Why is CloudBlockBlob.DownloadToStream always returning an empty stream?

Question

I have the following code:

public static void UploadStreamToBlob(Stream stream, string containerName, string blobName)
{
    CloudStorageAccount storageAccount = 
        CloudStorageAccount.Parse(CloudConfigurationManager.GetSetting("StorageConnectionString"));
    CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

    CloudBlobContainer blobContainer = blobClient.GetContainerReference(containerName);
    blobContainer.CreateIfNotExists();
    blobContainer.SetPermissions(
        new BlobContainerPermissions
        {
            PublicAccess = BlobContainerPublicAccessType.Blob
        });

    CloudBlockBlob blockBlob = blobContainer.GetBlockBlobReference(blobName);
    long streamlen = stream.Length;  <-- This shows 203 bytes
    blockBlob.UploadFromStream(stream);        
}

and

public static Stream DownloadStreamFromBlob(string containerName, string blobName)
{
    CloudStorageAccount storageAccount = 
        CloudStorageAccount.Parse(CloudConfigurationManager.GetSetting("StorageConnectionString"));
    CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

    CloudBlobContainer blobContainer = blobClient.GetContainerReference(containerName);

    Stream stream = new MemoryStream();
    CloudBlockBlob blockBlob = blobContainer.GetBlockBlobReference(blobName);

    if (blockBlob.Exists())
    {
        blockBlob.DownloadToStream(stream);
        long streamlen = stream.Length;  <-- This shows 0 bytes
        stream.Position = 0;          
    }

    return stream;
}

I'm running this in the Azure emulator, which I have pointed to my Sql Server.

From what I can tell, it appears that the UploadFromStream is sending the data correctly, however, if I try and run the DownloadStreamFromBlob, it returns a 0 length stream. The blockBlob.Exists is returning true, so I assume it's there. I just can't figure out why my stream is empty.

Btw, I'm passing in test and test for containerName and blobName on both calls.

Any ideas?

Answer 1

Ah, I figured it out...

The following lines:

long streamlen = stream.Length;
blockBlob.UploadFromStream(stream);   

need to be changed to

long streamlen = stream.Length;  
stream.Position = 0;
blockBlob.UploadFromStream(stream);