renderer/partial_renderer.rb:310:in `block in render'
actionview (4.2.7) lib/action_view/renderer/abstract_renderer.rb:39:in `block in instrument'
activesupport (4.2.7) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.7) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.7) lib/active_support/notifications.rb:164:in `instrument'
actionview (4.2.7) lib/action_view/renderer/abstract_renderer.rb:39:in `instrument'
actionview (4.2.7) lib/action_view/renderer/partial_renderer.rb:309:in `render'
actionview (4.2.7) lib/action_view/renderer/renderer.rb:51:in `render_partial'
actionview (4.2.7) lib/action_view/helpers/rendering_helper.rb:35:in `render'
app/views/admin/apts/new.html.erb:2:in `_app_views_admin_apts_new_html_erb__809278863_96977256'
actionview (4.2.7) lib/action_view/template.rb:145:in `block in render'
activesupport (4.2.7) lib/active_support/notifications.rb:166:in `instrument'
actionview (4.2.7) lib/action_view/template.rb:333:in `instrument'
actionview (4.2.7) lib/action_view/template.rb:143:in `render'
actionview (4.2.7) lib/action_view/renderer/template_renderer.rb:54:in `block (2 levels) in render_template'
actionview (4.2.7) lib/action_view/renderer/abstract_renderer.rb:39:in `block in instrument'
activesupport (4.2.7) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.7) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.7) lib/active_support/notifications.rb:164:in `instrument'
actionview (4.2.7) lib/action_view/renderer/abstract_renderer.rb:39:in `instrument'
actionview (4.2.7) lib/action_view/renderer/template_renderer.rb:53:in `block in render_template'
actionview (4.2.7) lib/action_view/renderer/template_renderer.rb:61:in `render_with_layout'
actionview (4.2.7) lib/action_view/renderer/template_renderer.rb:52:in `render_template'
actionview (4.2.7) lib/action_view/renderer/template_renderer.rb:14:in `render'
actionview (4.2.7) lib/action_view/renderer/renderer.rb:46:in `render_template'
actionview (4.2.7) lib/action_view/renderer/renderer.rb:27:in `render'
actionview (4.2.7) lib/action_view/rendering.rb:100:in `_render_template'
actionpack (4.2.7) lib/action_controller/metal/streaming.rb:217:in `_render_template'
actionview (4.2.7) lib/action_view/rendering.rb:83:in `render_to_body'
actionpack (4.2.7) lib/action_controller/metal/rendering.rb:32:in `render_to_body'
actionpack (4.2.7) lib/action_controller/metal/renderers.rb:37:in `render_to_body'
actionpack (4.2.7) lib/abstract_controller/rendering.rb:25:in `render'
actionpack (4.2.7) lib/action_controller/metal/rendering.rb:16:in `render'
actionpack (4.2.7) lib/action_controller/metal/instrumentation.rb:44:in `block (2 levels) in render'
activesupport (4.2.7) lib/active_support/core_ext/benchmark.rb:12:in `block in ms'
C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/benchmark.rb:303:in `realtime'
activesupport (4.2.7) lib/active_support/core_ext/benchmark.rb:12:in `ms'
actionpack (4.2.7) lib/action_controller/metal/instrumentation.rb:44:in `block in render'
actionpack (4.2.7) lib/action_controller/metal/instrumentation.rb:87:in `cleanup_view_runtime'
activerecord (4.2.7) lib/active_record/railties/controller_runtime.rb:25:in `cleanup_view_runtime'
actionpack (4.2.7) lib/action_controller/metal/instrumentation.rb:43:in `render'
remotipart (1.2.1) lib/remotipart/render_overrides.rb:14:in `render_with_remotipart'
actionpack (4.2.7) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (4.2.7) lib/action_controller/metal/implicit_render.rb:5:in `send_action'
actionpack (4.2.7) lib/abstract_controller/base.rb:198:in `process_action'
actionpack (4.2.7) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (4.2.7) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
activesupport (4.2.7) lib/active_support/callbacks.rb:117:in `call'
activesupport (4.2.7) lib/active_support/callbacks.rb:117:in `call'
activesupport (4.2.7) lib/active_support/callbacks.rb:555:in `block (2 levels) in compile'
activesupport (4.2.7) lib/active_support/callbacks.rb:505:in `call'
activesupport (4.2.7) lib/active_support/callbacks.rb:505:in `call'
activesupport (4.2.7) lib/active_support/callbacks.rb:92:in `__run_callbacks__'
activesupport (4.2.7) lib/active_support/callbacks.rb:778:in `_run_process_action_callbacks'
activesupport (4.2.7) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.7) lib/abstract_controller/callbacks.rb:19:in `process_action'
actionpack (4.2.7) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (4.2.7) lib/action_controller/metal/instrumentation.rb:32:in `block in process_action'
activesupport (4.2.7) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.7) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.7) lib/active_support/notifications.rb:164:in `instrument'
actionpack (4.2.7) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (4.2.7) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
activerecord (4.2.7) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (4.2.7) lib/abstract_controller/base.rb:137:in `process'
actionview (4.2.7) lib/action_view/rendering.rb:30:in `process'
actionpack (4.2.7) lib/action_controller/metal.rb:196:in `dispatch'
actionpack (4.2.7) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.2.7) lib/action_controller/metal.rb:237:in `block in action'
actionpack (4.2.7) lib/action_dispatch/routing/route_set.rb:74:in `call'
actionpack (4.2.7) lib/action_dispatch/routing/route_set.rb:74:in `dispatch'
actionpack (4.2.7) lib/action_dispatch/routing/route_set.rb:43:in `serve'
actionpack (4.2.7) lib/action_dispatch/journey/router.rb:43:in `block in serve'
actionpack (4.2.7) lib/action_dispatch/journey/router.rb:30:in `each'
actionpack (4.2.7) lib/action_dispatch/journey/router.rb:30:in `serve'
actionpack (4.2.7) lib/action_dispatch/routing/route_set.rb:817: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'
remotipart (1.2.1) lib/remotipart/middleware.rb:27:in `call'
actionpack (4.2.7) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.2.7) 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 (4.2.7) lib/action_dispatch/middleware/cookies.rb:560:in `call'
activerecord (4.2.7) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.2.7) lib/active_record/connection_adapters/abstract/connection_pool.rb:653:in `call'
activerecord (4.2.7) lib/active_record/migration.rb:377:in `call'
actionpack (4.2.7) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.2.7) lib/active_support/callbacks.rb:88:in `__run_callbacks__'
activesupport (4.2.7) lib/active_support/callbacks.rb:778:in `_run_call_callbacks'
activesupport (4.2.7) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.7) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.2.7) lib/action_dispatch/middleware/reloader.rb:73:in `call'
actionpack (4.2.7) lib/action_dispatch/middleware/remote_ip.rb:78:in `call'
actionpack (4.2.7) lib/action_dispatch/middleware/debug_exceptions.rb:17: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 `catch'
web-console (2.3.0) lib/web_console/middleware.rb:18:in `call'
actionpack (4.2.7) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.2.7) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.2.7) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.2.7) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.2.7) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.2.7) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.2.7) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.2.7) 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 (4.2.7) lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
rack (1.6.4) lib/rack/lock.rb:17:in `call'
actionpack (4.2.7) lib/action_dispatch/middleware/static.rb:120:in `call'
rack (1.6.4) lib/rack/sendfile.rb:113:in `call'
railties (4.2.7) lib/rails/engine.rb:518:in `call'
railties (4.2.7) lib/rails/application.rb:165:in `call'
rack (1.6.4) lib/rack/lock.rb:17:in `call'
rack (1.6.4) lib/rack/content_length.rb:15:in `call'
rack (1.6.4) lib/rack/handler/webrick.rb:88:in `service'
C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/webrick/httpserver.rb:138:in `service'
C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/webrick/httpserver.rb:94:in `run'
C:/RailsInstaller/Ruby2.2.0/lib/ruby/2.2.0/webrick/server.rb:294:in `block in start_thread'
Request

Parameters:

None
Toggle session dump
_csrf_token: "DK6t1OuVBdMWZLihVgktZFIQSo7gX3qt5Iq5ZHyA7lM="
session_id: "2391dc6faaafcd52ee1815ccbe115daf"
user_id: 7
Toggle env dump
GATEWAY_INTERFACE: "CGI/1.1"
HTTP_ACCEPT: "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8"
HTTP_ACCEPT_ENCODING: "gzip, deflate, sdch"
HTTP_ACCEPT_LANGUAGE: "en-US,en;q=0.8"
HTTP_CACHE_CONTROL: "max-age=0"
REMOTE_ADDR: "127.0.0.1"
REMOTE_HOST: "127.0.0.1"
SERVER_NAME: "localhost"
SERVER_PROTOCOL: "HTTP/1.1"
Response

Headers:

None
x
>>

【问题讨论】：

标签： ruby-on-rails ruby-on-rails-3 ruby-on-rails-4 rails-activerecord

【解决方案1】：

我想我会这样解决这个问题：

class Apt < ActiveRecord::Base
  enum status: [:draft, :publish, :unpublish, :waiting]

  def self.user_specific_statuses(user)
    if user.admin? # define a method in your user model which defines this.
      Apt.statuses
    else
      Apt.statuses.reject { |k, v| k == "publish" } # => all except publish
    end
  end
end

然后你可以这样称呼它：

Apt.user_specific_statuses(admin_user) # => all statuses
Apt.user_specific_statuses(normal_user) # => only draft, unpublish, waiting

【讨论】：

你好，谢谢你的建议，我有一个问题想，我从这个api.rubyonrails.org/classes/ActiveRecord/Enum.html读到说如果我使用2个具有相同值的枚举，在我的情况下：“草稿，取消发布，等待" 必须使用前缀的东西吗？顺便说一句，我还为我的情况想出了一个解决方法，这是一种更好的方法。
我尝试了你的建议，导致视图出现错误，未定义的方法 `humanize' for :draft:Symbol
您能否将堆栈跟踪添加到您的问题中？
用视图使用和错误跟踪更新了我的问题
它起作用了，“拒绝”可以解决问题，但我想这与我的答案几乎相同，唯一不同的是我的方法发生在控制器中，而你的方法发生在模型中，即在我想多次使用这个模型的情况下更有效。赞成。谢谢。

【解决方案2】：

我不知道这是不是一个理想的方法，但我用这种方法解决了它：

我将我的模型枚举定义更改为：

型号：enum apt_status: { draft:0, publish:1, unpublish:2, waiting:3 }

在我的控制器中我这样做了：

 ishaveprivilage = Usermaster.joins(:rolemasters, :rolemasters).where(id: @current_user.id, rolemasters: {name: "Super Admin"})

          if !ishaveprivilage.blank?    

                @apt_statuses = Apt.apt_statuses
          else
                temp = Apt.apt_statuses.reject { |k,v| v == 1 } #remove Publish option for non super admin
                @apt_statuses = temp
          end

如果你们有更好的方法，请指教。

【讨论】：