我有一个用于模拟房屋的rails应用程序。 house包含rooms，并且会议室具有light和small_appliance的嵌套属性。我有一个calculator控制器，这是最终用户访问应用程序的方式。
我的问题是，我无法通过添加rooms从calculator正确呈现和提交。初始页面允许用户输入house信息，单击提交时使用save_house保存该信息。这也会将用户重定向到add_rooms页面，在那里他们可以为房子添加房间。
add_rooms显示正确，但是当我点击提交时，我收到此错误：
RuntimeError in Calculator#add_room
Showing app/views/calculator/add_rooms.html.erb where line #2 raised:
Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id
Extracted source (around line #2):
1: <div id="addRooms">
2: <p>House id is <%= @house.id %></p>
3:
4: <h3>Your rooms:</h3>
5: <% if @house.rooms %>
RAILS_ROOT: C:/Users/ryan/Downloads/react
Application Trace | Framework Trace | Full Trace
C:/Users/ryan/Downloads/react/app/views/calculator/add_rooms.html.erb:2:in `_run_erb_app47views47calculator47add_rooms46html46erb'
C:/Users/ryan/Downloads/react/app/controllers/calculator_controller.rb:36:in `add_room'
C:/Users/ryan/Downloads/react/app/controllers/calculator_controller.rb:33:in `add_room'
这对我来说很奇怪，因为当add_rooms首次渲染时，它会显示house_id。我不明白为什么在表单提交后没有通过。
以下是代码：
class Room < ActiveRecord::Base
# schema { name:string, house_id:integer }
belongs_to :house
has_many :lights, :dependent => :destroy
has_many :small_appliances, :dependent => :destroy
validates_presence_of :name
accepts_nested_attributes_for :lights, :reject_if => lambda { |a| a.values.all?(&:blank?) }, :allow_destroy => true
accepts_nested_attributes_for :small_appliances, :reject_if => lambda { |a| a.values.all?(&:blank?) }, :allow_destroy => true
end
class House < ActiveRecord::Base
has_many :rooms
# validation code not included
def add_room(room)
rooms << room
end
end
class CalculatorController < ApplicationController
def index
end
def save_house
@house = House.new(params[:house])
respond_to do |format|
if @house.save
format.html { render :action => 'add_rooms', :id => @house }
format.xml { render :xml => @house, :status => :created, :location => @house }
else
format.html { render :action => 'index' }
format.xml { render :xml => @house.errors, :status => :unprocessable_entity }
end
end
end
def add_rooms
@house = House.find(params[:id])
@rooms = Room.find_by_house_id(@house.id)
rescue ActiveRecord::RecordNotFound
logger.error("Attempt to access invalid house #{params[:id]}")
flash[:notice] = "You must create a house before adding rooms"
redirect_to :action => 'index'
end
def add_room
@room = Room.new(params[:room])
@house = @room.house
respond_to do |format|
if @room.save
flash[:notice] = "Room \"#...@room.name}\" was successfully added."
format.html { render :action => 'add_rooms' }
format.xml { render :xml => @room, :status => :created, :location => @room }
else
format.html { render :action => 'add_rooms' }
format.xml { render :xml => @room.errors, :status => :unprocessable_entity }
end
end
rescue ActiveRecord::RecordNotFound
logger.error("Attempt to access invalid house #{params[:id]}")
flash[:notice] = "You must create a house before adding a room"
redirect_to :action => 'index'
end
def report
flash[:notice] = nil
@house = House.find(params[:id])
@rooms = Room.find_by_house_id(@house.id)
rescue ActiveRecord::RecordNotFound
logger.error("Attempt to access invalid house #{params[:id]}")
flash[:notice] = "You must create a house before generating a report"
redirect_to :action => 'index'
end
end
<div id="addRooms">
<p>House id is <%= @house.id %></p>
<h3>Your rooms:</h3>
<% if @house.rooms %>
<ul>
<% for room in @house.rooms %>
<li>
<%= h room.name %> has <%= h room.number_of_bulbs %>
<%= h room.wattage_of_bulbs %> watt bulbs, in use for
<%= h room.usage_hours %> hours per day.
</li>
<% end %>
</ul>
<% else %>
<p>You have not added any rooms yet</p>
<% end %>
<%= render :partial => 'rooms/room_form' %>
<br />
</div>
<%= button_to "Continue to report", :action => "report", :id => @house %>
_room_ form.html.erb <% form_for :room, @house.rooms.build, :url => { :action => :add_room } do |form| %>
<%= form.error_messages %>
<p>
<%= form.label :name %><br />
<%= form.text_field :name %>
</p>
<h3>Lights</h3>
<% form.object.lights.build if form.object.lights.empty? %>
<% form.fields_for :lights do |light_form| %>
<%= render :partial => "light", :locals => { :form => light_form } %>
<% end %>
<p class="addLink"><%= add_child_link "[+] Add new light", form, :lights %></p>
<h3>Small Appliances</h3>
<% form.object.small_appliances.build if form.object.small_appliances.empty? %>
<% form.fields_for :small_appliances do |sm_appl_form| %>
<%= render :partial => "small_appliance", :locals => { :form => sm_appl_form } %>
<% end %>
<p class="addLink"><%= add_child_link "[+] Add new small appliance", form, :small_appliances %></p>
<p><%= form.submit "Submit" %></p>
<% end %>
module ApplicationHelper
def remove_child_link(name, form)
form.hidden_field(:_delete) + link_to_function(name, "remove_fields(this)")
end
def add_child_link(name, form, method)
fields = new_child_fields(form, method)
link_to_function(name, h("insert_fields(this, \"#{method}\", \"#{escape_javascript(fields)}\")"))
end
def new_child_fields(form_builder, method, options = {})
options[:object] ||= form_builder.object.class.reflect_on_association(method).klass.new
options[:partial] ||= method.to_s.singularize
options[:form_builder_local] ||= :form
form_builder.fields_for(method, options[:object], :child_index => "new_#{method}") do |form|
render(:partial => options[:partial], :locals => { options[:form_builder_local] => form })
end
end
end
谢谢，
瑞恩
答案 0 :(得分：2)
出于好奇，为什么不让房子接受房间的嵌套属性。这将使您的控制器代码更简单，因为添加许多房间，灯光和小型设备就像做@ house.update_attributes（params [：house]）一样简单。然而，这不是一个有帮助的答案，因为如果你做了改变，你仍然会遇到当前的问题。
您的第一个错误来自第一行 app / views / calculator / _room_form.html.erb
<% form_for :room, :url => { :action => :add_room, :id => @house } do |form| %>
你没有给form_for一个对象，所以add_child调用new_child_fields方法 _link试图在Nil类上调用reflect_on_association。
解决方案是将行更改为
<% form_for :room, @house.rooms.build, :url => { :action => :add_room } do |form| %>
这使您可以简化控制器，因为与房屋相关联的房间已经传递给它。
def add_room
@room = Room.new(params[:room])
@house = @room.house
respond_to do |format|
if @room.save
flash[:notice] = "Room \"#...@room.name}\" was successfully added."
format.html { render :action => 'add_rooms' }
format.xml { render :xml => @room, :status => :created, :location => @room }
else
format.html { render :action => 'add_rooms' }
format.xml { render :xml => @room.errors, :status => :unprocessable_entity }
end
end
rescue ActiveRecord::RecordNotFound
logger.error("Attempt to access invalid house #{params[:id]}")
flash[:notice] = "You must create a house before adding a room"
redirect_to :action => 'index'
end
我相信你的第二个错误是同样的问题。但是因为您正在调用has_many访问器而不是生成nil，所以您传递的是一个空数组，这解释了错误消息的不同之处。同样，解决方案是在渲染之前构建一个轻型和小型设备（如果还不存在）。
<h3>Lights</h3>
<% form.object.lights.build if form.object.lights.empty? %>
<% form.fields_for :lights do |light_form| %>
<%= render :partial => 'rooms/light', :locals => { :form => light_form } %>
<% end %>
<p class="addLink"><%= add_child_link "[+] Add new light", form, :lights %></p>
<h3>Small Appliances</h3>
<% form.object.small_appliances.build if form.object.small_appliances.empty? %>
<% form.fields_for :small_appliances do |sm_appl_form| %>
<%= render :partial => 'rooms/small_appliance', :locals => { :form => sm_appl_form } %>
<% end %>
您的新错误来自：
def new_child_fields(form_builder, method, options = {})
options[:object] ||= form_builder.object.class.reflect_on_association(method).klass.new
# specifically this line.
options[:partial] ||= method.to_s.singularize
options[:form_builder_local] ||= :form
form_builder.fields_for(method, options[:object], :child_index => "new_#{method}") do |form|
render(:partial => options[:partial], :locals => { options[:form_builder_local] => form })
end
end
new_child_fields假设_light部分位于app / views / calculators文件夹中
解决方案是将light和small_appliances部分移动到此文件夹，或修改辅助方法以接受部分选项。