Rails:使用回形针防止重复上传照片? [英] Rails: Preventing Duplicate Photo Uploads with Paperclip?

问题描述

如果用户尝试使用 Paperclip 将同一张照片两次上传到 Rails 应用程序，是否会引发验证错误?Paperclip 似乎不提供此功能...

Is there anyway to throw a validation error if a user tries to upload the same photo twice to a Rails app using Paperclip? Paperclip doesn't seem to offer this functionality...

我正在使用 Rails 2.3.5 和 Paperclip(显然).

I'm using Rails 2.3.5 and Paperclip (obviously).

解决方案:(或至少其中之一)

SOLUTION: (or one of them, at least)

根据 Beerlington 的建议，我决定进行 MD5 校验和比较:

Using Beerlington's suggestion, I decided to go with an MD5 Checksum comparison:

class Photo < ActiveRecord::Base
  #...
  has_attached_file :image #, ...

  before_validation_on_create :generate_md5_checksum
  validate :unique_photo
  #...

  def generate_md5_checksum
    self.md5_checksum = Digest::MD5.hexdigest(image.to_file.read)
  end

  def unique_photo
    photo_digest = self.md5_checksum
    errors.add_to_base "You have already uploaded that file!" unless User.find(self.user_id).photos.find_by_md5_checksum(photo_digest).nil?
  end

  # ...
end

然后我在我的 photos 表中添加了一个名为 md5_checksum 的列，瞧！现在，如果您尝试上传同一张照片，我的应用会抛出验证错误！

Then I just added a column to my photos table called md5_checksum, and voila! Now my app throws a validation error if you try to upload the same photo!

不知道这是多么有效/低效，所以欢迎重构！

No idea how efficient/inefficient this is, so refactoring's welcome!

谢谢！

推荐答案

对图像文件做 MD5 怎么样?如果是完全相同的文件，则两个图像的 MD5 哈希值将相同.

What about doing an MD5 on the image file? If it is the exact same file, the MD5 hash will be the same for both images.

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