Ruby on rails 轨道ERB错误

我正在制作一个CRUD博客应用程序，并编写了以下代码：

<h1>New Article</h1>
<%= form_for :article , url:articles_path do|f| %>
  <% if @article.errors.any? %>
    <div id="error_explanation">
      <h2>
        <%= pluralize%>
      </h2>
    </div>
  <% end %>
    <p>
      <%= f.label :title %><br/>
      <%= f.text_field :title %>
    </p>
    <p>
      <%= f.label :text %><br/>
      <%= f.text_area :text %>
    </p>
    <p>
      <%= f.submit%>
    </p>
<% end %>
<%= link_to 'Back', articles_path %>

完整回溯如下：

app/views/articles/new.html.erb:5:in `block in _app_views_articles_new_html_erb___837982527363082027_69849494310700'
actionview (4.2.0) lib/action_view/helpers/capture_helper.rb:38:in `block in capture'
actionview (4.2.0) lib/action_view/helpers/capture_helper.rb:200:in `with_output_buffer'
actionview (4.2.0) lib/action_view/helpers/capture_helper.rb:38:in `capture'
actionview (4.2.0) lib/action_view/helpers/form_helper.rb:444:in `form_for'
app/views/articles/new.html.erb:3:in `_app_views_articles_new_html_erb___837982527363082027_69849494310700'
actionview (4.2.0) lib/action_view/template.rb:145:in `block in render'
activesupport (4.2.0) lib/active_support/notifications.rb:166:in `instrument'
actionview (4.2.0) lib/action_view/template.rb:333:in `instrument'
actionview (4.2.0) lib/action_view/template.rb:143:in `render'
actionview (4.2.0) lib/action_view/renderer/template_renderer.rb:54:in `block (2 levels) in render_template'
actionview (4.2.0) lib/action_view/renderer/abstract_renderer.rb:39:in `block in instrument'
activesupport (4.2.0) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.0) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.0) lib/active_support/notifications.rb:164:in `instrument'
actionview (4.2.0) lib/action_view/renderer/abstract_renderer.rb:39:in `instrument'
actionview (4.2.0) lib/action_view/renderer/template_renderer.rb:53:in `block in render_template'
actionview (4.2.0) lib/action_view/renderer/template_renderer.rb:61:in `render_with_layout'
actionview (4.2.0) lib/action_view/renderer/template_renderer.rb:52:in `render_template'
actionview (4.2.0) lib/action_view/renderer/template_renderer.rb:14:in `render'
actionview (4.2.0) lib/action_view/renderer/renderer.rb:42:in `render_template'
actionview (4.2.0) lib/action_view/renderer/renderer.rb:23:in `render'
actionview (4.2.0) lib/action_view/rendering.rb:100:in `_render_template'
actionpack (4.2.0) lib/action_controller/metal/streaming.rb:217:in `_render_template'
actionview (4.2.0) lib/action_view/rendering.rb:83:in `render_to_body'
actionpack (4.2.0) lib/action_controller/metal/rendering.rb:32:in `render_to_body'
actionpack (4.2.0) lib/action_controller/metal/renderers.rb:37:in `render_to_body'
actionpack (4.2.0) lib/abstract_controller/rendering.rb:25:in `render'
actionpack (4.2.0) lib/action_controller/metal/rendering.rb:16:in `render'
actionpack (4.2.0) lib/action_controller/metal/instrumentation.rb:41:in `block (2 levels) in render'
activesupport (4.2.0) lib/active_support/core_ext/benchmark.rb:12:in `block in ms'
/home/prio/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/benchmark.rb:303:in `realtime'
activesupport (4.2.0) lib/active_support/core_ext/benchmark.rb:12:in `ms'
actionpack (4.2.0) lib/action_controller/metal/instrumentation.rb:41:in `block in render'
actionpack (4.2.0) lib/action_controller/metal/instrumentation.rb:84:in `cleanup_view_runtime'
activerecord (4.2.0) lib/active_record/railties/controller_runtime.rb:25:in `cleanup_view_runtime'
actionpack (4.2.0) lib/action_controller/metal/instrumentation.rb:40:in `render'
actionpack (4.2.0) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (4.2.0) lib/action_controller/metal/implicit_render.rb:5:in `send_action'
actionpack (4.2.0) lib/abstract_controller/base.rb:198:in `process_action'
actionpack (4.2.0) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (4.2.0) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
activesupport (4.2.0) lib/active_support/callbacks.rb:117:in `call'
activesupport (4.2.0) lib/active_support/callbacks.rb:117:in `call'
activesupport (4.2.0) lib/active_support/callbacks.rb:234:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:234:in `call'
activesupport (4.2.0) lib/active_support/callbacks.rb:234:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0) lib/active_support/callbacks.rb:92:in `call'
activesupport (4.2.0) lib/active_support/callbacks.rb:92:in `_run_callbacks'
activesupport (4.2.0) lib/active_support/callbacks.rb:734:in `_run_process_action_callbacks'
activesupport (4.2.0) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.0) lib/abstract_controller/callbacks.rb:19:in `process_action'
actionpack (4.2.0) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (4.2.0) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
activesupport (4.2.0) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.0) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.0) lib/active_support/notifications.rb:164:in `instrument'
actionpack (4.2.0) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (4.2.0) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
activerecord (4.2.0) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (4.2.0) lib/abstract_controller/base.rb:137:in `process'
actionview (4.2.0) lib/action_view/rendering.rb:30:in `process'
actionpack (4.2.0) lib/action_controller/metal.rb:195:in `dispatch'
actionpack (4.2.0) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.2.0) lib/action_controller/metal.rb:236:in `block in action'
actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:73:in `call'
actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:42:in `serve'
actionpack (4.2.0) lib/action_dispatch/journey/router.rb:43:in `block in serve'
actionpack (4.2.0) lib/action_dispatch/journey/router.rb:30:in `each'
actionpack (4.2.0) lib/action_dispatch/journey/router.rb:30:in `serve'
actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:802:in `call'
rack (1.6.0) lib/rack/etag.rb:24:in `call'
rack (1.6.0) lib/rack/conditionalget.rb:25:in `call'
rack (1.6.0) lib/rack/head.rb:13:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/flash.rb:260:in `call'
rack (1.6.0) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.6.0) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/cookies.rb:560:in `call'
activerecord (4.2.0) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.2.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:647:in `call'
activerecord (4.2.0) lib/active_record/migration.rb:378:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.2.0) lib/active_support/callbacks.rb:88:in `call'
activesupport (4.2.0) lib/active_support/callbacks.rb:88:in `_run_callbacks'
activesupport (4.2.0) lib/active_support/callbacks.rb:734:in `_run_call_callbacks'
activesupport (4.2.0) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/reloader.rb:73:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/remote_ip.rb:78:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
web-console (2.1.1) lib/web_console/middleware.rb:37:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.2.0) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.2.0) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.2.0) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.2.0) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.6.0) lib/rack/methodoverride.rb:22:in `call'
rack (1.6.0) lib/rack/runtime.rb:18:in `call'
activesupport (4.2.0) lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
rack (1.6.0) lib/rack/lock.rb:17:in `call'
actionpack (4.2.0) lib/action_dispatch/middleware/static.rb:113:in `call'
rack (1.6.0) lib/rack/sendfile.rb:113:in `call'
railties (4.2.0) lib/rails/engine.rb:518:in `call'
railties (4.2.0) lib/rails/application.rb:164:in `call'
rack (1.6.0) lib/rack/lock.rb:17:in `call'
rack (1.6.0) lib/rack/content_length.rb:15:in `call'
rack (1.6.0) lib/rack/handler/webrick.rb:89:in `service'
/home/prio/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/webrick/httpserver.rb:138:in `service'
/home/prio/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/webrick/httpserver.rb:94:in `run'
/home/prio/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/webrick/server.rb:294:in `block in start_thread'

---

调用

new

时，变量

@article

未定义。表单中不需要该代码。你应该把这些代码放在你的节目里，或者你在创作完新文章后看到的任何视图中

编辑：如果保存失败，我看到您正在重定向回

new

。在这一点上，它将被定义。我将更改代码以检查是否首先定义了

@article

：

 <% if @article.errors %>

---

这将处理

@article

由于尚未调用而未定义的情况。

您需要定义“new”方法。这可能会起作用：

def新
@article=article.new
终止

---

你有两种“新”方法。擦除一个。

需要错误的完全回溯。您必须从控制器方法中传递

@article

，假设这是

new.html.erb

页面，那么在控制器中，您将在

@article=article.new

中拥有

new

方法。在

新方法中发布控制器代码只需添加
@article=article.new
 <% if @article.errors %>