Rails ActiveStorage附加到现有S3文件

Question

我正在构建一个PDF解析器，该解析器将激发Sidekiq工作者以OCR解析S3中存储的文档中的数据。解析后，数据存储在Document模型中。

如何将现有的S3存储桶文件追加到Document.attachment.attachActiveStorage中，而不在S3中复制文件（通过File.open等）？

Answer 1

这可以通过在创建 blob 后对 blob 进行轻微操作来完成。

存储.yml

amazon:
  service: S3
  access_key_id: <%= ENV['AWS_ACCESS_KEY_ID'] %>
  secret_access_key: <%= ENV['AWS_SECRET_ACCESS_KEY'] %>
  region: <%= ENV['AWS_REGION'] %>
  bucket: <%= ENV['S3_BUCKET'] %>

应用程序/模型/document.rb

class Document < ApplicationRecord
  has_one_attached :pdf
end

导轨控制台

key = "<S3 Key of the existing file in the same bucket that storage.yml uses>"

# Create an active storage blob that will represent the file on S3
params = { 
  filename: "myfile.jpg", 
  content_type:"image/jpeg", 
  byte_size:1234, 
  checksum:"<Base 64 encoding of the MD5 hash of the file's contents>" 
}
blob = ActiveStorage::Blob.create_before_direct_upload!(params)

# By default, the blob's key (S3 key, in this case) a secure (random) token
# However, since the file is already on S3, we need to change the 
# key to match our file on S3
blob.update_attributes key:key

# Now we can create a document object connected to your S3 file
d = Document.create! pdf:blob.signed_id

# in your view, you can now use
url_for d.pdf

此时，您可以像使用任何其他活动存储附件一样使用对象的pdf属性Document。

Answer 2

特洛伊的答案对我很有用！我还发现从对象的s3实例中提取有关该对象的元数据很有帮助。就像是：

s3 = Aws::S3::Resource.new(region: "us-west-1")
obj = s3.bucket("my-bucket").object("myfile.jpg")    

params = {
    filename: obj.key, 
    content_type: obj.content_type, 
    byte_size: obj.size, 
    checksum: obj.etag.gsub('"',"")
}

我只有46分，所以我把它留为答案而不是评论：/