Carrierwave：文件名/ store_dir中的文件哈希和模型ID [英] Carrierwave: file hash and model id in filename/store_dir

问题描述

我在Rails 4项目中使用了载波，用于文件存储进行开发和测试，并在雾存储中（用于存储在Amazon S3上）进行生产。

I'm using carrierwave in a Rails 4 project with the file storage for development and testing and the fog storage (for storing on Amazon S3) for production.

我想使用以下路径保存文件：

I would like to save my files with paths like this:

/model_class_name/part_of_hash/another_part_of_hash/hash-model_id.file_extension

（例如： /images/12/34/1234567-89.png 其中1234567是SHA1文件内容的哈希值，而89是数据库中关联图像模型的ID）。

(example: /images/12/34/1234567-89.png where 1234567 is the SHA1 hash of the file content and 89 is the id of the associated image model in the database).

到目前为止，我尝试过的操作是：

What I tried so far is this:

class MyUploader < CarrierWave::Uploader::Base

  def store_dir
    "#{model.class.name.underscore}/#{sha1_for(file)[0..1]}/#{sha1_for(file)[2..3]}"
  end

  def filename
    "#{sha1_for(file)}-#{model.id}.#{file.extension}" if original_file
  end

  private

    def sha1_for file
      Digest::SHA1.hexdigest file.read
    end

end

这不起作用，因为：

• model.id 在调用文件名时不可用


• 文件在调用 store_dir 时并不总是可用

• model.id is not available when filename is called
• file is not always available when store_dir is called

所以，出现我的问题：

• 是否可以在文件名中使用模型ID /属性？ 此链接说不应该这样做；


• 是否可以在 store_dir 中使用文件内容/属性？我没有找到任何相关文档，但到目前为止我的经历是否（请参见上文）。


• 如何实现文件/目录命名，以使内容与我概述的内容尽可能接近

• is it possible to use model ids/attributes within filename? This link says it should not be done; is there a way to work around it?
• is it possible to use file content/attributes within store_dir? I found no documentation on this but my experiences so far say "no" (see above).
• how would you implement file/directory naming to get something as close as possible to what I outlined in the beginning?

推荐答案

• 包括ID由于文件名存储在数据库中，但ID尚不可用，因此在创建时不能使用文件名中的。 （公认的，极端的）解决方法是在create上使用一个临时值，然后在 after_commit :: create 上移动文件并更改数据库中的名称。可能可以通过 after_create 对此进行优化，但我将由您自己决定。 （这是载波实际上传的位置文件）。

  • Including the id in the filename on create may not be possible, since the filename is stored in the database but the id isn't available yet. An (admittedly rather extreme) workaround would be to use a temporary value on create, and then after_commit on: :create, move the file and change the name in the database. It may be possible to optimize this with an after_create, but I'll leave that up to you. (This is where carrierwave actually uploads the file.)

    在 store_dir 中直接包含文件属性 不可能，因为 store_dir 用于计算 url - url 将需要知道sha1，这需要访问文件，这需要知道url，等等。解决方法非常明显：将感兴趣的属性（在本例中为sha1）缓存在模型的数据库记录，并在 store_dir 中使用。

    Including file attributes directly within the store_dir isn't possible, since store_dir is used to calculate the url—url would require knowing the sha1, which requires having access to the file, which requires knowing the url, etc. The workaround is pretty obvious: cache the attributes in which you're interested (in this case the sha1) in the model's database record, and use that in the store_dir.

    id-in-文件名方法是使用其他值（例如uuid），并将该值存储在数据库中。关于此处。

    The simpler variant on the id-in-filename approach is to use some other value, such as a uuid, and store that value in the database. There are some notes on that here.

    这篇关于Carrierwave：文件名/ store_dir中的文件哈希和模型ID的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！