回答您的具体问题：

Question

Quantifieds #index

中的NoMethodError

#Quantified的未定义方法`date_value'：0x007ff3fe7d6c08

如何定义date_value＆amp; result_value所以它在quantieds索引中有效吗？

<!-- Default bootstrap panel contents -->

<div id="values" class="panel panel-default">
  
  <div class="panel-heading"><h4><b>AVERAGE</b></h4></div>

  <!-- Table -->
<table>
  <% @averaged_quantifieds.each do |averaged| %>
    <% if averaged.user == current_user %>
        <th class="value">
          <%= link_to edit_quantified_path(averaged) do %>
          <%= averaged.name %>
          <% end %>
          (<%= averaged.metric %>)
        </th>
      <tbody class="value"> 
          <td><%= averaged.date_value.strftime("%m-%Y") %></td>
          <td><%= averaged.result_value %></td>
      </tbody>
    <% end %>
  <% end %>
</table>
</div>

<br>
<br>
<br>
<br>

<!-- Default bootstrap panel contents -->
<div id="values" class="panel panel-default">
  
  <div class="panel-heading"><h4><b>INSTANCE</b></h4></div>

  <!-- Table -->
<table>
  <% @instance_quantifieds.each do |instance| %>
    <% if instance.user == current_user %>
        <th class="value">
          <%= link_to edit_quantified_path(instance) do %>
          <%= instance.name %>
          <% end %>
          (<%= instance.metric %>)
        </th>
      <tbody class="value"> 
          <td><%= instance.date_value.strftime("%m-%Y") %></td>
          <td><%= instance.result_value %></td>
      </tbody>
    <% end %>
    <% end %>
</table>
</div>

  <div class="values-button">
  <%= link_to new_quantified_path, class: 'btn'  do %>
  <b><span class="glyphicon glyphicon-plus"</span></b>
  <% end %>
  </div>

date_value＆amp; result_value派生自f.simple_fields_for：结果为_form。我正在使用cocoon来创建我的嵌套属性。

= simple_form_for @quantified do |f|
  .america
    %form
      = f.select :categories, Quantified::CATEGORIES
      %br/
      %br/
      .form-group
        = f.text_field :name,  class: 'form-control', placeholder: 'Enter Name'
      .form-group
        = f.text_field :metric,  class: 'form-control', placeholder: 'Enter Metric'
      #results
        = f.simple_fields_for :results do |result|
          = render 'result_fields', :f => result
        = link_to_add_association 'Add Result', f, :results
      %br/
      = button_tag(type: 'f.submit', class: "btn") do
        %span.glyphicon.glyphicon-plus

.nested-fields
 .form-group
  = f.text_field :result_value, class: 'form-control', placeholder: 'Enter Result'
  %br
  = f.date_select :date_value, :order => [:month, :year], class: 'date-select'
  = link_to_remove_association "Remove Result", f

我认为可以在改变控制器时找到解决方案：

class QuantifiedsController < ApplicationController
  before_action :set_quantified, only: [:show, :edit, :update, :destroy]
  before_action :authenticate_user!, except: [:index, :show]

  def index
   @quantified = Result.all.order("date_value")
   @averaged_quantifieds = current_user.quantifieds.averaged
   @instance_quantifieds = current_user.quantifieds.instance
  end

  def show
  end

  def new
    @quantified = current_user.quantifieds.build
    @quantified.results.build
  end

  def edit
  end

  def create
    @quantified = current_user.quantifieds.build(quantified_params)
    if @quantified.save
      redirect_to quantifieds_url, notice: 'Quantified was successfully created'
    else
      render action: 'new'
  end
end

  def update
    if @quantified.update(quantified_params)
      redirect_to quantifieds_url, notice: 'Goal was successfully updated'
    else
      render action: 'edit'
  end
end

  def destroy
    @quantified.destroy
    redirect_to quantifieds_url
  end

  private
    def set_quantified
      @quantified = Quantified.find(params[:id])
    end

    def correct_user
      @quantified = current_user.quantifieds.find_by(id: params[:id])
      redirect_to quantifieds_path, notice: "Not authorized to edit this goal" if @quantified.nil?
    end

    def quantified_params
      params.require(:quantified).permit(:categories, :name, :metric, :result, :date, results_attributes: [:id, :result_value, :date_value, :_destroy])
    end
end

这里有一些代码可以提供更多上下文：

的routes.rb

Rails.application.routes.draw do

  resources :goals

  resources :values

  resources :quantifieds do
    resources :results
  end
  devise_for :users
  root 'values#index'
  get "about" => "pages#about"

schema.rb

# encoding: UTF-8
# This file is auto-generated from the current state of the database. Instead
# of editing this file, please use the migrations feature of Active Record to
# incrementally modify your database, and then regenerate this schema definition.
#
# Note that this schema.rb definition is the authoritative source for your
# database schema. If you need to create the application database on another
# system, you should be using db:schema:load, not running all the migrations
# from scratch. The latter is a flawed and unsustainable approach (the more migrations
# you'll amass, the slower it'll run and the greater likelihood for issues).
#
# It's strongly recommended that you check this file into your version control system.

ActiveRecord::Schema.define(version: 20150123210404) do

  create_table "goals", force: true do |t|
    t.string   "name"
    t.date     "deadline"
    t.boolean  "accomplished", default: false
    t.datetime "created_at",                   null: false
    t.datetime "updated_at",                   null: false
    t.integer  "user_id"
  end

  add_index "goals", ["deadline"], name: "index_goals_on_deadline"
  add_index "goals", ["user_id"], name: "index_goals_on_user_id"

  create_table "quantifieds", force: true do |t|
    t.string   "categories"
    t.string   "name"
    t.string   "metric"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.integer  "user_id"
  end

  add_index "quantifieds", ["categories"], name: "index_quantifieds_on_categories"
  add_index "quantifieds", ["user_id"], name: "index_quantifieds_on_user_id"

  create_table "results", force: true do |t|
    t.string   "result_value"
    t.date     "date_value"
    t.integer  "quantified_id"
    t.datetime "created_at",    null: false
    t.datetime "updated_at",    null: false
    t.integer  "user_id"
  end

  add_index "results", ["quantified_id"], name: "index_results_on_quantified_id"
  add_index "results", ["user_id"], name: "index_results_on_user_id"

  create_table "users", force: true do |t|
    t.string   "email",                  default: "", null: false
    t.string   "encrypted_password",     default: "", null: false
    t.string   "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          default: 0,  null: false
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.string   "current_sign_in_ip"
    t.string   "last_sign_in_ip"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "name"
  end

  add_index "users", ["email"], name: "index_users_on_email", unique: true
  add_index "users", ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true

  create_table "values", force: true do |t|
    t.string   "name"
    t.string   "categories"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.integer  "user_id"
  end

  add_index "values", ["categories"], name: "index_values_on_categories"
  add_index "values", ["user_id"], name: "index_values_on_user_id"

end

_create_results.rb

class CreateResults < ActiveRecord::Migration
  def change
    create_table :results do |t|
      t.string :result_value
      t.date :date_value
      t.belongs_to :quantified, index: true

      t.timestamps null: false
    end
    add_foreign_key :results, :quantifieds
  end
end

_add_user_id_to_results.rb

class AddUserIdToResults < ActiveRecord::Migration
  def change
    add_column :results, :user_id, :integer
    add_index :results, :user_id
  end
end

quantified.rb

class Quantified < ActiveRecord::Base
	belongs_to :user
 	scope :averaged,  -> { where(categories: 'averaged') }
 	scope :instance,  -> { where(categories: 'instance') }
 	has_many :results
	accepts_nested_attributes_for :results, :reject_if => :all_blank, :allow_destroy => true

	CATEGORIES = ['averaged', 'instance']

end

result.rb

class Result < ActiveRecord::Base
	belongs_to :user
  belongs_to :quantified
end

完整跟踪

activemodel (4.2.0.rc3) lib/active_model/attribute_methods.rb:433:in `method_missing'
app/views/quantifieds/index.html.erb:18:in `block in _app_views_quantifieds_index_html_erb__3407997734302574408_70263238235460'
activerecord (4.2.0.rc3) lib/active_record/relation/delegation.rb:46:in `each'
activerecord (4.2.0.rc3) lib/active_record/relation/delegation.rb:46:in `each'
app/views/quantifieds/index.html.erb:9:in `_app_views_quantifieds_index_html_erb__3407997734302574408_70263238235460'
actionview (4.2.0.rc3) lib/action_view/template.rb:145:in `block in render'
activesupport (4.2.0.rc3) lib/active_support/notifications.rb:166:in `instrument'
actionview (4.2.0.rc3) lib/action_view/template.rb:333:in `instrument'
actionview (4.2.0.rc3) lib/action_view/template.rb:143:in `render'
actionview (4.2.0.rc3) lib/action_view/renderer/template_renderer.rb:54:in `block (2 levels) in render_template'
actionview (4.2.0.rc3) lib/action_view/renderer/abstract_renderer.rb:39:in `block in instrument'
activesupport (4.2.0.rc3) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.0.rc3) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.0.rc3) lib/active_support/notifications.rb:164:in `instrument'
actionview (4.2.0.rc3) lib/action_view/renderer/abstract_renderer.rb:39:in `instrument'
actionview (4.2.0.rc3) lib/action_view/renderer/template_renderer.rb:53:in `block in render_template'
actionview (4.2.0.rc3) lib/action_view/renderer/template_renderer.rb:61:in `render_with_layout'
actionview (4.2.0.rc3) lib/action_view/renderer/template_renderer.rb:52:in `render_template'
actionview (4.2.0.rc3) lib/action_view/renderer/template_renderer.rb:14:in `render'
actionview (4.2.0.rc3) lib/action_view/renderer/renderer.rb:42:in `render_template'
actionview (4.2.0.rc3) lib/action_view/renderer/renderer.rb:23:in `render'
actionview (4.2.0.rc3) lib/action_view/rendering.rb:100:in `_render_template'
actionpack (4.2.0.rc3) lib/action_controller/metal/streaming.rb:217:in `_render_template'
actionview (4.2.0.rc3) lib/action_view/rendering.rb:83:in `render_to_body'
actionpack (4.2.0.rc3) lib/action_controller/metal/rendering.rb:32:in `render_to_body'
actionpack (4.2.0.rc3) lib/action_controller/metal/renderers.rb:37:in `render_to_body'
actionpack (4.2.0.rc3) lib/abstract_controller/rendering.rb:25:in `render'
actionpack (4.2.0.rc3) lib/action_controller/metal/rendering.rb:16:in `render'
actionpack (4.2.0.rc3) lib/action_controller/metal/instrumentation.rb:41:in `block (2 levels) in render'
activesupport (4.2.0.rc3) lib/active_support/core_ext/benchmark.rb:12:in `block in ms'
/Users/galli01anthony/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/benchmark.rb:294:in `realtime'
activesupport (4.2.0.rc3) lib/active_support/core_ext/benchmark.rb:12:in `ms'
actionpack (4.2.0.rc3) lib/action_controller/metal/instrumentation.rb:41:in `block in render'
actionpack (4.2.0.rc3) lib/action_controller/metal/instrumentation.rb:84:in `cleanup_view_runtime'
activerecord (4.2.0.rc3) lib/active_record/railties/controller_runtime.rb:25:in `cleanup_view_runtime'
actionpack (4.2.0.rc3) lib/action_controller/metal/instrumentation.rb:40:in `render'
actionpack (4.2.0.rc3) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (4.2.0.rc3) lib/action_controller/metal/implicit_render.rb:5:in `send_action'
actionpack (4.2.0.rc3) lib/abstract_controller/base.rb:198:in `process_action'
actionpack (4.2.0.rc3) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (4.2.0.rc3) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:117:in `call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:117:in `call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:151:in `block in halting_and_conditional'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:151:in `call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:151:in `block in halting_and_conditional'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:151:in `call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:151:in `block in halting_and_conditional'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:234:in `call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:234:in `block in halting'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:234:in `call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:234:in `block in halting'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:169:in `call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:169:in `call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:169:in `call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:169:in `block in halting'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:92:in `call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:92:in `_run_callbacks'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:734:in `_run_process_action_callbacks'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.0.rc3) lib/abstract_controller/callbacks.rb:19:in `process_action'
actionpack (4.2.0.rc3) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (4.2.0.rc3) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
activesupport (4.2.0.rc3) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.0.rc3) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.0.rc3) lib/active_support/notifications.rb:164:in `instrument'
actionpack (4.2.0.rc3) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (4.2.0.rc3) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
activerecord (4.2.0.rc3) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (4.2.0.rc3) lib/abstract_controller/base.rb:137:in `process'
actionview (4.2.0.rc3) lib/action_view/rendering.rb:30:in `process'
actionpack (4.2.0.rc3) lib/action_controller/metal.rb:195:in `dispatch'
actionpack (4.2.0.rc3) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.2.0.rc3) lib/action_controller/metal.rb:236:in `block in action'
actionpack (4.2.0.rc3) lib/action_dispatch/routing/route_set.rb:73:in `call'
actionpack (4.2.0.rc3) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
actionpack (4.2.0.rc3) lib/action_dispatch/routing/route_set.rb:42:in `serve'
actionpack (4.2.0.rc3) lib/action_dispatch/journey/router.rb:43:in `block in serve'
actionpack (4.2.0.rc3) lib/action_dispatch/journey/router.rb:30:in `each'
actionpack (4.2.0.rc3) lib/action_dispatch/journey/router.rb:30:in `serve'
actionpack (4.2.0.rc3) lib/action_dispatch/routing/route_set.rb:802:in `call'
warden (1.2.3) lib/warden/manager.rb:35:in `block in call'
warden (1.2.3) lib/warden/manager.rb:34:in `catch'
warden (1.2.3) lib/warden/manager.rb:34: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.rc3) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.2.0.rc3) 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.rc3) lib/action_dispatch/middleware/cookies.rb:560:in `call'
activerecord (4.2.0.rc3) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.2.0.rc3) lib/active_record/connection_adapters/abstract/connection_pool.rb:647:in `call'
activerecord (4.2.0.rc3) lib/active_record/migration.rb:378:in `call'
actionpack (4.2.0.rc3) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:88:in `call'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:88:in `_run_callbacks'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:734:in `_run_call_callbacks'
activesupport (4.2.0.rc3) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.0.rc3) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.2.0.rc3) lib/action_dispatch/middleware/reloader.rb:73:in `call'
actionpack (4.2.0.rc3) lib/action_dispatch/middleware/remote_ip.rb:78:in `call'
actionpack (4.2.0.rc3) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.2.0.rc3) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.2.0.rc3) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.2.0.rc3) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.2.0.rc3) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.2.0.rc3) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.2.0.rc3) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.2.0.rc3) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.2.0.rc3) 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.rc3) 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.rc3) lib/action_dispatch/middleware/static.rb:113:in `call'
rack (1.6.0) lib/rack/sendfile.rb:113:in `call'
railties (4.2.0.rc3) lib/rails/engine.rb:518:in `call'
railties (4.2.0.rc3) 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'
/Users/galli01anthony/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/webrick/httpserver.rb:138:in `service'
/Users/galli01anthony/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/webrick/httpserver.rb:94:in `run'
/Users/galli01anthony/.rvm/rubies/ruby-2.1.3/lib/ruby/2.1.0/webrick/server.rb:295:in `block in start_thread'

如果您需要更多代码或评论来解决此问题，请与我们联系。上帝的速度。

Answer 1

回答您的具体问题：

在您的索引操作中，您有：

@quantified = Result.all.order("date_value")

在 .all 之前调用 .order 是导致错误的原因。

在Rails ActiveRecord中，.all命令立即触发从数据库中获取项目。

由于存在数据库IO提取命令.where和.order以形成从数据库中提取数据的方式（或什么），因此需要在数据库检索之前在代码中调用它们由.all：
之类的命令触发
@quantified = Result.order("date_value").all

为了更清楚，在此查询中指定升序或降序可能是理想的，例如， Result.order("date_value ASC").all，或者如果数据始终按此顺序使用，则可以在default_scope模型中为您排序Result。

调试Undefined Method“method_name”错误：时的
一般建议
在您的问题中，我注意到您没有包含受错误影响的对象的类信息，因此很难正确诊断问题的来源（您是否拥有正确的对象）。

提示：诊断错误时，请先查看对象是否存在，然后再查看错误标记的方法。

为什么呢？由于undefined method "method_name" method_name导致undefined错误不是实际上，而是因为对象本身是{{1}或者是一个不正确的类。

nil可能是一个红色鲱鱼，当您有一个未加载或实例化的对象时，会误导您。

要正确诊断NoMethodError，在开始尝试调试对象的NoMethodError: undefined method 'method_name'之前，必须先检查首先是否正确定义了对象的class。如果不这样做，就可以很容易地找到一个兔子洞，查看 method_name 可能存在的问题，而实际问题在于您的对象不存在。

要在undefined method错误中检查对象的类，只需查找错误的for xxx:Class部分。这描述了对象＆amp;它的班级。如果您的对象为零或不存在，则未定义的方法错误将显示 for nil:NilClass 。

NoMethodError: undefined method `date_time' for nil:NilClass

不幸的是，这里很容易专注于此错误消息的date_time部分，而不是NoMethodError消息引用 nil 类。在上面的NoMethodError中，我们的对象是 nil ，'date_time'只是代表一个代码中的一个点，我们不能在nil对象上调用一个方法。要正确解决nil：NilClass对象上的NoMethodError，重要的是调查为什么对象本身没有实例化。

索引中的NoMethodError：如何定义嵌套属性？

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