ActionController::ParameterMissing with custom rou

问题:

I am building a digital library, and right now I am currently trying to add soft_delete to an application, but I am having issues with the error showing

ActionController::ParameterMissing in BooksController#update
param is missing or the value is empty: book

The action of the soft_delete method is to update its table in the database from its default false value to true. I have checked through my code but I cannot find where the issue is from.

Books Model

class Book < ApplicationRecord
  #add a model scope to fetch only non-deleted records
  scope :not_deleted, -> { where(soft_deleted: false) }
  scope :deleted, -> { where(soft_deleted: true) }

  #create the soft delete method
  def soft_delete 
    update(soft_deleted: true)
    soft_deleted
  end

  # make an undelete method
  def undelete
    update(soft_deleted: false)
  end
end

Books Controller (Truncated)

class BooksController < ApplicationController
  before_action :set_book, only: [:show, :edit, :update, :soft_delete, :destroy]

  def index
    @books = Book.not_deleted
  end

...

  def destroy
    @book.destroy
    respond_to do |format|
      format.html { redirect_to books_url, notice: 'Book was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  def soft_delete
    respond_to do |format|
      @book.soft_delete(book_params)
        format.html { redirect_to books_url, notice: 'Book was successfully deleted.' }
        format.json { head :no_content }
    end
  end



  private
    # Use callbacks to share common setup or constraints between actions.
    def set_book
      @book = Book.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def book_params
      params.require(:book).permit(:name, :author, :description, :soft_deleted)
    end
end

Route

Rails.application.routes.draw do
  resources :books
  put '/books/:id' => 'books#soft_delete'
end

Books Index View

<h1>Books</h1>
<tbody>
    <% @books.each do |book| %>
      <tr>
        <td><%= book.name %></td>
        <td><%= book.author %></td>
        <td><%= book.description %></td>
        <td><%= link_to 'Show', book %></td>
        <td><%= link_to 'Edit', edit_book_path(book) %></td>
        <td><%= link_to 'Destroy', book, method: :delete, data: { confirm: 'Are you sure?' } %></td>
        <td><%= link_to 'Soft Delete', book, method: :put, data: { confirm: 'Are you sure?' } %></td>
        soft_delete
      </tr>
    <% end %>
  </tbody>

回答1:

I suggest you not use explicit routes like put '/books/:id' => 'books#soft_delete' Rails has 'member routes', so you can rewrite your routes such way:

resources :books, only: %i[index destroy] do
  member { put :soft_delete }
end

Here i've used option 'only' which allows you to define only necessary routes for you (not all 7, but 2 - index and destroy)

Firstly: you've defined resources :books. This definition creates 7 routes for you:

    books GET    /books(.:format)           -> books#index
          POST   /books(.:format)           -> books#create
 new_book GET    /books/new(.:format)       -> books#new
edit_book GET    /books/:id/edit(.:format)  -> books#edit
     book GET    /books/:id(.:format)       -> books#show
          PATCH  /books/:id(.:format)       -> books#update (this and next route are the same, and considering as 1, so we have 7 routes, not 8)
          PUT    /books/:id(.:format)       -> books#update
          DELETE /books/:id(.:format)       -> books#destroy

So route with method PUT and path '/books/:id' already present and your put '/books/:id' => 'books#soft_delete' will never be used. That is what triggered error: 'ActionController::ParameterMissing in BooksController#update ' - your link click has triggered BooksController#update action call, which requires book key in the params.

Secondly: I suggest you to remove methods :soft_delete and :undelete from model. Rails provide methods :toggle! for instant writing to the DB and :toggle for changing value and not saving changes immediately . So you can write right in the controller such code:

book = Book.find_by(id: params[:id])
book.toggle!(:soft_deleted)

Note that column soft_deleted should be boolean to make that work.

your link shall be such:

link_to 'Soft Delete', soft_delete_book_path(book), data: { method: :put }

回答2:

Rails is routing <%= link_to 'Soft Delete', book, method: :put...%> to the update action because resource :books is defined before your custom route, and Rails use the first one matching the request.

Run rails routes -g books in a terminal and you'll see something like:

    books GET    /books(.:format)          books#index
          POST   /books(.:format)          books#create
 new_book GET    /books/new(.:format)      books#new
edit_book GET    /books/:id/edit(.:format) books#edit
     book GET    /books/:id(.:format)      books#show
          PATCH  /books/:id(.:format)      books#update
          PUT    /books/:id(.:format)      books#update
          DELETE /books/:id(.:format)      books#destroy
          PUT    /books/:id(.:format)      books#soft_delete

As you can see, the routes for books#update and books#soft_delete are identical.

You can fix it by creating a named route: put '/books/:id' => 'books#soft_delete', as: 'soft_delete':

      books GET    /books(.:format)          books#index
            POST   /books(.:format)          books#create
   new_book GET    /books/new(.:format)      books#new
  edit_book GET    /books/:id/edit(.:format) books#edit
       book GET    /books/:id(.:format)      books#show
            PATCH  /books/:id(.:format)      books#update
            PUT    /books/:id(.:format)      books#update
            DELETE /books/:id(.:format)      books#destroy
soft_delete PUT    /books/:id(.:format)      books#soft_delete

Then, modify your template to use the new helper: <%= link_to 'Soft Delete', soft_delete_path(book), method: :put...%>