ruby-on-rails - 使用单个 form_with 在 Rails 中创建和编辑嵌套资源

Question

背景

在我的应用程序中，系列 由许多书籍 组成。系列的显示页面允许用户查看系列中的所有书籍并使用表单向系列中添加新书。

显示 页面上列出的每本书都有指向该书的编辑 页面的链接。编辑页面包含用于最初添加图书的相同表单。编辑图书时，表格应自动填写图书现有信息。

问题

如何配置我的 form_with标记以便它既可以创建新书又可以编辑现有书(自动填写编辑表单)？我尝试了以下配置，但它们要么破坏了编辑页面，要么破坏了显示页面:

1. <%= form_with(model: [ @series, @series.books.build ], local: true) do |form| %>
   • 打破图书编辑页面
   • 错误:没有错误，但表单不会自动填充数据
2. <%= form_with(model: @book, url: series_book_path, local: true) do |form| %>
   • 休息系列显示页面
   • 错误:No route matches {:action=>"show", :controller=>"books", :id=>"6"}, missing required keys: [series_id]
3. <%= form_with(model: [:series, @book], local: true) do |form| %>
   • 休息系列显示页面
   • 错误:Undefined method 'model_name' for nil:NilClass
4. <%= form_with(model: [@series, @series.books.find(@book.id)], local: true) do |form| %>
   • 休息系列显示页面
   • 错误:undefined method 'id' for nil:NilClass
5. <%= form_with(model: @book, url: [@series, @book], local: true) do |form| %>
   • 在系列显示页面上提交新书时中断
   • 错误:No route matches [POST] "/series/6"

我查阅过的资源:

• https://api.rubyonrails.org/v5.2.2/classes/ActionView/Helpers/FormHelper.html#method-i-form_with
• https://guides.rubyonrails.org/form_helpers.html
• https://guides.rubyonrails.org/routing.html#resource-routing-the-rails-default
• https://github.com/rails/rails/blob/master/actionview/lib/action_view/helpers/form_helper.rb

现有代码

下面是相关代码的精简部分，以及指向它们在我当前 GitHub 存储库中的位置的链接。

config/routes.rb

resources :series do
  resources :books
end

app/models/book.rb

class Book < ApplicationRecord
  belongs_to :series
end

app/models/series.rb

class Series < ApplicationRecord
  has_many :books, dependent: :destroy
end

db/schema.rb

create_table "books", force: :cascade do |t|
  t.integer "series_number"
  t.integer "year_published"
  t.integer "series_id"
  t.datetime "created_at", null: false
  t.datetime "updated_at", null: false
  t.index ["series_id"], name: "index_books_on_series_id"
end

create_table "series", force: :cascade do |t|
  t.string "title"
  t.datetime "created_at", null: false
  t.datetime "updated_at", null: false
end

app/views/series/show.html.erb

<%= render @series.books %>
<%= render 'books/form' %>

app/views/books/_book.html.erb

<%= link_to 'Edit', edit_series_book_path(book.series, book) %>

app/views/books/edit.html.erb

<%= render 'form' %>

app/views/books/_form.html.erb

<%= form_with(model: @book, url: [@series, @book], local: true) do |form| %>
  <%= form.label :series_number %>
  <%= form.number_field :series_number %>

  <%= form.label :year_published %>
  <%= form.number_field :year_published %>
<% end %>

app/controllers/books_controller.rb

class BooksController < ApplicationController
  def index
    @books = Book.all
  end

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

  def new
    @book = Book.new
  end

  def edit
    @series = Series.find(params[:series_id])
    @book = @series.books.find(params[:id])
  end

  def create
    @series = Series.find(params[:series_id])
    @book = @series.books.create(book_params)
    redirect_to series_path(@series)
  end

  def destroy
    @series = Series.find(params[:series_id])
    @book = @series.books.find(params[:id])
    @book.destroy
    redirect_to series_path(@series)
  end

  private
    def book_params
      params.require(:book).permit(:year_published, :series_number)
    end
end

路线

          Prefix Verb   URI Pattern                                 Controller#Action
        articles GET    /articles(.:format)                         articles#index
                 POST   /articles(.:format)                         articles#create
     new_article GET    /articles/new(.:format)                     articles#new
    edit_article GET    /articles/:id/edit(.:format)                articles#edit
         article GET    /articles/:id(.:format)                     articles#show
                 PATCH  /articles/:id(.:format)                     articles#update
                 PUT    /articles/:id(.:format)                     articles#update
                 DELETE /articles/:id(.:format)                     articles#destroy
    series_books GET    /series/:series_id/books(.:format)          books#index
                 POST   /series/:series_id/books(.:format)          books#create
 new_series_book GET    /series/:series_id/books/new(.:format)      books#new
edit_series_book GET    /series/:series_id/books/:id/edit(.:format) books#edit
     series_book GET    /series/:series_id/books/:id(.:format)      books#show
                 PATCH  /series/:series_id/books/:id(.:format)      books#update
                 PUT    /series/:series_id/books/:id(.:format)      books#update
                 DELETE /series/:series_id/books/:id(.:format)      books#destroy
    series_index GET    /series(.:format)                           series#index
                 POST   /series(.:format)                           series#create
      new_series GET    /series/new(.:format)                       series#new
     edit_series GET    /series/:id/edit(.:format)                  series#edit
          series GET    /series/:id(.:format)                       series#show
                 PATCH  /series/:id(.:format)                       series#update
                 PUT    /series/:id(.:format)                       series#update
                 DELETE /series/:id(.:format)                       series#destroy

Answer 1

您可以将数组传递给表单以处理嵌套和“浅”路由:

<%= form_with(model: [@series, @book], local: true) do |form| %>

<% end %>

Rails 压缩数组(删除 nil 值)，因此如果 @series 为 nil，表单将返回到 book_url(@book) 或 books_url。但是，您需要从 Controller 正确处理设置 @series 和 @book。

class SeriesController < ApplicationController
  def show
    @series = Series.find(params[:id])
    @book = @series.books.new # used by the form
  end
end

您可以使用 local 在您的 View 中处理此问题变量:

# app/views/books/_form.html.erb
<%= form_with(model: model, local: true) do |form| %>

<% end %>

# app/views/books/edit.html.erb
<%= render 'form', locals: { model: [@series, @book] } %>

# app/views/series/show.html.erb
<%= render 'books/form', locals: { model: [@series, @series.book.new] } %>

您还可以使用 shallow: true避免嵌套成员路由的选项(显示、编辑、更新、销毁):

resources :series do
  resources :books, shallow: true
end

这会让你做到:

# app/views/books/edit.html.erb
<%= render 'form', model: @book %>

# app/views/books/_book.html.erb
<%= link_to 'Edit', edit_book_path(book) %>