现有S3文件的Rails ActiveStorage附件

Question

我正在构建一个PDF解析器，它可以触发Sidekiq worker从存储在S3中的文档中OCR解析数据。解析后，数据存储在文档模型中。

如何在不复制文件的情况下将现有的S3存储桶文件附加到ActiveStorage中的Document.attachment.attach中(通过File.open等)在S3？

Answer 1

这可以通过在创建blob之后对其进行轻微的操作来完成。

storage.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'] %>

app/models/document.rb

class Document < ApplicationRecord
  has_one_attached :pdf
end

rails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Document对象的pdf属性。

Answer 2

特洛伊的回答对我很有效！我还发现从对象的s3实例中提取关于该对象的元数据很有帮助。类似于：

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，所以我留下了这个答案，而不是评论:/