C# Zip Saving byte[] into zip, converting to stream, sending mail as a mail attachment - proper way to attachment document

Question

So below is the code i'm using. Basically it just loops through an array, adds the files to the zip, then saves the zip to a memory stream and then emails the attachment.

When I look at the item in debug I can see that the zipfile has about 20 megabytes of data. When i receive the attachment it only has about 230 bits of data and there is no content. Any thoughts?

byteCount = byteCount + docs[holder].FileSize;
            if (byteCount > byteLimit)
            {
                //create a new stream and save the stream to the zip file
                System.IO.MemoryStream attachmentstream = new System.IO.MemoryStream();
                zip.Save(attachmentstream);

                //create the attachment and send that attachment to the mail
                Attachment data = new Attachment(attachmentstream, "documentrequest.zip");
                theMailMessage.Attachments.Add(data);

                //send Mail
                SmtpClient theClient = new SmtpClient("mymail");
                theClient.UseDefaultCredentials = false;
                System.Net.NetworkCredential theCredential = new System.Net.NetworkCredential("bytebte", "2323232");
                theClient.Credentials = theCredential;
                theClient.Send(theMailMessage);
                zip = new ZipFile();

                //iterate Document Holder
                holder++;
            }
            else
            {
                //create the stream and add it to the zip file
                //System.IO.MemoryStream stream = new System.IO.MemoryStream(docs[holder].FileData);
                zip.AddEntry("DocId_"+docs[holder].DocumentId+"_"+docs[holder].FileName, docs[holder].FileData);
                holder++;

            }

The issue is here Attachment data = new Attachment(attachmentstream, "documentrequest.zip"); once I look at the attachment it has a size of -1 So whats the proper way to attach this item?

Answer 1

I suspect that the call to zip.Save closes the stream after it's written. You'll probably end up having to copy the bytes to an array and then create a new MemoryStream for reading. For example:

//create a new stream and save the stream to the zip file
byte[] streamBytes;
using (var ms = new MemoryStream())
{
    zip.Save(ms);
    // copy the bytes
    streamBytes = ms.ToArray();
}

// create a stream for the attachment
using (var attachmentStream = new MemoryStream(streamBytes))
{
    //create the attachment and send that attachment to the mail
    Attachment data = new Attachment(attachmentstream, "documentrequest.zip");
    theMailMessage.Attachments.Add(data);

    // rest of your code here
}