Question

我正在尝试按照本教程。它已在Rails的早期版本中编写，我正在使用Rails 4.在“为新方法创建视图文件”一节中，我更新了给定的代码示例以使用当前的Rails但我收到以下错误：

ActiveRecord::RecordInvalid in BookController#create
Validation failed: Title can't be blank, Price Error Message

    Extracted source (around line #14):
    12 def create
    13    @book = Book.new(book_params)
    14    if @book.save!
    15      redirect_to :action => 'list'
    16    else
    17      @subjects = Subject.all

    Rails.root: C:/Ruby193/mylibrary

    Application Trace | Framework Trace | Full Trace
    app/controllers/book_controller.rb:14:in `create'
    Request

    Parameters:

    {"utf8"=>"✓",
     "authenticity_token"=>"Xla1xJlMqCx96ZITbI6JHOvoNIoAHc5ItcZgcMzs0/Y=",
     "title"=>"asd",
     "price"=>"asd",
     "book"=>{"subject_id"=>"1"},
     "description"=>"asd",
     "commit"=>"Create",
     "method"=>"post"}

这是我的路由文件：

Rails.application.routes.draw do
get 'book/list' => 'book#list'
get 'book/new' => 'book#new'
post 'book/create' => 'book#create'
end

这是我的控制器类：

class BookController < ApplicationController
  def list
    @books = Book.all
  end
  def show
    @book = Book.find(params[:id])
  end
  def new
    @book = Book.new
    @subjects = Subject.all
  end
  def create
    @book = Book.new(book_params)
    if @book.save!
      redirect_to :action => 'list'
    else
      @subjects = Subject.all
      render :action => 'new'
    end
  end
  def edit
    @book = Book.find(params[:id])
    @subjects = Subject.all
  end
  def update
    @book = Book.find(params[:id])
    if @book.update_attributes(book_params)
      redirect_to :action => 'show', :id => @book
    else
      @subjects = Subject.all
      render :action => 'edit'
    end
  end
  def delete
    Book.find(params[:id]).destroy
    redirect_to :action => 'list'
  end

  private

  def book_params
    params.require(:book).permit(:title, :price, :description)
  end

end

这是view- new.html

<h1>Add new book</h1>
<%= form_tag(controller: "book", action: "create", method: "post") do %>

    <%= label_tag(:title, "Title") %>
    <%= text_field_tag(:title) %><br>
    <%= label_tag(:price, "Price") %>
    <%= text_field_tag(:price) %><br>
    <%= label_tag(:q, "Subject") %>
    <%= collection_select(:book,:subject_id,@subjects,:id,:name) %><br>a
    <%= label_tag(:description, "Description") %><br>
    <%= text_area_tag(:description) %><br>
    <%= submit_tag( "Create") %>

<%end %>
<%= link_to 'Back', {:action => 'list'} %>

我该怎么办？提前谢谢

Answer 1

您需要更改表单，以便将：title属性正确放置在参数中的book键下方。还有其他助手可以让你这样做：

尝试更改以下行：

label_tag( :title )
text_field_tag(:title)

到

label( :book, :title )
text_field(:book, :title )

Answer 2

在您的创建方法中，使用save而不是save!

save!会以您看到的方式抛出验证错误，save会向@book对象添加错误消息，以便用户可以在表单中修复它们。

有关详细信息，请参阅the documentation。

def create
  @book = Book.new(book_params)
  if @book.save
    redirect_to :action => 'list'
  else
    @subjects = Subject.all
    render :action => 'new'
  end
end

Ruby Rails：表单应用程序 - 验证失败

2 个答案: