用于NilClass的未定义方法`model_name`：Class

时间：2014-01-07 14:03:19

标签： ruby-on-rails ruby

我正在尝试允许用户对指南发表评论。错误发生在以下代码的第一行。这是评论形式的部分：

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

  <div class="form-inputs">
    <%= f.input :body %>
    <%= f.hidden_field :guide %>
    <%= f.hidden_field :user %>
  </div>

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

这是user.rb：

class User < ActiveRecord::Base
  has_many :guides
  has_many :comments
end

comment.rb

class Comment < ActiveRecord::Base
  belongs_to :guide
  belongs_to :user
end

class Guide < ActiveRecord::Base
  belongs_to :user
  has_many :comments
end

以下是路线：

Runescapeguides::Application.routes.draw do
  resources :comments

  devise_for :users

  resources :guides do
    member do
      put "like", to: "guides#upvote"
      put "dislike", to: "guides#downvote"
    end
  end
end

以下是整个评论控制器：

class CommentsController < ApplicationController
  before_action :set_comment, only: [:show, :edit, :update, :destroy]

  # GET /comments
  # GET /comments.json
  def index
    @comments = Comment.all
  end

  # GET /comments/1
  # GET /comments/1.json
  def show
  end

  # GET /comments/new
  def new
    @comment = Comment.new
  end

  # GET /comments/1/edit
  def edit
  end

  # POST /comments
  # POST /comments.json
  def create
    @comment = Comment.new(comment_params)

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

  # PATCH/PUT /comments/1
  # PATCH/PUT /comments/1.json
  def update
    respond_to do |format|
      if @comment.update(comment_params)
        format.html { redirect_to @comment, notice: 'Comment was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: 'edit' }
        format.json { render json: @comment.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /comments/1
  # DELETE /comments/1.json
  def destroy
    @comment.destroy
    respond_to do |format|
      format.html { redirect_to comments_url }
      format.json { head :no_content }
    end
  end

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

    # Never trust parameters from the scary internet, only allow the white list through.
    def comment_params
      params.require(:comment).permit(:body, :guide_id, :user_id)
    end
end

请求的完整堆栈跟踪：

actionpack (4.0.2) lib/action_controller/model_naming.rb:9:in `model_name_from_record_or_class'
actionpack (4.0.2) lib/action_view/record_identifier.rb:47:in `dom_class'
simple_form (3.0.1) lib/simple_form/action_view_extensions/form_helper.rb:58:in `simple_form_css_class'
simple_form (3.0.1) lib/simple_form/action_view_extensions/form_helper.rb:19:in `simple_form_for'
app/views/comments/_form.html.erb:1:in `_app_views_comments__form_html_erb___400129178956723429_2211455180'
actionpack (4.0.2) lib/action_view/template.rb:143:in `block in render'
activesupport (4.0.2) lib/active_support/notifications.rb:161:in `instrument'
actionpack (4.0.2) lib/action_view/template.rb:141:in `render'
actionpack (4.0.2) lib/action_view/renderer/partial_renderer.rb:306:in `render_partial'
actionpack (4.0.2) lib/action_view/renderer/partial_renderer.rb:279:in `block in render'
actionpack (4.0.2) lib/action_view/renderer/abstract_renderer.rb:38:in `block in instrument'
activesupport (4.0.2) lib/active_support/notifications.rb:159:in `block in instrument'
activesupport (4.0.2) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.0.2) lib/active_support/notifications.rb:159:in `instrument'
actionpack (4.0.2) lib/action_view/renderer/abstract_renderer.rb:38:in `instrument'
actionpack (4.0.2) lib/action_view/renderer/partial_renderer.rb:278:in `render'
actionpack (4.0.2) lib/action_view/renderer/renderer.rb:47:in `render_partial'
actionpack (4.0.2) lib/action_view/helpers/rendering_helper.rb:27:in `render'
app/views/guides/show.html.erb:29:in `_app_views_guides_show_html_erb___4114194112307075162_2193467420'
actionpack (4.0.2) lib/action_view/template.rb:143:in `block in render'
activesupport (4.0.2) lib/active_support/notifications.rb:161:in `instrument'
actionpack (4.0.2) lib/action_view/template.rb:141:in `render'
actionpack (4.0.2) lib/action_view/renderer/template_renderer.rb:49:in `block (2 levels) in render_template'
actionpack (4.0.2) lib/action_view/renderer/abstract_renderer.rb:38:in `block in instrument'
activesupport (4.0.2) lib/active_support/notifications.rb:159:in `block in instrument'
activesupport (4.0.2) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.0.2) lib/active_support/notifications.rb:159:in `instrument'
actionpack (4.0.2) lib/action_view/renderer/abstract_renderer.rb:38:in `instrument'
actionpack (4.0.2) lib/action_view/renderer/template_renderer.rb:48:in `block in render_template'
actionpack (4.0.2) lib/action_view/renderer/template_renderer.rb:56:in `render_with_layout'
actionpack (4.0.2) lib/action_view/renderer/template_renderer.rb:47:in `render_template'
actionpack (4.0.2) lib/action_view/renderer/template_renderer.rb:17:in `render'
actionpack (4.0.2) lib/action_view/renderer/renderer.rb:42:in `render_template'
actionpack (4.0.2) lib/action_view/renderer/renderer.rb:23:in `render'
actionpack (4.0.2) lib/abstract_controller/rendering.rb:127:in `_render_template'
actionpack (4.0.2) lib/action_controller/metal/streaming.rb:219:in `_render_template'
actionpack (4.0.2) lib/abstract_controller/rendering.rb:120:in `render_to_body'
actionpack (4.0.2) lib/action_controller/metal/rendering.rb:33:in `render_to_body'
actionpack (4.0.2) lib/action_controller/metal/renderers.rb:26:in `render_to_body'
actionpack (4.0.2) lib/abstract_controller/rendering.rb:97:in `render'
actionpack (4.0.2) lib/action_controller/metal/rendering.rb:16:in `render'
actionpack (4.0.2) lib/action_controller/metal/instrumentation.rb:41:in `block (2 levels) in render'
activesupport (4.0.2) lib/active_support/core_ext/benchmark.rb:12:in `block in ms'
/Users/DylanRichards/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/benchmark.rb:296:in `realtime'
activesupport (4.0.2) lib/active_support/core_ext/benchmark.rb:12:in `ms'
actionpack (4.0.2) lib/action_controller/metal/instrumentation.rb:41:in `block in render'
actionpack (4.0.2) lib/action_controller/metal/instrumentation.rb:84:in `cleanup_view_runtime'
activerecord (4.0.2) lib/active_record/railties/controller_runtime.rb:25:in `cleanup_view_runtime'
actionpack (4.0.2) lib/action_controller/metal/instrumentation.rb:40:in `render'
actionpack (4.0.2) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (4.0.2) lib/action_controller/metal/implicit_render.rb:5:in `send_action'
actionpack (4.0.2) lib/abstract_controller/base.rb:189:in `process_action'
actionpack (4.0.2) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (4.0.2) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (4.0.2) lib/active_support/callbacks.rb:433:in `_run__3967050594013931216__process_action__callbacks'
activesupport (4.0.2) lib/active_support/callbacks.rb:80:in `run_callbacks'
actionpack (4.0.2) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (4.0.2) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (4.0.2) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
activesupport (4.0.2) lib/active_support/notifications.rb:159:in `block in instrument'
activesupport (4.0.2) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.0.2) lib/active_support/notifications.rb:159:in `instrument'
actionpack (4.0.2) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (4.0.2) lib/action_controller/metal/params_wrapper.rb:245:in `process_action'
activerecord (4.0.2) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (4.0.2) lib/abstract_controller/base.rb:136:in `process'
actionpack (4.0.2) lib/abstract_controller/rendering.rb:44:in `process'
actionpack (4.0.2) lib/action_controller/metal.rb:195:in `dispatch'
actionpack (4.0.2) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.0.2) lib/action_controller/metal.rb:231:in `block in action'
actionpack (4.0.2) lib/action_dispatch/routing/route_set.rb:80:in `call'
actionpack (4.0.2) lib/action_dispatch/routing/route_set.rb:80:in `dispatch'
actionpack (4.0.2) lib/action_dispatch/routing/route_set.rb:48:in `call'
actionpack (4.0.2) lib/action_dispatch/journey/router.rb:71:in `block in call'
actionpack (4.0.2) lib/action_dispatch/journey/router.rb:59:in `each'
actionpack (4.0.2) lib/action_dispatch/journey/router.rb:59:in `call'
actionpack (4.0.2) lib/action_dispatch/routing/route_set.rb:680: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 (1.5.2) lib/rack/etag.rb:23:in `call'
rack (1.5.2) lib/rack/conditionalget.rb:25:in `call'
rack (1.5.2) lib/rack/head.rb:11:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/flash.rb:241:in `call'
rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/cookies.rb:486:in `call'
activerecord (4.0.2) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.0.2) lib/active_record/connection_adapters/abstract/connection_pool.rb:626:in `call'
activerecord (4.0.2) lib/active_record/migration.rb:369:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.0.2) lib/active_support/callbacks.rb:373:in `_run__2558488765796940480__call__callbacks'
activesupport (4.0.2) lib/active_support/callbacks.rb:80:in `run_callbacks'
actionpack (4.0.2) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/reloader.rb:64:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.0.2) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.0.2) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.0.2) lib/active_support/tagged_logging.rb:67:in `block in tagged'
activesupport (4.0.2) lib/active_support/tagged_logging.rb:25:in `tagged'
activesupport (4.0.2) lib/active_support/tagged_logging.rb:67:in `tagged'
railties (4.0.2) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
rack (1.5.2) lib/rack/runtime.rb:17:in `call'
activesupport (4.0.2) lib/active_support/cache/strategy/local_cache.rb:83:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/static.rb:64:in `call'
rack (1.5.2) lib/rack/sendfile.rb:112:in `call'
railties (4.0.2) lib/rails/engine.rb:511:in `call'
railties (4.0.2) lib/rails/application.rb:97:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
rack (1.5.2) lib/rack/content_length.rb:14:in `call'
rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service'
/Users/DylanRichards/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/httpserver.rb:138:in `service'
/Users/DylanRichards/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/httpserver.rb:94:in `run'
/Users/DylanRichards/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/server.rb:295:in `block in start_thread'

如何正确显示评论？

1 个答案:

答案 0 :(得分：2)

您的代码中存在错误。您发布了一个CommentsController，但您的错误显示已调用的视图是guides视图（应该属于GuidesController）

app/views/guides/show.html.erb:29:in `_app_views_guides_show_html_erb___4114194112307075162_2193467420'

并且路由仅包含:guides资源，而不包含注释。从不使用评论控制器。

如果要将编辑指向该控制器，则需要关联路径。

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