简易导轨关联

我是RoR的新手。我正在尝试创建一个基本的Web应用程序，其中一个配置文件页面显示了属于特定配置文件的项目列表。简易导轨关联

到目前为止，我有：

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

在情景模式：has_many :items在项目模型：belongs_to :profile

当我尝试创建一个新的配置文件，我得到的错误：

undefined method `item' for #<Profile

简介控制器

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

档案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 %>

档案_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 %>

完整的错误跟踪：

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'

来源

2013-03-22 mnort9

什么呢你新创建的行动是什么样子？ – Wasi 2013-03-22 01:55:32

上面已添加... – mnort9 2013-03-22 01:59:57

您没有创建操作。请看看我的答案，看看是否有助于你理解。另外，为您的配置文件提供您的index.html视图的代码或错误的完整堆栈跟踪。看来你在某处调用profile.item。 – 2013-03-22 02:02:50

为了使has_many :items工作，你将需要在您的Item模型中有profile_id:integer。

您可以通过执行以下命令

rails g migration add_profile_id_to_items profile_id:integer 
rake db:migrate

这应该创造必要的关联外键完成。

这之后，你应该能够做这样的事情

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

有不同的方式，为配置文件创建项目，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

来源

2013-03-22 02:00:24

首先，你的个人资料对象不具有“项目”字段。通过执行这些命令检查对象的属性：

rails console 
Profile.connection 
Profile

或访问您的文件db/schema.rb

你会看到，没有属性：项目在对象的哈希值。

您可能想要在您的show.html.erb视图中显示配置文件的项目。但首先，你需要创建一个属于像这样分布的Item：

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

然后，你可以这样做：

Profile.first.items

其次，你在你的控制器有一个错误。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

来源

2017-03-01 14:55:02 jedi

简易导轨关联

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