尝试在 ruby on rails 中创建嵌套资源时，“表单中的第一个参数不能包含 nil 或为空”
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【中文标题】尝试在 ruby on rails 中创建嵌套资源时，“表单中的第一个参数不能包含 nil 或为空”【英文标题】："First argument in form cannot contain nil or be empty" when trying to create a nested resource in ruby on rails 【发布时间】：2016-05-05 16:35:39 【问题描述】：在我的应用程序中，我正在尝试创建一个嵌套资源（针对给定目标的一个步骤），但在 URL“/goals/1/steps/new”处创建时遇到了问题。当我导航到该页面时，我收到错误“表单中的第一个参数不能包含 nil 或为空”
我真的不明白为什么我不能创建一个步骤，它在创建时分配给它创建的特定对象。非常感谢任何帮助。
以下是我的步数控制器和我的步数表单
步骤控制器：
class StepsController < ApplicationController
#before_action :set_step, only: [:show, :edit, :update, :destroy]
before_filter :authorize
# GET /steps
# GET /steps.json
def index
@steps = Goal.find(params[:goal_id]).steps.all
end
# GET /goals/1/steps/new
def new
@step = Goal.find(params[:goal_id]).steps.new
end
# GET /steps/1
# GET /steps/1.json
def show
end
# GET /steps/1/edit
def edit
end
def create
@step = Goal.find(params[:goal_id]).steps.new(step_params)
respond_to do |format|
if @step.save
format.html redirect_to @step, notice: 'Step was successfully created.'
format.json render :show, status: :created, location: @step
else
format.html render :new
format.json render json: @step.errors, status: :unprocessable_entity
end
end
redirect_to(goal_steps_url(@goal))
end
def update
@step.update(step_params)
respond_to do |format|
if @step.update(step_params)
format.html redirect_to @step, notice: 'Step was successfully updated.'
format.json render :show, status: :ok, location: @step
else
format.html render :edit
format.json render json: @step.errors, status: :unprocessable_entity
end
end
end
# POST /steps
# POST /steps.json
def destroy
@step.destroy
respond_to do |format|
format.html redirect_to steps_url, notice: 'Step was successfully destroyed.'
format.json head :no_content
end
end
private
def set_step
@step = Goal.find(params[:goal_id]).Step.find(params[:id])
end
def step_params
params.require(:step).permit(:requirement, :completionTime, :goal_id)
end
end
步骤形式：
<%= form_for(@steps) do |f| %>
<% if @step.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(@step.errors.count, "error") %> prohibited this step from being saved:</h2>
<ul>
<% @step.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.label :requirement %><br>
<%= f.text_field :requirement %>
</div>
<div class="field">
<%= f.label :completionTime %><br>
<%= f.number_field :completionTime %>
</div>
<div class="field">
<%= hidden_field_tag :goal_id, goal.id %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
路由文件：
Rails.application.routes.draw do
resources :goals do
resources :steps
end
resources :signups
get 'welcome/index'
resources :calendar
resources :todolist
resources :to_dos
root 'welcome#index'
# These routes will be for signup. The first renders a form in the browse, the second will
# receive the form and create a user in our database using the data given to us by the user.
get '/login' => 'sessions#new'
post '/login' => 'sessions#create'
get '/logout' => 'sessions#destroy'
get '/signup' => 'users#new'
post '/users' => 'users#create'
end
堆栈跟踪：
actionview (4.2.5.1) lib/action_view/helpers/form_helper.rb:432:in `form_for'
app/views/steps/_form.html.erb:1:in `_app_views_steps__form_html_erb__4323915558924223187_70260809990920'
actionview (4.2.5.1) lib/action_view/template.rb:145:in `block in render'
activesupport (4.2.5.1) lib/active_support/notifications.rb:166:in `instrument'
actionview (4.2.5.1) lib/action_view/template.rb:333:in `instrument'
actionview (4.2.5.1) lib/action_view/template.rb:143:in `render'
actionview (4.2.5.1) lib/action_view/renderer/partial_renderer.rb:339:in `render_partial'
actionview (4.2.5.1) lib/action_view/renderer/partial_renderer.rb:310:in `block in render'
actionview (4.2.5.1) lib/action_view/renderer/abstract_renderer.rb:39:in `block in instrument'
activesupport (4.2.5.1) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.5.1) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.5.1) lib/active_support/notifications.rb:164:in `instrument'
actionview (4.2.5.1) lib/action_view/renderer/abstract_renderer.rb:39:in `instrument'
actionview (4.2.5.1) lib/action_view/renderer/partial_renderer.rb:309:in `render'
actionview (4.2.5.1) lib/action_view/renderer/renderer.rb:47:in `render_partial'
actionview (4.2.5.1) lib/action_view/helpers/rendering_helper.rb:35:in `render'
app/views/steps/new.html.erb:3:in `_app_views_steps_new_html_erb__538834525682328601_70260798181140'
actionview (4.2.5.1) lib/action_view/template.rb:145:in `block in render'
activesupport (4.2.5.1) lib/active_support/notifications.rb:166:in `instrument'
actionview (4.2.5.1) lib/action_view/template.rb:333:in `instrument'
actionview (4.2.5.1) lib/action_view/template.rb:143:in `render'
actionview (4.2.5.1) lib/action_view/renderer/template_renderer.rb:54:in `block (2 levels) in render_template'
actionview (4.2.5.1) lib/action_view/renderer/abstract_renderer.rb:39:in `block in instrument'
activesupport (4.2.5.1) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.5.1) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.5.1) lib/active_support/notifications.rb:164:in `instrument'
actionview (4.2.5.1) lib/action_view/renderer/abstract_renderer.rb:39:in `instrument'
actionview (4.2.5.1) lib/action_view/renderer/template_renderer.rb:53:in `block in render_template'
actionview (4.2.5.1) lib/action_view/renderer/template_renderer.rb:61:in `render_with_layout'
actionview (4.2.5.1) lib/action_view/renderer/template_renderer.rb:52:in `render_template'
actionview (4.2.5.1) lib/action_view/renderer/template_renderer.rb:14:in `render'
actionview (4.2.5.1) lib/action_view/renderer/renderer.rb:42:in `render_template'
actionview (4.2.5.1) lib/action_view/renderer/renderer.rb:23:in `render'
actionview (4.2.5.1) lib/action_view/rendering.rb:100:in `_render_template'
actionpack (4.2.5.1) lib/action_controller/metal/streaming.rb:217:in `_render_template'
actionview (4.2.5.1) lib/action_view/rendering.rb:83:in `render_to_body'
actionpack (4.2.5.1) lib/action_controller/metal/rendering.rb:32:in `render_to_body'
actionpack (4.2.5.1) lib/action_controller/metal/renderers.rb:37:in `render_to_body'
actionpack (4.2.5.1) lib/abstract_controller/rendering.rb:25:in `render'
actionpack (4.2.5.1) lib/action_controller/metal/rendering.rb:16:in `render'
actionpack (4.2.5.1) lib/action_controller/metal/instrumentation.rb:44:in `block (2 levels) in render'
activesupport (4.2.5.1) lib/active_support/core_ext/benchmark.rb:12:in `block in ms'
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/benchmark.rb:296:in `realtime'
activesupport (4.2.5.1) lib/active_support/core_ext/benchmark.rb:12:in `ms'
actionpack (4.2.5.1) lib/action_controller/metal/instrumentation.rb:44:in `block in render'
actionpack (4.2.5.1) lib/action_controller/metal/instrumentation.rb:87:in `cleanup_view_runtime'
activerecord (4.2.5.1) lib/active_record/railties/controller_runtime.rb:25:in `cleanup_view_runtime'
actionpack (4.2.5.1) lib/action_controller/metal/instrumentation.rb:43:in `render'
actionpack (4.2.5.1) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (4.2.5.1) lib/action_controller/metal/implicit_render.rb:5:in `send_action'
actionpack (4.2.5.1) lib/abstract_controller/base.rb:198:in `process_action'
actionpack (4.2.5.1) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (4.2.5.1) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
activesupport (4.2.5.1) lib/active_support/callbacks.rb:117:in `call'
activesupport (4.2.5.1) lib/active_support/callbacks.rb:117:in `call'
activesupport (4.2.5.1) lib/active_support/callbacks.rb:555:in `block (2 levels) in compile'
activesupport (4.2.5.1) lib/active_support/callbacks.rb:505:in `call'
activesupport (4.2.5.1) lib/active_support/callbacks.rb:505:in `call'
activesupport (4.2.5.1) lib/active_support/callbacks.rb:92:in `__run_callbacks__'
activesupport (4.2.5.1) lib/active_support/callbacks.rb:778:in `_run_process_action_callbacks'
activesupport (4.2.5.1) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.5.1) lib/abstract_controller/callbacks.rb:19:in `process_action'
actionpack (4.2.5.1) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (4.2.5.1) lib/action_controller/metal/instrumentation.rb:32:in `block in process_action'
activesupport (4.2.5.1) lib/active_support/notifications.rb:164:in `block in instrument'
activesupport (4.2.5.1) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (4.2.5.1) lib/active_support/notifications.rb:164:in `instrument'
actionpack (4.2.5.1) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
actionpack (4.2.5.1) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
activerecord (4.2.5.1) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (4.2.5.1) lib/abstract_controller/base.rb:137:in `process'
actionview (4.2.5.1) lib/action_view/rendering.rb:30:in `process'
actionpack (4.2.5.1) lib/action_controller/metal.rb:196:in `dispatch'
actionpack (4.2.5.1) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.2.5.1) lib/action_controller/metal.rb:237:in `block in action'
actionpack (4.2.5.1) lib/action_dispatch/routing/route_set.rb:74:in `call'
actionpack (4.2.5.1) lib/action_dispatch/routing/route_set.rb:74:in `dispatch'
actionpack (4.2.5.1) lib/action_dispatch/routing/route_set.rb:43:in `serve'
actionpack (4.2.5.1) lib/action_dispatch/journey/router.rb:43:in `block in serve'
actionpack (4.2.5.1) lib/action_dispatch/journey/router.rb:30:in `each'
actionpack (4.2.5.1) lib/action_dispatch/journey/router.rb:30:in `serve'
actionpack (4.2.5.1) lib/action_dispatch/routing/route_set.rb:815:in `call'
rack (1.6.4) lib/rack/etag.rb:24:in `call'
rack (1.6.4) lib/rack/conditionalget.rb:25:in `call'
rack (1.6.4) lib/rack/head.rb:13:in `call'
actionpack (4.2.5.1) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.2.5.1) lib/action_dispatch/middleware/flash.rb:260:in `call'
rack (1.6.4) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.6.4) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.2.5.1) lib/action_dispatch/middleware/cookies.rb:560:in `call'
activerecord (4.2.5.1) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.2.5.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:653:in `call'
activerecord (4.2.5.1) lib/active_record/migration.rb:377:in `call'
actionpack (4.2.5.1) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.2.5.1) lib/active_support/callbacks.rb:88:in `__run_callbacks__'
activesupport (4.2.5.1) lib/active_support/callbacks.rb:778:in `_run_call_callbacks'
activesupport (4.2.5.1) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (4.2.5.1) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.2.5.1) lib/action_dispatch/middleware/reloader.rb:73:in `call'
actionpack (4.2.5.1) lib/action_dispatch/middleware/remote_ip.rb:78:in `call'
actionpack (4.2.5.1) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
web-console (2.3.0) lib/web_console/middleware.rb:28:in `block in call'
web-console (2.3.0) lib/web_console/middleware.rb:18:in `catch'
web-console (2.3.0) lib/web_console/middleware.rb:18:in `call'
actionpack (4.2.5.1) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.2.5.1) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.2.5.1) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.2.5.1) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.2.5.1) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.2.5.1) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.2.5.1) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.2.5.1) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.6.4) lib/rack/methodoverride.rb:22:in `call'
rack (1.6.4) lib/rack/runtime.rb:18:in `call'
activesupport (4.2.5.1) lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
rack (1.6.4) lib/rack/lock.rb:17:in `call'
actionpack (4.2.5.1) lib/action_dispatch/middleware/static.rb:116:in `call'
rack (1.6.4) lib/rack/sendfile.rb:113:in `call'
railties (4.2.5.1) lib/rails/engine.rb:518:in `call'
railties (4.2.5.1) lib/rails/application.rb:165:in `call'
rack (1.6.4) lib/rack/lock.rb:17:in `call'
rack (1.6.4) lib/rack/content_length.rb:15:in `call'
rack (1.6.4) lib/rack/handler/webrick.rb:88:in `service'
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/webrick/httpserver.rb:138:in `service'
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/webrick/httpserver.rb:94:in `run'
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/webrick/server.rb:295:in `block in start_thread'
【问题讨论】：
粘贴路由和堆栈跟踪。 @ShamsulHaque 在编辑中添加了这些内容。<%= form_for(@steps) do |f| %> 这是你得到错误的地方.. 试试@step
【参考方案1】：
在控制器中：-
def new
@goal = Goal.find(params[:goal_id])
@step = @goal.steps.build
end
def edit
@goal = Goal.find(params[:goal_id])
end
def create
@goal = Goal.find(params[:goal_id])
@step = @goal.steps.new(step_params)
respond_to do |format|
if @step.save
format.html redirect_to goal_steps_path(@goal), notice: 'Step was successfully created.'
format.json render :show, status: :created, location: @step
else
format.html render :new
format.json render json: @step.errors, status: :unprocessable_entity
end
end
redirect_to(goal_steps_url(@goal))
end
def update
@goal = Goal.find(params[:goal_id])
@step.update(step_params)
respond_to do |format|
if @step.update(step_params)
format.html redirect_to goal_steps_path(@goal), notice: 'Step was successfully updated.'
format.json render :show, status: :ok, location: @step
else
format.html render :edit
format.json render json: @step.errors, status: :unprocessable_entity
end
end
end
形式：-
换行
<%= form_for(@steps) do |f| %>
与
<%= form_for[@goal,@step] do |f| %>
【讨论】：
它现在给我那个确切的行的错误“未定义的方法`steps_path'”。【参考方案2】：表单中的第一个参数不能包含 nil 或为空
首先，错误是由于您的表单具有@steps 而不是@step，而且您正在为嵌套资源创建一个表单，因此您的@987654323 @ 需要两个参数。以下更改应该让您继续前进
def new
@goal = Goal.find(params[:goal_id])
@step = @goal.steps.build
end
在形式上，改变
<%= form_for(@steps) do |f| %>
到
<%= form_for [@goal, @step] do |f| %>
【讨论】：
终于成功了！太感谢了，这几天郁闷了。真是一种解脱：D以上是关于尝试在 ruby on rails 中创建嵌套资源时，“表单中的第一个参数不能包含 nil 或为空”的主要内容，如果未能解决你的问题，请参考以下文章