如何使用Viewpoint将EWS电子邮件附件中继到REST端点
How to relay EWS email attachments to a REST endpoint using Viewpoint

我设法通过使用StringIO并给它一个:path来上传文件

# email is a Viewpoint::EWS::Types::Message
# email_endpoint is a RestClient::Resource

attachments = email.attachments.map do |attachment|
  file = StringIO.new(Base64.decode64(attachment.content))
  file.class.class_eval { attr_accessor :original_filename, :content_type, :path }
  file.original_filename = attachment.file_name
  file.content_type = attachment.content_type
  file
end

response = email_endpoint.post(
  email: {
    subject: email.subject,
    attachments: attachments
  }
)

rest-client库将自动处理响应:path和:read作为文件的对象，并使用分段上传。

然后，每个附件在Rails中显示为具有正确文件名的ActionDispatch::Http::UploadedFile 。