Question

我正在使用gmaps4rails，当我尝试创建一个新位置时，我收到错误消息：'undefined方法`model_name'代表NilClass：Class'

Extracted source (around line #1):

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

这是控制器：

class LocationsController < ApplicationController
  # GET /locations
  # GET /locations.json

  def index
    @locations = Location.all
    @json = Location.all.to_gmaps4rails
    end
    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @locations }
    end
  end

  # GET /locations/1
  # GET /locations/1.json
  def show
    @location = Location.find(params[:id])
    @json = Location.all.to_gmaps4rails
    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @location }
    end
  end

  # GET /locations/new
  # GET /locations/new.json
  def new
    #@location = Location.new
    @json = Location.all.to_gmaps4rails

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

  # GET /locations/1/edit
  def edit
    @location = Location.find(params[:id])
    @json = Location.all.to_gmaps4rails
  end

  # POST /locations
  # POST /locations.json
  def create
    #@location = Location.new(params[:location])
    @json = Location.all.to_gmaps4rails
    respond_to do |format|
      if @location.save
        format.html { redirect_to @location, notice: 'Location was successfully created.' }
        format.json { render json: @location, status: :created, location: @location }
      else
        format.html { render action: "new" }
        format.json { render json: @location.errors, status: :unprocessable_entity }
      end
    end
  end

  # PUT /locations/1
  # PUT /locations/1.json
  def update
    @location = Location.find(params[:id])
    @json = Location.all.to_gmaps4rails
    respond_to do |format|
      if @location.update_attributes(params[:location])
        format.html { redirect_to @location, notice: 'Location was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @location.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /locations/1
  # DELETE /locations/1.json
  def destroy
    @location = Location.find(params[:id])
    @location.destroy
    @json = Location.all.to_gmaps4rails
    respond_to do |format|
      format.html { redirect_to locations_url }
      format.json { head :no_content }
    end
  end

模型看起来像这样：

class Location < ActiveRecord::Base
  attr_accessible :college_id, :course_id, :id, :name, :latitude, :longitude, :gmaps, :address

  belongs_to :college
  has_many :courses
  acts_as_gmappable

  def gmaps4rails_address
    address
  end

end

和完整的痕迹：

activemodel (3.2.9) lib/active_model/naming.rb:163:in `model_name_from_record_or_class'
activemodel (3.2.9) lib/active_model/naming.rb:158:in `param_key'
actionpack (3.2.9) lib/action_view/helpers/form_helper.rb:369:in `form_for'
app/views/locations/_form.html.erb:1:in `_app_views_locations__form_html_erb___716241816_58056000'
actionpack (3.2.9) lib/action_view/template.rb:145:in `block in render'
activesupport (3.2.9) lib/active_support/notifications.rb:125:in `instrument'
actionpack (3.2.9) lib/action_view/template.rb:143:in `render'
actionpack (3.2.9) lib/action_view/renderer/partial_renderer.rb:265:in `render_partial'
actionpack (3.2.9) lib/action_view/renderer/partial_renderer.rb:238:in `block in render'
actionpack (3.2.9) lib/action_view/renderer/abstract_renderer.rb:38:in `block in instrument'
activesupport (3.2.9) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.9) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.9) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.9) lib/action_view/renderer/abstract_renderer.rb:38:in `instrument'
actionpack (3.2.9) lib/action_view/renderer/partial_renderer.rb:237:in `render'
actionpack (3.2.9) lib/action_view/renderer/renderer.rb:41:in `render_partial'
actionpack (3.2.9) lib/action_view/helpers/rendering_helper.rb:27:in `render'
app/views/locations/new.html.erb:3:in `_app_views_locations_new_html_erb___791287105_46366992'
actionpack (3.2.9) lib/action_view/template.rb:145:in `block in render'
activesupport (3.2.9) lib/active_support/notifications.rb:125:in `instrument'
actionpack (3.2.9) lib/action_view/template.rb:143:in `render'
actionpack (3.2.9) lib/action_view/renderer/template_renderer.rb:47:in `block (2 levels) in render_template'
actionpack (3.2.9) lib/action_view/renderer/abstract_renderer.rb:38:in `block in instrument'
activesupport (3.2.9) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.9) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.9) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.9) lib/action_view/renderer/abstract_renderer.rb:38:in `instrument'
actionpack (3.2.9) lib/action_view/renderer/template_renderer.rb:46:in `block in render_template'
actionpack (3.2.9) lib/action_view/renderer/template_renderer.rb:54:in `render_with_layout'
actionpack (3.2.9) lib/action_view/renderer/template_renderer.rb:45:in `render_template'
actionpack (3.2.9) lib/action_view/renderer/template_renderer.rb:18:in `render'
actionpack (3.2.9) lib/action_view/renderer/renderer.rb:36:in `render_template'
actionpack (3.2.9) lib/action_view/renderer/renderer.rb:17:in `render'
actionpack (3.2.9) lib/abstract_controller/rendering.rb:110:in `_render_template'
actionpack (3.2.9) lib/action_controller/metal/streaming.rb:225:in `_render_template'
actionpack (3.2.9) lib/abstract_controller/rendering.rb:103:in `render_to_body'
actionpack (3.2.9) lib/action_controller/metal/renderers.rb:28:in `render_to_body'
actionpack (3.2.9) lib/action_controller/metal/compatibility.rb:50:in `render_to_body'
actionpack (3.2.9) lib/abstract_controller/rendering.rb:88:in `render'
actionpack (3.2.9) lib/action_controller/metal/rendering.rb:16:in `render'
actionpack (3.2.9) lib/action_controller/metal/instrumentation.rb:40:in `block (2 levels) in render'
activesupport (3.2.9) lib/active_support/core_ext/benchmark.rb:5:in `block in ms'
C:/Ruby192/lib/ruby/1.9.1/benchmark.rb:310:in `realtime'
activesupport (3.2.9) lib/active_support/core_ext/benchmark.rb:5:in `ms'
actionpack (3.2.9) lib/action_controller/metal/instrumentation.rb:40:in `block in render'
actionpack (3.2.9) lib/action_controller/metal/instrumentation.rb:83:in `cleanup_view_runtime'
activerecord (3.2.9) lib/active_record/railties/controller_runtime.rb:24:in `cleanup_view_runtime'
actionpack (3.2.9) lib/action_controller/metal/instrumentation.rb:39:in `render'
actionpack (3.2.9) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (3.2.9) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (3.2.9) lib/abstract_controller/base.rb:167:in `process_action'
actionpack (3.2.9) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (3.2.9) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.2.9) lib/active_support/callbacks.rb:414:in `_run__350059794__process_action__911521287__callbacks'
activesupport (3.2.9) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.9) lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks'
activesupport (3.2.9) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.9) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.2.9) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (3.2.9) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
activesupport (3.2.9) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.9) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.9) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.9) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.2.9) lib/action_controller/metal/params_wrapper.rb:207:in `process_action'
activerecord (3.2.9) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (3.2.9) lib/abstract_controller/base.rb:121:in `process'
actionpack (3.2.9) lib/abstract_controller/rendering.rb:45:in `process'
actionpack (3.2.9) lib/action_controller/metal.rb:203:in `dispatch'
actionpack (3.2.9) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.2.9) lib/action_controller/metal.rb:246:in `block in action'
actionpack (3.2.9) lib/action_dispatch/routing/route_set.rb:73:in `call'
actionpack (3.2.9) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
actionpack (3.2.9) 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 (3.2.9) 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 (3.2.9) 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 (3.2.9) lib/action_dispatch/middleware/head.rb:14:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.2.9) 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 (3.2.9) lib/action_dispatch/middleware/cookies.rb:341:in `call'
activerecord (3.2.9) lib/active_record/query_cache.rb:64:in `call'
activerecord (3.2.9) lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (3.2.9) lib/active_support/callbacks.rb:405:in `_run__341585242__call__226313936__callbacks'
activesupport (3.2.9) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.9) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
activesupport (3.2.9) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.9) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/reloader.rb:65:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
railties (3.2.9) lib/rails/rack/logger.rb:32:in `call_app'
railties (3.2.9) lib/rails/rack/logger.rb:16:in `block in call'
activesupport (3.2.9) lib/active_support/tagged_logging.rb:22:in `tagged'
railties (3.2.9) lib/rails/rack/logger.rb:16:in `call'
actionpack (3.2.9) 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 (3.2.9) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.4.5) lib/rack/lock.rb:15:in `call'
actionpack (3.2.9) lib/action_dispatch/middleware/static.rb:62:in `call'
railties (3.2.9) lib/rails/engine.rb:479:in `call'
railties (3.2.9) lib/rails/application.rb:223:in `call'
rack (1.4.5) lib/rack/content_length.rb:14:in `call'
railties (3.2.9) lib/rails/rack/log_tailer.rb:17:in `call'
rack (1.4.5) lib/rack/handler/webrick.rb:59:in `service'
C:/Ruby192/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
C:/Ruby192/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
C:/Ruby192/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'

有人能指出我正确的方向吗？

谢谢你！

Ĵ

Answer 1

实际上，您不会在控制器中创建任何位置，@location为nil。这些行应不进行评论：

@location = Location.new # in locations#new

@location = Location.new(params[:location]) # in locations#create

Answer 2

控制器代码底部缺少

结束标签........不再说......

gmaps4rails = NilClass的未定义方法`model_name'：Class

2 个答案: