【问题标题】：Rails simple ajaxRails 简单的 ajax
【发布时间】：2015-11-01 09:56:26
【问题描述】：

所以我开始在 ruby on rails 上学习 ajax，很惭愧地问一些错误，但是这个错误很烦我，我不明白，这是因为我的操作系统（windows 10）或我的代码

所以我有5个文件，实际上我只是在从脚手架生成后编辑代码

该错误总是报错内部服务器（500），但我解决了2天，数据仍然插入数据库但div#data-list不会刷新

代码如下：

我的 index.html.erb ：

列出 ajaxxxes

<table>
  <thead>
    <tr>
      <th>Title</th>
      <th>Description</th>
      <th colspan="3"></th>
    </tr>
  </thead>
  <div id="data-list">
    <%= render 'data' %>
  </div>
</table>

<br>


<%= render 'form' %>

<%= link_to 'New Ajaxxx', new_ajaxxx_path %>

我的 _data.html.erb：

<tbody>
  <% @ajaxxxes.each do |ajaxxx| %>
      <tr>
        <td><%= ajaxxx.title %></td>
        <td><%= ajaxxx.description %></td>
        <td><%= link_to 'Show', ajaxxx %></td>
        <td><%= link_to 'Edit', edit_ajaxxx_path(ajaxxx) %></td>
        <td><%= link_to 'Destroy', ajaxxx, method: :delete, data: { confirm: 'Are you sure?' } %></td>
      </tr>
    <% end %>
  </tbody>

我的 _form.html.erb：

<%= form_for(@ajaxxx, remote: true) do |f| %>
  <% if @ajaxxx.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@ajaxxx.errors.count, "error") %> prohibited this ajaxxx from being saved:</h2>

      <ul>
      <% @ajaxxx.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :title %><br>
    <%= f.text_field :title %>
  </div>
  <div class="field">
    <%= f.label :description %><br>
    <%= f.text_area :description %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

我的 ajaxxxes_controller ：

class AjaxxxesController < ApplicationController
   before_action :set_ajaxxx, only: [:show, :edit, :update, :destroy]

  # GET /ajaxxxes
  # GET /ajaxxxes.json
  def index
    @ajaxxxes = Ajaxxx.all
    @ajaxxx = Ajaxxx.new
  end

  # GET /ajaxxxes/new
  def new
    @ajaxxx = Ajaxxx.new
  end

  # POST /ajaxxxes
  # POST /ajaxxxes.json
  def create
    @ajaxxx = Ajaxxx.new(ajaxxx_params)

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


  private
    # Use callbacks to share common setup or constraints between actions.
    def set_ajaxxx
      @ajaxxx = Ajaxxx.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def ajaxxx_params
      params.require(:ajaxxx).permit(:title, :description)
    end
end

最后是我的 create.js.erb ：

<% if @ajaxxx.title %>
            console.log("Ajaxxx created!");
            $("#data-list").html("<%= escape_javascript(render 'data') %>");
         <% else %>
            console.log("Failed");
         <% end %>

这是日志：

    Started GET "/" for 127.0.0.1 at 2015-11-01 17:06:01 +0700
      [1m[36mActiveRecord::SchemaMigration Load (0.0ms)[0m  [1mSELECT "schema_migrations".* FROM "schema_migrations"[0m
    Processing by AjaxxxesController#index as HTML
      [1m[35mAjaxxx Load (0.0ms)[0m  SELECT "ajaxxxes".* FROM "ajaxxxes"
      Rendered ajaxxxes/_data.html.erb (24.0ms)
      Rendered ajaxxxes/_form.html.erb (60.0ms)
      Rendered ajaxxxes/index.html.erb within layouts/application (160.0ms)
    Completed 200 OK in 468ms (Views: 438.2ms | ActiveRecord: 0.0ms)


    Started GET "/assets/searches.css?body=1" for 127.0.0.1 at 2015-11-01 17:06:02 +0700


    Started GET "/assets/jquery.js?body=1" for 127.0.0.1 at 2015-11-01 17:06:02 +0700


    Started GET "/assets/ajaxxxes.js?body=1" for 127.0.0.1 at 2015-11-01 17:06:02 +0700


    Started GET "/assets/application.css?body=1" for 127.0.0.1 at 2015-11-01 17:06:02 +0700


    Started GET "/assets/jquery_ujs.js?body=1" for 127.0.0.1 at 2015-11-01 17:06:02 +0700


    Started GET "/assets/turbolinks.js?body=1" for 127.0.0.1 at 2015-11-01 17:06:02 +0700


    Started GET "/assets/indices.js?body=1" for 127.0.0.1 at 2015-11-01 17:06:02 +0700


    Started GET "/assets/items.js?body=1" for 127.0.0.1 at 2015-11-01 17:06:02 +0700


    Started GET "/assets/searches.js?body=1" for 127.0.0.1 at 2015-11-01 17:06:02 +0700


    Started GET "/assets/application.js?body=1" for 127.0.0.1 at 2015-11-01 17:06:02 +0700


    Started POST "/ajaxxxes" for 127.0.0.1 at 2015-11-01 17:06:19 +0700
    Processing by AjaxxxesController#create as JS
      Parameters: {"utf8"=>"✓", "ajaxxx"=>{"title"=>"Test-51", "description"=>"Test-51"}, "commit"=>"Create Ajaxxx"}
      [1m[36m (0.0ms)[0m  [1mbegin transaction[0m
      [1m[35mSQL (0.0ms)[0m  INSERT INTO "ajaxxxes" ("created_at", "description", "title", "updated_at") VALUES (?, ?, ?, ?)  [["created_at", "2015-11-01 10:06:19.915267"], ["description", "Test-51"], ["title", "Test-51"], ["updated_at", "2015-11-01 10:06:19.915267"]]
      [1m[36m (15.6ms)[0m  [1mcommit transaction[0m
      Rendered ajaxxxes/_data.html.erb (62.5ms)
      Rendered ajaxxxes/create.js.erb (109.4ms)
    Completed 500 Internal Server Error in 344ms

    ActionView::Template::Error (undefined method `each' for nil:NilClass):
        1: <tbody>
        2:     <% @ajaxxxes.each do |ajaxxx| %>
        3:       <tr>
        4:         <td><%= ajaxxx.title %></td>
        5:         <td><%= ajaxxx.description %></td>
      app/views/ajaxxxes/_data.html.erb:2:in `_app_views_ajaxxxes__data_html_erb___834628740_45308136'
      app/views/ajaxxxes/create.js.erb:3:in `_app_views_ajaxxxes_create_js_erb___336360114_45416052'
      app/controllers/ajaxxxes_controller.rb:30:in `create'


      Rendered C:/Ruby22/lib/ruby/gems/2.2.0/gems/actionpack-4.1.8/lib/action_dispatch/middleware/templates/rescues/_trace.text.erb (0.0ms)
      Rendered C:/Ruby22/lib/ruby/gems/2.2.0/gems/actionpack-4.1.8/lib/action_dispatch/middleware/templates/rescues/_request_and_response.text.erb (0.0ms)
      Rendered C:/Ruby22/lib/ruby/gems/2.2.0/gems/actionpack-4.1.8/lib/action_dispatch/middleware/templates/rescues/template_error.text.erb (665.1ms)

【问题讨论】：

标签： javascript ruby-on-rails ruby ajax ruby-on-rails-4

【解决方案1】：

这是错误：

 ActionView::Template::Error (undefined method `each' for nil:NilClass):
        1: <tbody>
        2:     <% @ajaxxxes.each do |ajaxxx| %>

问题是您的@ajaxxxes 变量未定义。

此错误出现在app/controllers/ajaxxxes_controller.rb:30:in create（format.js 行，它调用/app/views/ajaxxxes/create.js.erb：

<% if @ajaxxx.title %>
   console.log("Ajaxxx created!");
   $("#data-list").html("<%= escape_javascript(render 'data') %>");
<% else %>
   console.log("Failed");
<% end %>

这里的问题是：<%= escape_javascript(render 'data') %>

app/views/ajaxxxes/_data.html.erb 包含对@ajaxxxes 的引用：

<tbody>
  <% @ajaxxxes.each do |ajaxxx| %>

Rails partials 旨在从应用程序的任何部分调用。因此，您应该从不在其中引用@instance 变量（该变量可能不可用，因为在这种情况下不可用）。

因此，解决您的错误的方法是或者使用"local" variables，或者省略从create.js.erb 调用data：

#app/views/ajaxxxes/create.js.erb
<% if @ajaxxx.title %>
   console.log("Ajaxxx created!");
   $("#data-list").html("<%=j render 'data', locals: {ajaxxxes: @ajaxxxes} %>");
<% else %>
   console.log("Failed");
<% end %>

#app/controllers/ajaxxxes_controller.rb
class AjaxxxesController < ApplicationController
   def create
      @ajaxxxes = Ajaxxx.all
      ...
   end
end

#app/views/ajaxxxes/_data.html.erb
<tbody>
  <% ajaxxxes.each do |ajaxxx| %>
      <tr>
        <td><%= ajaxxx.title %></td>
        <td><%= ajaxxx.description %></td>
        <td><%= link_to 'Show', ajaxxx %></td>
        <td><%= link_to 'Edit', edit_ajaxxx_path(ajaxxx) %></td>
        <td><%= link_to 'Destroy', ajaxxx, method: :delete, data: { confirm: 'Are you sure?' } %></td>
      </tr>
    <% end %>
</tbody>

【讨论】：

【解决方案2】：

错误信息很清楚：

ActionView::Template::Error (undefined method `each' for nil:NilClass):
    1: <tbody>
    2:     <% @ajaxxxes.each do |ajaxxx| %>

这意味着@ajaxxxes 变量是nil 而不是数组。请检查您相应的控制器方法是否缺少对@ajaxxxes 的分配（或者可能有错字）。

【讨论】：

【解决方案3】：

ActionView::Template::Error（未定义的方法 `each' nil:NilClass)

问题出在这一行

<% @ajaxxxes.each do |ajaxxx| %>

由于代码属于部分，您应该在渲染部分时将实例变量（@ajaxxxes）作为局部变量传递

以下更改应该有效

<%= render 'data', ajaxxxes: @ajaxxxes %>

然后改变

<% @ajaxxxes.each do |ajaxxx| %>

到

<% ajaxxxes.each do |ajaxxx| %>

【讨论】：