用一个例子更容易：

class User < ActiveRecord::Base
  has_attached_file :attachment

  validates_attachment_content_type :attachment, content_type: /\Aimage\/.*\z/
end

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附加文件：

>> User.create!(attachment: File.open("avatar.png"))
  TRANSACTION (0.1ms)  begin transaction
  User Create (0.3ms)  INSERT INTO "users" ("attachment_file_name", "attachment_content_type", "attachment_file_size", "attachment_updated_at") VALUES (?, ?, ?, ?)  [["attachment_file_name", "avatar.png"], ["attachment_content_type", "image/png"], ["attachment_file_size", 8229], ["attachment_updated_at", "2023-12-01 05:14:12.369915"]]
  TRANSACTION (5.4ms)  commit transaction
=> #<User id: 1, attachment_file_name: "avatar.png", attachment_content_type: "image/png", attachment_file_size: 8229, attachment_updated_at: "2023-12-01 05:14:12.369915603 +0000">

型
这是存储文件的默认路径：

>> Paperclip::Attachment.default_options[:url]
=> "/system/:class/:attachment/:id_partition/:style/:filename"

x

$ ls public/system/**/*.png
public/system/users/attachments/000/000/001/original/avatar.png

public/
system/
users/       - :class        # `User.name.underscore.pluralize`
                             # https://github.com/thoughtbot/paperclip/blob/main/lib/paperclip/interpolations.rb#L88

attachments/ - :attachment   # pluralized attachment name
                             #                     vvvvvvvvvv
                             # `has_attached_file :attachment`
                             # https://github.com/thoughtbot/paperclip/blob/main/lib/paperclip/interpolations.rb#L191

000/000/001/ - :id_partition # id padded with zeros and split in 3 groups (9 digits total)
                             # https://github.com/thoughtbot/paperclip/blob/main/lib/paperclip/interpolations.rb#L174

original/    - :style        # "original" is default, this is what you've uploaded
                             # https://github.com/thoughtbot/paperclip/blob/main/lib/paperclip/interpolations.rb#L197

avatar.png   - :filename

的一种或多种
如果您只能从数据库端工作

sqlite> select * from users;
+----+----------------------+-------------------------+----------------------+----------------------------+
| id | attachment_file_name | attachment_content_type | attachment_file_size |   attachment_updated_at    |
+----+----------------------+-------------------------+----------------------+----------------------------+
| 1  | avatar.png           | image/png               | 8229                 | 2023-12-01 05:14:12.369915 |
+----+----------------------+-------------------------+----------------------+----------------------------+

public/
system/
users/       - :class        # most likely the same as table name

attachments/ - :attachment   # attachment_file_name
                             # ^^^^^^^^^^s

000/000/001/ - :id_partition # padded id - you'll need to work that one out

original/    - :style        # "original" - this is not in the db

avatar.png   - :filename     # attachment_file_name

的字符串