Rails回形针图像URL上传 - 不保存图像

Question

对于 Rails 来说还是很新的。我有一个书评应用程序，通过回形针上传图片。如果您通过文件字段上传图像，它工作正常，但我想添加通过链接上传图像的功能。到目前为止，我一直很失败，所以我转向你们。导轨和回形针都是最新版本。

当我提交表单时，控制台中会显示以下内容：

Started POST "/books" for ::1 at 2015-12-24 20:49:55 -0600
Processing by BooksController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"UGX2ed+eVP9nuLoUEo/pDNX6CpICbOZgIv6U3OPcxmbRtmmIesRNki1Zv/7rQcOlqQEpsAuZVx9NjCe9mdizcQ==", "category_id"=>"", "book_url"=>"http://ecx.images-amazon.com/images/I/41aQPTCmeVL.jpg", "book"=>{"title"=>"The Hobbit", "description"=>"A wonderful journey", "author"=>"J.R.R Tolkien"}, "commit"=>"Create Book"}
  User Load (0.9ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ?  ORDER BY "users"."id" ASC LIMIT 1  [["id", 1]]
   (0.4ms)  begin transaction
  SQL (0.9ms)  INSERT INTO "books" ("title", "description", "author", "user_id", "created_at", "updated_at") VALUES (?, ?, ?, ?, ?, ?)  [["title", "The Hobbit"], ["description", "A wonderful journey"], ["author", "J.R.R Tolkien"], ["user_id", 1], ["created_at", "2015-12-25 02:49:55.555658"], ["updated_at", "2015-12-25 02:49:55.555658"]]
   (1.4ms)  commit transaction
Redirected to http://localhost:3000/
Completed 302 Found in 50ms (ActiveRecord: 3.6ms)

它似乎正在确认图像 url，但没有保存它。 它显示为 missing.png。

如果我在控制台中检查 Book.last，它会显示 image_url 为 nil：

SELECT  "books".* FROM "books"  ORDER BY "books"."id" DESC LIMIT 1
 => #<Book id: 25, title: "The Hobbit", description: "kJSdfkjsdkfjsjf", author: "J.R.R Tolkien", created_at: "2015-12-25 02:37:10", updated_at: "2015-12-25 02:37:10", user_id: 1, category_id: 1, book_img_file_name: nil, book_img_content_type: nil, book_img_file_size: nil, book_img_updated_at: nil, image_remote_url: nil, image_url_file_name: nil, image_url_content_type: nil, image_url_file_size: nil, image_url_updated_at: nil> 

很明显我的设置有误。我已经关注了我能找到的所有链接，并尝试将它们与我最初的工作方式结合起来。

这是我的 Book 模型：

class Book < ActiveRecord::Base
  belongs_to :user
  belongs_to :category
  has_many :reviews
  attr_reader :image_url

  has_attached_file :book_img, :styles => { :book_index => "250x350>", :book_show => "325x475>" }
  has_attached_file :image_url, :styles => { :book_index => "250x350>", :book_show => "325x475>" }, :url => "/:class/:attachment/:id/:style_:basename.:extension"
  validates_attachment_content_type :book_img, :content_type => /\Aimage\/.*\Z/

  def image_url=(url_value)
    self.image = URI.parse(url_value)

    @image_url = url_value
  end
end

这是来自书籍控制器的书籍参数：

def book_params
      params.require(:book).permit(:title, :description, :author, :category_id, :book_img, :image_url)
end

这里是从 book_img 实际有效的迁移，然后是对 image_url 无效的迁移。

class AddAttachmentBookImgToBooks < ActiveRecord::Migration
  def self.up
    change_table :books do |t|
      t.attachment :book_img
    end
  end

  def self.down
    remove_attachment :books, :book_img
  end
end

class AddAttachmentImageUrlToBooks < ActiveRecord::Migration
  def self.up
    change_table :books do |t|
      t.attachment :image_url
    end
  end

  def self.down
    remove_attachment :books, :image_url
  end
end

这是部分表单

<%= simple_form_for @book, :html => { :multipart => true } do |f| %>
  <% if @book.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@book.errors.count, "error") %> prohibited this user from being saved:</h2>

      <ul>
        <% @book.errors.full_messages.each do |msg| %>
          <li><%= msg %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

  <%= select_tag(:category_id, options_for_select(@categories), :prompt => "Select a Category") %>
  <%= f.file_field :book_img %>
  <%= text_field_tag 'image_url' %>
  <%= f.input :title, label: "Book Title" %>
  <%= f.input :description %>
  <%= f.input :author %>
  <%= f.button :submit, :class => 'btn-custom2' %>
<% end %>

以及Schema.rb文件的相关部分

create_table "books", force: :cascade do |t|
    t.string   "title"
    t.text     "description"
    t.string   "author"
    t.datetime "created_at",             null: false
    t.datetime "updated_at",             null: false
    t.integer  "user_id"
    t.integer  "category_id"
    t.string   "book_img_file_name"
    t.string   "book_img_content_type"
    t.integer  "book_img_file_size"
    t.datetime "book_img_updated_at"
    t.string   "image_remote_url"
    t.string   "image_url_file_name"
    t.string   "image_url_content_type"
    t.integer  "image_url_file_size"
    t.datetime "image_url_updated_at"
end

我确定我可能遗漏了一些如此简单的东西。当我打开似乎与此问题相关的每个链接并且不知道还能尝试什么时，它只会变得更加混乱。任何帮助将不胜感激！

如果有任何我忘记包含的细节，请告诉我。谢谢

Answer 1

替换
<%= text_field_tag 'image_url' %>
与
<%= f.input 'image_url' %>

Answer 2

将表单中的 book_url 更改为 book_img 或 image_url (-: