Question

我有书籍，章节嵌套在下面，章节中嵌套的每一章都有问题，而问题中嵌套了评论。

当我点击书籍页面上的新章节时，如何将其保存到与其相关联的书籍中，以及如何获取书籍#show page以遍历所有章节标题（包含每章的链接）显示页面。）

这是错误：未定义的方法`title＆＃39;为零：NilClass。参考此文件：Users / bardiap / saasapp / app / views / books / show.html.erb

<div class="homepage">

<h1><%= @book.title %></h1>

<%= link_to 'New chapter', new_book_chapter_path(@book, @chapter) %>

<% @chapters.each do |chapter| %>
            <h3><%= link_to chapter.title, chapter %></h3>
        <% end %>

<p>
<%= link_to 'Edit', edit_book_path(@book) %> |
<%= link_to 'Destroy', book_path(@book),
          method: :delete,
          data: { confirm: 'Are you sure?' } %> |
<%= link_to 'Back', books_path %> |
</p>

</div>

这是我的书籍和章节控制器：

class BooksController < ApplicationController
  def show
    @book = Book.find(params[:id])
    @chapters = Chapter.where(book_id: @book.id).order("created_at ASC")
  end

  def index
    @books = Book.all
  end

  def new
    @book = Book.new
  end

  def edit
    @book = Book.find(params[:id])
  end

  def create
    @book =  Book.new(book_params)

    if @book.save
      redirect_to @book
    else
      render 'new'
    end
  end

  def update
    @book = Book.find(params[:id])

    if @book.update(book_params)
      redirect_to @book
    else
    render 'edit'
  end
end

  def destroy
    @book = Book.find(params[:id])
    @book.destroy

    redirect_to books_path
  end

  private
    def book_params
      params.require(:book).permit(:title,:text,:author)
    end
  end

章

def show
    @chapter = Chapter.find(params[:id])
    @questions = question.where(chapter_id: @chapter.id).order("created_at ASC")
  end

  def index
    @chapters = Chapter.all
  end

  def new
    @chapter = Chapter.new
  end

  def edit
    @chapter = Chapter.find(params[:id])
  end

  def create
    @chapter = Chapter.new(chapter_params)

    if @chapter.save
      render 'books/show'
    else
      render 'books/show'
    end
  end

  def update
    @chapter = Chapter.find(params[:id])

    if @chapter.update(chapter_params)
      redirect_to @chapter
    else
      render 'edit'
  end
end

  def destroy
    @chapter = Chapter.find(params[:id])
    @chapter.destroy

    redirect_to chapters_path
  end

  private
    def chapter_params
      params.require(:chapter).permit(:title, :text)
    end
  end

以下是模型和路线

class Book < ApplicationRecord
  has_many :chapters
  validates :title, presence: true,
                    length:{minimum: 5}
end

class Chapter < ApplicationRecord
  has_many :questions
  belongs_to :book
  validates :title, presence: true,
                    length:{minimum: 5}
end

路线

Rails.application.routes.draw do
  devise_for :users
  root to: 'pages#home'
  get 'about', to: 'pages#about'
  get 'terms', to: 'pages#terms'
  get 'privacy', to: 'pages#privacy'

  resources :contacts, only: :create
  resources :podcasts
  resources :books do
    resources :chapters, shallow: true
  end
  resources :chapters do
    resources :questions, shallow: true
  end
  resources :questions do
    resources :comments, module: :questions, shallow: true
  end
  resources :users do
    resource :profile
    resources :comments
  end
  get 'contact-us', to: 'contacts#new', as: 'new_contact'
  get 'podcast', to: 'pages#podcast'
  resources :essays do
    resources :comments, module: :essays, shallow: true
  end
end

观点：

章节/ _form.html.erb

<%= form_for [@book, @chapter] do |form| %>
  <p>
    <%= form.label :title %><br>
    <%= form.text_field :title %>
  </p>
  <p>
    <%= form.label :text %><br>
    <%= form.text_area :text %>
  </p>
  <p>
    <%= form.submit "Submit" %>
  </p>
<% end %>

章节/ index.html.erb

<div class="homepage">



  <button class="mdl-button mdl-js-button mdl-button--fab mdl-button--mini-fab">
    <i class="material-icons"><%= link_to "add", new_chapter_path%></i>
  </button>

<div class="mdl-grid">
<% @chapters.each do |chapter| %>
  <div class="mdl-cell mdl-cell--4-col">
    <div class="demo-card-event mdl-card mdl-shadow--2dp">
      <div class="mdl-card__title mdl-card--expand">
        <h4>
          <%=chapter.title%>
        </h4>
      </div>
      <div class="mdl-card__actions mdl-card--border">
          <%=link_to 'VIEW BOOK',chapter_path(chapter), class: "mdl-button mdl-button--colored mdl-js-button mdl-js-ripple-effect"%>
        <div class="mdl-layout-spacer"></div>
        <i class="material-icons">chapter</i>
      </div>
    </div>
  </div>
<% end %>
</div>

<% @chapters.each do |chapter| %>

<%= link_to 'Edit', edit_chapter_path(chapter) %> |
<%= link_to 'Destroy', chapter_path(chapter),
          method: :delete,
          data: { confirm: 'Are you sure?' } %>
<% end %>

<br><br><br><br><br>

</div>

章节/ show.html.erb

<div class="homepage">


<h3><%= @chapter.title %></h3>
<h5><%= @chapter.text %></h5>



<p>
<%= link_to 'Edit', edit_book_path(@book) %> |
<%= link_to 'Destroy', book_path(@book),
          method: :delete,
          data: { confirm: 'Are you sure?' } %> |
<%= link_to 'Back', books_path %> |
</p>

</div>

我哪里出错了，还有其他方法可以让我的代码更好用。

Answer 1

在图书/ show：

中创建图书中的新章节

<%= link_to 'New chapter', new_book_chapter_path(@book) %>

（无需传递章节，因为它将被创建）。然后，在ChaptersController中#new：

def new
  @book = Book.find_by(id: params[:book_id]
  if @book
    @chapter = @book.chapters.build
  end
end

您还可以更改BooksController＃show

def show
  @book = Book.find_by(id: params[:id])
  if @book
    @chapters = @book.chapters.order("created_at ASC")
  end
end

继续在章节#create中获取NoMethodError

1 个答案: