Question

我是RoR的新手。我正在尝试创建一个基本的Web应用程序，其中“配置文件”页面显示属于特定配置文件的项目列表。

到目前为止，我有：

rails generate scaffold Profile name:string
rails generate scaffold Item description:string
rake db:migrate

在个人资料模型中：has_many :items在项目模型中：belongs_to :profile

当我尝试创建新的个人资料时，我收到错误：

undefined method `item' for #<Profile

配置文件控制器

class ProfilesController < ApplicationController
  # GET /profiles
  # GET /profiles.json
  def index
    @profiles = profile.all

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @profiles }
    end
  end

  # GET /profiles/1
  # GET /profiles/1.json
  def show
    @profile = profile.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @profile }
    end
  end

  # GET /profiles/new
  # GET /profiles/new.json
  def new
    @profile = profile.new

    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @profile }
    end
  end

  # GET /profiles/1/edit
  def edit
    @profile = profile.find(params[:id])
  end

  # POST /profiles
  # POST /profiles.json
  def create
    @profile = profile.new(params[:profile])

    respond_to do |format|
      if @profile.save
        format.html { redirect_to @profile, notice: 'profile was successfully created.' }
        format.json { render json: @profile, status: :created, location: @profile }
      else
        format.html { render action: "new" }
        format.json { render json: @profile.errors, status: :unprocessable_entity }
      end
    end
  end

  # PUT /profiles/1
  # PUT /profiles/1.json
  def update
    @profile = profile.find(params[:id])

    respond_to do |format|
      if @profile.update_attributes(params[:profile])
        format.html { redirect_to @profile, notice: 'profile was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @profile.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /profiles/1
  # DELETE /profiles/1.json
  def destroy
    @profile = profile.find(params[:id])
    @profile.destroy

    respond_to do |format|
      format.html { redirect_to profiles_url }
      format.json { head :no_content }
    end
  end
end

个人资料index.html.erb

<h1>Listing profiles</h1>

<table>
  <tr>
    <th>Name</th>
    <th></th>
    <th></th>
    <th></th>
  </tr>

<% @profiles.each do |profile| %>
  <tr>
    <td><%= profile.name %></td>
    <td><%= link_to 'Show', profile %></td>
    <td><%= link_to 'Edit', edit_profile_path(profile) %></td>
    <td><%= link_to 'Destroy', profile, method: :delete, data: { confirm: 'Are you sure?' } %></td>
  </tr>
<% end %>
</table>

<br />

<%= link_to 'New profile', new_profile_path %>

个人资料_show.html.erb

<%= simple_form_for(@profile) do |f| %>
  <%= f.error_notification %>

  <div class="form-inputs">
    <%= f.input :name %>
  </div>

  <div class="form-inputs">
    <%= f.input :item %>
  </div>

  <div class="form-actions">
    <%= f.button :submit %>
  </div>
<% end %>

完整错误跟踪：

activemodel (3.2.12) lib/active_model/attribute_methods.rb:407:in `method_missing'
activerecord (3.2.12) lib/active_record/attribute_methods.rb:149:in `method_missing'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1161:in `value_before_type_cast'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1149:in `value_before_type_cast'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1043:in `block in to_input_field_tag'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1043:in `fetch'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1043:in `to_input_field_tag'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:692:in `text_field'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:1284:in `text_field'
simple_form (2.1.0) lib/simple_form/inputs/string_input.rb:13:in `input'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:29:in `block in render'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:27:in `each'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:27:in `render'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:29:in `block in render'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:27:in `each'
simple_form (2.1.0) lib/simple_form/wrappers/many.rb:27:in `render'
simple_form (2.1.0) lib/simple_form/wrappers/root.rb:15:in `render'
simple_form (2.1.0) lib/simple_form/form_builder.rb:117:in `input'
app/views/profiles/_form.html.erb:9:in `block in _app_views_profiles__form_html_erb___911765346923063960_2183588380'
actionpack (3.2.12) lib/action_view/helpers/capture_helper.rb:40:in `block in capture'
actionpack (3.2.12) lib/action_view/helpers/capture_helper.rb:187:in `with_output_buffer'
actionpack (3.2.12) lib/action_view/helpers/capture_helper.rb:40:in `capture'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:607:in `fields_for'
actionpack (3.2.12) lib/action_view/helpers/form_helper.rb:378:in `form_for'
simple_form (2.1.0) lib/simple_form/action_view_extensions/form_helper.rb:29:in `block in simple_form_for'
simple_form (2.1.0) lib/simple_form/action_view_extensions/form_helper.rb:48:in `with_simple_form_field_error_proc'
simple_form (2.1.0) lib/simple_form/action_view_extensions/form_helper.rb:28:in `simple_form_for'
app/views/profiles/_form.html.erb:1:in `_app_views_profiles__form_html_erb___911765346923063960_2183588380'
actionpack (3.2.12) lib/action_view/template.rb:145:in `block in render'
activesupport (3.2.12) lib/active_support/notifications.rb:125:in `instrument'
actionpack (3.2.12) lib/action_view/template.rb:143:in `render'
actionpack (3.2.12) lib/action_view/renderer/partial_renderer.rb:265:in `render_partial'
actionpack (3.2.12) lib/action_view/renderer/partial_renderer.rb:238:in `block in render'
actionpack (3.2.12) lib/action_view/renderer/abstract_renderer.rb:38:in `block in instrument'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.12) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.12) lib/action_view/renderer/abstract_renderer.rb:38:in `instrument'
actionpack (3.2.12) lib/action_view/renderer/partial_renderer.rb:237:in `render'
actionpack (3.2.12) lib/action_view/renderer/renderer.rb:41:in `render_partial'
actionpack (3.2.12) lib/action_view/helpers/rendering_helper.rb:27:in `render'
app/views/profiles/new.html.erb:3:in `_app_views_profiles_new_html_erb___3444063506780261827_2182112400'
actionpack (3.2.12) lib/action_view/template.rb:145:in `block in render'
activesupport (3.2.12) lib/active_support/notifications.rb:125:in `instrument'
actionpack (3.2.12) lib/action_view/template.rb:143:in `render'
actionpack (3.2.12) lib/action_view/renderer/template_renderer.rb:47:in `block (2 levels) in render_template'
actionpack (3.2.12) lib/action_view/renderer/abstract_renderer.rb:38:in `block in instrument'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.12) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.12) lib/action_view/renderer/abstract_renderer.rb:38:in `instrument'
actionpack (3.2.12) lib/action_view/renderer/template_renderer.rb:46:in `block in render_template'
actionpack (3.2.12) lib/action_view/renderer/template_renderer.rb:54:in `render_with_layout'
actionpack (3.2.12) lib/action_view/renderer/template_renderer.rb:45:in `render_template'
actionpack (3.2.12) lib/action_view/renderer/template_renderer.rb:18:in `render'
actionpack (3.2.12) lib/action_view/renderer/renderer.rb:36:in `render_template'
actionpack (3.2.12) lib/action_view/renderer/renderer.rb:17:in `render'
actionpack (3.2.12) lib/abstract_controller/rendering.rb:110:in `_render_template'
actionpack (3.2.12) lib/action_controller/metal/streaming.rb:225:in `_render_template'
actionpack (3.2.12) lib/abstract_controller/rendering.rb:103:in `render_to_body'
actionpack (3.2.12) lib/action_controller/metal/renderers.rb:28:in `render_to_body'
actionpack (3.2.12) lib/action_controller/metal/compatibility.rb:50:in `render_to_body'
actionpack (3.2.12) lib/abstract_controller/rendering.rb:88:in `render'
actionpack (3.2.12) lib/action_controller/metal/rendering.rb:16:in `render'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:40:in `block (2 levels) in render'
activesupport (3.2.12) lib/active_support/core_ext/benchmark.rb:5:in `block in ms'
/usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/benchmark.rb:295:in `realtime'
activesupport (3.2.12) lib/active_support/core_ext/benchmark.rb:5:in `ms'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:40:in `block in render'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:83:in `cleanup_view_runtime'
activerecord (3.2.12) lib/active_record/railties/controller_runtime.rb:24:in `cleanup_view_runtime'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:39:in `render'
actionpack (3.2.12) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (3.2.12) lib/action_controller/metal/mime_responds.rb:196:in `respond_to'
app/controllers/profiles_controller.rb:29:in `new'
actionpack (3.2.12) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (3.2.12) lib/abstract_controller/base.rb:167:in `process_action'
actionpack (3.2.12) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (3.2.12) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.2.12) lib/active_support/callbacks.rb:414:in `_run__312850119216024862__process_action__607287929354052739__callbacks'
activesupport (3.2.12) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.12) lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks'
activesupport (3.2.12) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.12) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.2.12) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.12) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.12) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.12) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.2.12) lib/action_controller/metal/params_wrapper.rb:207:in `process_action'
activerecord (3.2.12) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (3.2.12) lib/abstract_controller/base.rb:121:in `process'
actionpack (3.2.12) lib/abstract_controller/rendering.rb:45:in `process'
actionpack (3.2.12) lib/action_controller/metal.rb:203:in `dispatch'
actionpack (3.2.12) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.2.12) lib/action_controller/metal.rb:246:in `block in action'
actionpack (3.2.12) lib/action_dispatch/routing/route_set.rb:73:in `call'
actionpack (3.2.12) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
actionpack (3.2.12) lib/action_dispatch/routing/route_set.rb:36:in `call'
journey (1.0.4) lib/journey/router.rb:68:in `block in call'
journey (1.0.4) lib/journey/router.rb:56:in `each'
journey (1.0.4) lib/journey/router.rb:56:in `call'
actionpack (3.2.12) lib/action_dispatch/routing/route_set.rb:601:in `call'
warden (1.2.1) lib/warden/manager.rb:35:in `block in call'
warden (1.2.1) lib/warden/manager.rb:34:in `catch'
warden (1.2.1) lib/warden/manager.rb:34:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
rack (1.4.5) lib/rack/etag.rb:23:in `call'
rack (1.4.5) lib/rack/conditionalget.rb:25:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/head.rb:14:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/flash.rb:242:in `call'
rack (1.4.5) lib/rack/session/abstract/id.rb:210:in `context'
rack (1.4.5) lib/rack/session/abstract/id.rb:205:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/cookies.rb:341:in `call'
activerecord (3.2.12) lib/active_record/query_cache.rb:64:in `call'
activerecord (3.2.12) lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (3.2.12) lib/active_support/callbacks.rb:405:in `_run__1382692569756144731__call__1219384665416315194__callbacks'
activesupport (3.2.12) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.12) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
activesupport (3.2.12) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.12) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/reloader.rb:65:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
railties (3.2.12) lib/rails/rack/logger.rb:32:in `call_app'
railties (3.2.12) lib/rails/rack/logger.rb:16:in `block in call'
activesupport (3.2.12) lib/active_support/tagged_logging.rb:22:in `tagged'
railties (3.2.12) lib/rails/rack/logger.rb:16:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/request_id.rb:22:in `call'
rack (1.4.5) lib/rack/methodoverride.rb:21:in `call'
rack (1.4.5) lib/rack/runtime.rb:17:in `call'
activesupport (3.2.12) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.4.5) lib/rack/lock.rb:15:in `call'
actionpack (3.2.12) lib/action_dispatch/middleware/static.rb:62:in `call'
railties (3.2.12) lib/rails/engine.rb:479:in `call'
railties (3.2.12) lib/rails/application.rb:223:in `call'
rack (1.4.5) lib/rack/content_length.rb:14:in `call'
railties (3.2.12) lib/rails/rack/log_tailer.rb:17:in `call'
rack (1.4.5) lib/rack/handler/webrick.rb:59:in `service'
/usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
/usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
/usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'

Answer 1

要使has_many :items生效，您需要在profile_id:integer模型中使用Item。

您可以通过执行以下命令来完成

rails g migration add_profile_id_to_items profile_id:integer
rake db:migrate

这应该创建关联所需的外键。

之后你应该可以做这样的事情

@profile = Profile.create name: "MyProfile"
@item = @profile.items.build description: "This is my awesome item"
@item.save

为配置文件创建项目有不同的方法，但这是最直接的方式。然后检索这些项目你会做这样的事情

@profile = Profile.find(some_id)
@items = Item.where(profile_id: @profile.id).all

或

@profile = Profile.find(some_id)
@items = @profile.items

Answer 2

首先，您的个人资料对象没有＆＃39;项目＆＃39;领域。通过执行以下命令检查对象的属性：

rails console
Profile.connection
Profile

或访问您的db/schema.rb文件

您将看到对象散列中没有属性：item。

您可能希望在show.html.erb视图中显示个人资料的项目。首先，您需要创建它所属的配置文件的Item，如下所示：

item = Item.new(description: "Test description", profile_id: 1)

然后你可以这样做：

Profile.first.items

其次，您的控制器出错。对象的类应该大写，所以：

rails console
profile = profile.new(name: "Test profile")

会引发错误

undefined method `new' for nil:NilClass

简单的rails关联

2 个答案: