我有一個包含 3 個模型的投票應用程式。
民意調查.rb
class poll < ApplicationRecord
validates_presence_of :user, :title
belongs_to :user
has_many :questions, dependent: :destroy
has_many :options, through: :questions
accepts_nested_attributes_for :questions
end
問題.rb
class Question < ApplicationRecord
validates_presence_of :poll_id, :question_id, :title
belongs_to :poll
has_many :options
accepts_nested_attributes_for :options, reject_if: proc { |attributes| attributes['title'].blank? }
end
選項.rb
class Option < ApplicationRecord
validates_presence_of :question_id, :title
belongs_to :question
belongs_to :poll
end
我希望問題表單有一個用于添加選項的欄位，因此我已將其添加到問題_form 中。
<%= form.fields_for :option do |o| %>
<div>
<%= o.label "Option", style: "display: block" %>
<%= o.text_field :title, placeholder: "Enter Option here" %>
</div>
<% end %>
我現在可以看到一個很好的選項塊。雖然我希望有 3 個可能的選項，但在 questions_controller.rb 中我添加了以下內容：
def new
@question = @poll.questions.build
3.times { @question.options.build } # 3 different options
end
盡管如此，我只看到一個選項塊而不是 3 個。為什么會出現這種情況，我該如何解決？此外，我沒有看到選項 postgresql 表中的新條目。
完整問題_controller.rb
class QuestionsController < ApplicationController
before_action :set_question, only: %i[ show edit update destroy ]
before_action :set_poll
# GET /questions or /questions.json
def index
@questions = Question.all
end
# GET /questions/1 or /questions/1.json
def show
end
# GET /questions/new
def new
# @question = Question.new
@question = @poll.questions.build
3.times { @question.options.build } # 5 different options
end
# GET /questions/1/edit
def edit
end
# POST /questions or /questions.json
def create
@question = Question.new(question_params)
respond_to do |format|
if @question.save
format.html { redirect_to polls_question_url(@question), notice: "Question was successfully created." }
format.json { render :show, status: :created, location: @question }
else
format.html { render :new, status: :unprocessable_entity }
format.json { render json: @question.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /questions/1 or /questions/1.json
def update
respond_to do |format|
if @question.update(question_params)
format.html { redirect_to polls_question_url(@question), notice: "Question was successfully updated." }
format.json { render :show, status: :ok, location: @question }
else
format.html { render :edit, status: :unprocessable_entity }
format.json { render json: @question.errors, status: :unprocessable_entity }
end
end
end
# DELETE /questions/1 or /questions/1.json
def destroy
poll_id = Question.find_by(params[:poll_id])
session[:return_to] ||= request.referer
@question.destroy
respond_to do |format|
format.html { redirect_to session.delete(:return_to), notice: "Question was successfully destroyed." }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_question
@question = Question.find(params[:id])
end
# Only allow a list of trusted parameters through.
def question_params
params.require(:question).permit(:poll_id, :question_type, :title, :description, :randomize_selection, :voter_abstain, { option_attributes: [:question_id, :poll_id, :party_id, :title, :description] } )
end
def set_poll
@poll = poll.find_by(params[:poll_id])
end
end
路線.rb
resources :users do
resources :polls
end
resource :polls do
resources :questions
end
resource :questions do
resources :options
end
編輯：
這是我的部分問題。
_form.html.erb
<%= form_with(model: [@Poll, question] ) do |form| %>
<% if question.errors.any? %>
<div style="color: red">
<h2><%= pluralize(question.errors.count, "error") %> prohibited this question from being saved:</h2>
<ul>
<% question.errors.each do |error| %>
<li><%= error.full_message %></li>
<% end %>
</ul>
</div>
<% end %>
<div>
<%= form.hidden_field :poll_id %>
</div>
<div>
<%= form.label :question_type, style: "display: block" %>
<%= form.text_field :question_type %>
</div>
<div>
<%= form.label :title, style: "display: block" %>
<%= form.text_field :title %>
</div>
<div>
<%= form.label :description, style: "display: block" %>
<%= form.text_area :description %>
</div>
<div>
<%= form.label :randomize_selection, style: "display: block" %>
<%= form.check_box :randomize_selection %>
</div>
<div>
<%= form.label :voter_abstain, style: "display: block" %>
<%= form.check_box :voter_abstain %>
</div>
<div>
<%= form.fields_for :options do |o| %>
<div>
<%= o.label "Option", style: "display: block" %>
<%= o.text_field :title, placeholder: "Enter Option here" %>
</div>
<% end %>
</div>
<div>
<%= form.submit %>
</div>
<% end %>
這是我正在渲染表格的民意調查顯示。
顯示.html.erb
<p style="color: green"><%= notice %></p>
<p>
<strong>Poll Title:</strong>
<%= @poll.title %>
<%= render @poll %>
</p>
<div>
<%= link_to "Edit this poll", edit_user_poll_path(@poll) %> |
<%= link_to "Back to polls", user_polls_path %> |
<%= link_to "Destroy this poll", user_poll_path(@poll), method: :delete %>
</div>
<% if @poll.questions.any? %>
<hr>
<h2>Questions:</h2>
<%= render @poll.questions %>
<% end %>
<hr>
<h2>Add a new Question:</h2>
<%= render "questions/form", question: @poll.questions.build %>
uj5u.com熱心網友回復：
您傳遞給的引數必須fields_for與模型上的關聯名稱匹配：
<%= form.fields_for :options do |o| %>
<div>
<%= o.label "Option", style: "display: block" %>
<%= o.text_field :title, placeholder: "Enter Option here" %>
</div>
<% end %>
非常注意 Rails 中的復數。它是讓約定優于配置為您作業而不是對您不利的重要部分。
但是，此代碼還有很多其他問題。
- 常量應該始終是
CamelCase或UPPERCASE在 Ruby 中 - 您需要更改class poll并class Poll修復對類的所有參考。這不僅僅是風格問題，因為解釋器對以大寫字母開頭的識別符號的處理方式完全不同。 - 你沒有正確嵌套它。您有一個嵌套路由，但您仍然將其視為控制器和檔案字串中的非嵌套資源。
- 您正在引數白名單中傳遞父 ID。
:poll_id并且:question_id不應該被列入白名單。不要通過隱藏輸入傳遞父 ID。問題 id 是由 Rails 分配的——你不應該相信用戶會通過它。 - 該選項不需要
poll_id. 使用間接has_one關聯上樹。這可能會導致問題及其選項屬于不同民意調查的邊緣情況。
首先讓我們修復模型：
class Poll < ApplicationRecord
# belongs_to assocations are required by default
# adding validations will just cause duplicate error messages
validates_presence_of :title
belongs_to :user
has_many :questions, dependent: :destroy
has_many :options, through: :questions
accepts_nested_attributes_for :questions
end
class Question < ApplicationRecord
validates_presence_of :title
belongs_to :poll
has_many :options
accepts_nested_attributes_for :options, reject_if: proc { |attributes| attributes['title'].blank? }
end
class Option < ApplicationRecord
validates_presence_of :title
belongs_to :question
has_one :poll, through: :question
end
那我建議你使用淺嵌套
resource :polls do
resources :questions, shallow: true
end
這將創建沒有前綴的問題成員路由（顯示、編輯、洗掉），而集合路由（索引、創建、新建）是嵌套的。/polls/:poll_id
并且您將控制器設定為：
class QuestionsController < ApplicationController
before_action :set_question, only: %i[ show edit update destroy ]
before_action :set_poll, only: %i[ new create index ]
# GET /polls/1/questions or /polls/1/questions.json
def index
@questions = @poll.questions.all
end
# GET /questions/1 or /polls/1/questions/1.json
def show
end
# GET /polls/1/questions/new
def new
# build is just an alias of new for legacy compatibility with Rails 2...
# its about time that we ditch it
@question = @poll.questions.new
3.times { @question.options.new } # 5 different options
end
# GET /questions/1/edit
def edit
end
# POST /polls/1/questions or /polls/1/questions.json
def create
@question = @poll.questions.new(question_params)
respond_to do |format|
if @question.save
format.html { redirect_to @question, notice: "Question was successfully created." }
format.json { render :show, status: :created, location: @question }
else
format.html { render :new, status: :unprocessable_entity }
format.json { render json: @question.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /questions/1 or /questions/1.json
def update
respond_to do |format|
if @question.update(question_params)
format.html { redirect_to @question, notice: "Question was successfully updated." }
format.json { render :show, status: :ok, location: @question }
else
format.html { render :edit, status: :unprocessable_entity }
format.json { render json: @question.errors, status: :unprocessable_entity }
end
end
end
# DELETE /questions/1 or /questions/2.json
def destroy
session[:return_to] ||= request.referer
@question.destroy
respond_to do |format|
format.html { redirect_to session.delete(:return_to), notice: "Question was successfully destroyed." }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_question
@question = Questions.find(params[:id])
end
# Only allow a list of trusted parameters through.
def question_params
# do not write this in a single unreadable line
params.require(:question).permit(
:question_type,
:title,
:description,
:randomize_selection,
:voter_abstain,
# do not wrap hash arguments in brackets
# as it will break if/when the `permit` method is changed to use real keyword arguments
# for has_many assocations the key naming convention is also plural_attributes
options_attributes: [
:party_id,
:title,
:description
]
)
end
def set_poll
@poll = Poll.find_by(params[:poll_id])
end
end
這里的主要區別在于，您應該通過嵌套路由的 URL 中的引數查找輪詢，并從輪詢實體（設定poll_id）中創建問題。
添加：
您實際上并沒有使用您在控制器中初始化的模型。如果你想從一個完全不同的動作呈現表單，你需要在那里初始化實體變數：
class PollsController < ApplicationController
def show
@question = @poll.questions.new
3.times { @question.options.new } # 5 different options ???
end
# ...
end
<%= render "questions/form", question: @question %>
在你的部分中，你有一個鬼鬼祟祟的小蟲子。Ruby 區分大小寫，因此@poll實際上@Poll是不同的變數。
irb(main):049:0> @foo = "bar" => "bar"
irb(main):050:0> @Foo
=> nil
由于實體變數是自動激活的，因此您只會得到意外的 nil 而不是錯誤。你真正想要的是：
<%= form_with(model: [@poll, question] ) do |form| %>
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