Rails问题与关系或部分

时间：2017-01-10 02:51:41

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

我正在尝试在rails中创建一个似乎导致一些问题的关系。我还将添加此问题似乎只出现在测试环境中，但问题是我们无法推送新代码失败。

我们有以下型号：

class User < ActiveRecord::Base
  has_many :enrolled_minors
end

次要

class Minor < ActiveRecord::Base
  has_many :enrolled_minors
end

注册未成年人

class EnrolledMinor < ActiveRecord::Base
  belongs_to :user
  belongs_to :minor
end

因此，用户有未成年人（未成年人），并且该关系通过已登记未成年人建模（也省略了更多信息）。以下是我创建注册小调的方法

@enrolled_minor = user.enrolled_minors.new(enrolled_minor_params)

def enrolled_minor_params
  params.require(:enrolled_minor).permit(:user_id, :minor_id)
end

索引视图的一部分

- if @user.enrolled_minors.count > 0 || current_user.is_admin
  - @user.enrolled_minors.each do |em|
    = puts "user info: #{@user.inspect}"
    = puts "em: #{em.inspect}"
    = puts "manual-minor: #{Minor.find(em.minor_id).inspect}"
    = puts "em-minor: #{em.minor.inspect}"
    .minor-container data-enrolled-minor-id=em.id
      .minor-overview
        .container
          = render partial: 'dashboard/overview', locals: {em: em}

部分显示故障（在h2线上失败）

- if em
  h2 #{em.minor.name}

来自put的输出

user info: #<User id: 2, first_name: "user3", last_name: "last_name3",  created_at: "2017-01-10 02:35:36", updated_at: "2017-01-10 02:35:36">
em: #<EnrolledMinor id: 1, minor_accepted: nil, minor_completed: nil, user_id: 2, created_at: "2017-01-10 02:35:37", updated_at: "2017-01-10 02:35:37", minor_id: 2>
manual-minor: #<Minor id: 2, name: "minor4", nickname: "m4">
em-minor: nil

堆栈跟踪

undefined method `name' for nil:NilClass (ActionView::Template::Error)
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  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_controller/metal/instrumentation.rb:43:in `render'
  /Users/ajk292/Documents/code/rails/dyson-minors/app/controllers/admin/users_controller.rb:13:in `show'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_controller/metal/implicit_render.rb:4:in `send_action'
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  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/abstract_controller/callbacks.rb:20:in `block in process_action'
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  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activesupport-4.2.4/lib/active_support/callbacks.rb:555:in `block (2 levels) in compile'
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  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activesupport-4.2.4/lib/active_support/callbacks.rb:505:in `call'
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  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_controller/metal/instrumentation.rb:32:in `block in process_action'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activesupport-4.2.4/lib/active_support/notifications.rb:164:in `block in instrument'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activesupport-4.2.4/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activesupport-4.2.4/lib/active_support/notifications.rb:164:in `instrument'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_controller/metal/instrumentation.rb:30:in `process_action'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activerecord-4.2.4/lib/active_record/railties/controller_runtime.rb:18:in `process_action'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/abstract_controller/base.rb:137:in `process'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionview-4.2.4/lib/action_view/rendering.rb:30:in `process'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_controller/metal.rb:196:in `dispatch'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_controller/metal.rb:237:in `block in action'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/routing/route_set.rb:76:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/routing/route_set.rb:76:in `dispatch'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/routing/route_set.rb:45:in `serve'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/journey/router.rb:43:in `block in serve'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/journey/router.rb:30:in `each'
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  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/middleware/flash.rb:260:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/session/abstract/id.rb:225:in `context'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/session/abstract/id.rb:220:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/middleware/cookies.rb:560:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activerecord-4.2.4/lib/active_record/query_cache.rb:36:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activerecord-4.2.4/lib/active_record/connection_adapters/abstract/connection_pool.rb:653:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activesupport-4.2.4/lib/active_support/callbacks.rb:88:in `__run_callbacks__'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activesupport-4.2.4/lib/active_support/callbacks.rb:778:in `_run_call_callbacks'
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  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/middleware/callbacks.rb:27:in `call'
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  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/cucumber-rails-1.4.2/lib/cucumber/rails/action_controller.rb:10:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/railties-4.2.4/lib/rails/rack/logger.rb:38:in `call_app'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/railties-4.2.4/lib/rails/rack/logger.rb:20:in `block in call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activesupport-4.2.4/lib/active_support/tagged_logging.rb:68:in `block in tagged'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activesupport-4.2.4/lib/active_support/tagged_logging.rb:26:in `tagged'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activesupport-4.2.4/lib/active_support/tagged_logging.rb:68:in `tagged'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/railties-4.2.4/lib/rails/rack/logger.rb:20:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/request_store-1.3.0/lib/request_store/middleware.rb:9:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/middleware/request_id.rb:21:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/methodoverride.rb:22:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/runtime.rb:18:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/activesupport-4.2.4/lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/lock.rb:17:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.4/lib/action_dispatch/middleware/static.rb:116:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/sendfile.rb:113:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/railties-4.2.4/lib/rails/engine.rb:518:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/railties-4.2.4/lib/rails/application.rb:165:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/urlmap.rb:66:in `block in call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/urlmap.rb:50:in `each'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/urlmap.rb:50:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/capybara-2.5.0/lib/capybara/server.rb:19:in `call'
  /Users/ajk292/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/handler/webrick.rb:88:in `service'
  /Users/ajk292/.rvm/rubies/ruby-2.2.3/lib/ruby/2.2.0/webrick/httpserver.rb:138:in `service'
  /Users/ajk292/.rvm/rubies/ruby-2.2.3/lib/ruby/2.2.0/webrick/httpserver.rb:94:in `run'
  /Users/ajk292/.rvm/rubies/ruby-2.2.3/lib/ruby/2.2.0/webrick/server.rb:294:in `block in start_thread'

所以我所做的就是我认为这个问题在某种程度上是未成年人与未成年人之间的关系。有一个参考，我可以＆＃34;手动＆＃34;通过使用find函数和存储的id找到它。另外正如我所说，这在运行测试时发生但在开发时没有。如果我在从Web开发服务器注册一个新的辅助页面后转到该页面，那么它就会成功。

有什么想法吗？

1 个答案:

答案 0 :(得分：0)

您希望在关联上指定：inverse_of选项，以确保不会将同一对象的不同版本加载到内存中。 

class User < ActiveRecord::Base
  has_many :enrolled_minors, inverse_of: :user
end

class Minor < ActiveRecord::Base
  has_many :enrolled_minors, inverse_of: :minor
end 

class EnrolledMinor < ActiveRecord::Base
  belongs_to :user, inverse_of: :enrolled_minors
  belongs_to :minor, inverse_of: :enrolled_minors
end

然后，当构建用户的enrolled_minor关联时，您可能不希望同时设置user_id参数，因为它会覆盖关联中的用户，所以

def user_built_enrolled_minor_params
  params.require(:enrolled_minor).permit(:minor_id)
end

然后

#build linked EnrolledMinor but don't save
@enrolled_minor = user.enrolled_minors.build(user_built_enrolled_minor_params)

#build linked EnrolledMinor and save
@enrolled_minor = user.enrolled_minors.create(user_built_enrolled_minor_params)
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