Question

See also this question: Can I pass a System.Net.MailMessage to a WCF service?

I’d like to add attachments to the mail being sent. Attachments are either files on the local disc, or dynamically created Streams. A WCF contract can contain a Stream, but only when all arguments are of type Stream. So, what is the best way to pass one or more Attachments to a WCF service?

Answer 1

Alright I’ve solved this myself. The trick here is to convert the attachment to a Base64 encodes string, much the same way email systems do this. I’ve created a class to handle this. Posted here for others:

 [DataContract]     public class EncodedAttachment     {         [DataMember(IsRequired=true)]         public string Base64Attachment;          [DataMember(IsRequired = true)]         public string Name;          /// <summary>         /// One of the System.Net.Mime.MediaTypeNames         /// </summary>         [DataMember(IsRequired = true)]         public string MediaType;     }   public EncodedAttachment CreateAttachment(string fileName)         {             EncodedAttachment att = new EncodedAttachment();             if (!File.Exists(fileName))                 throw new FileNotFoundException('Cannot create attachment because the file was not found', fileName);              FileInfo fi = new FileInfo(fileName);             att.Name = fi.Name;             att.MediaType = System.Net.Mime.MediaTypeNames.Text.Plain;              using (FileStream reader = new FileStream(fileName, FileMode.Open))             {                 byte[] buffer = new byte[reader.Length];                 reader.Read(buffer, 0, (int)reader.Length);                 att.Base64Attachment = Convert.ToBase64String(buffer);             }             return att;         } 

And on the client side:

public void SendEmail(SmallMessage msg)         {             using (MailMessage message = new MailMessage())             {                 message.Body = msg.Body;                 message.Subject = msg.Subject;                 message.To.Add(new MailAddress(msg.To));                 message.From = new MailAddress(msg.From);                 foreach (EncodedAttachment att in msg.Attachments)                 {                     message.Attachments.Add(CreateAttachment(att));                 }                  SmtpClient client = new SmtpClient();                 client.Send(message);             }         }   Attachment CreateAttachment(EncodedAttachment encodedAtt) {     MemoryStream reader = new MemoryStream(Convert.FromBase64String(encodedAtt.Base64Attachment));     Attachment att = new Attachment(reader, encodedAtt.Name, encodedAtt.MediaType);     return att;             }