Play 2.x : Reactive file upload with Iteratees

Question

I will start with the question: How to use Scala API\'s Iteratee to upload a file to the cloud storage (Azure Blob Storage in my case, but I don\'t thi

Answer 1

For those who are also trying to figure out a solution of this streaming problem, instead of writing a whole new BodyParser, you can also use what has already been implemented in parse.multipartFormData. You can implement something like below to overwrite the default handler handleFilePartAsTemporaryFile.

def handleFilePartAsS3FileUpload: PartHandler[FilePart[String]] = {
  handleFilePart {
    case FileInfo(partName, filename, contentType) =>

      (rechunkAdapter &>> writeToS3).map {
        _ =>
          val compRequest = new CompleteMultipartUploadRequest(...)
          amazonS3Client.completeMultipartUpload(compRequest)
          ...
      }
  }
}

def multipartFormDataS3: BodyParser[MultipartFormData[String]] = multipartFormData(handleFilePartAsS3FileUpload)

I am able to make this work but I am still not sure whether the whole upload process is streamed. I tried some large files, it seems the S3 upload only starts when the whole file has been sent from the client side.

I looked at the above parser implementation and I think everything is connected using Iteratee so the file should be streamed. If someone has some insight on this, that will be very helpful.