HttpPostedFileBase Stream Upload to AWS SDK Bucket has no Data

Question

I'm testing how to upload to AWS using SDK with a sample .txt file from a web app. The file uploads to the Bucket, but the downloaded file from the bucket is just an empty Notepad document without the text from the original uploaded file. I'm new to working with streams, so I'm not sure what could be wrong here. Does anyone see why the data wouldn't be sent in the transfer request? Thanks in advance!

using (var client = new AmazonS3Client(Amazon.RegionEndpoint.USWest1))
{
    //Save File to Bucket
    using (FileStream txtFileStream = (FileStream)UploadedHttpFileBase.InputStream)
    {
        try
        {
            TransferUtility fileTransferUtility = new TransferUtility();
            fileTransferUtility.Upload(txtFileStream, bucketLocation, 
                UploadedHttpFileBase.FileName);
        }
        catch (Exception e)
        {
            e.Message.ToString();
        }
    }
}

EDIT:

Both TransferUtility and PutObjectRequest/PutObjectResponse/AmazonS3Client.PutObject saved a blank text file. Then, after having some trouble instantiating a new FileStream, a MemoryStream used after resetting the starting position to zero still saved a blank text file. Any ideas?

New Code:

using (var client = new AmazonS3Client(Amazon.RegionEndpoint.USWest1))
{
    Stream saveableStream = new MemoryStream();
    using (Stream source = (Stream)UploadedHttpFileBase.InputStream)
    {
        source.Position = 0;
        source.CopyTo(saveableStream);
    }

    //Save File to Bucket                                        
    try
    {
        PutObjectRequest request = new PutObjectRequest
        {
            BucketName = bucketLocation,
            Key = UploadedHttpFileBase.FileName, 
            InputStream = saveableStream
        };
        PutObjectResponse response = client.PutObject(request);
    }
    catch (Exception e)
    {
        e.Message.ToString();
    }
}

Andrey Zakharov Andrey Zakharov · Accepted Answer · 2016-04-19T04:52:24

Most probably that TransferUtility doesn't work good with temporary upload files. Try to copy your input stream somewhere (e.g. into other not-so-temporary file, or even MemoryStream if you're sure it would not give you OutOfMemory at some point). Another thing is to get rid of TransferUtility and use low-level AmazonS3Client.PutObject with which you get finer control over Stream lifetime (do not forget that you'll need to implement some retrying as S3 API is prone to returning random temporary errors).

HttpPostedFileBase Stream Upload to AWS SDK Bucket has no Data

2 Answers