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MimeKit

ImapFolderGetStream(UniqueId, String, CancellationToken, ITransferProgress) Method

Get a substream of the specified body part.

Namespace: MailKit.Net.Imap
Assembly: MailKit (in MailKit.dll) Version: 4.7.1
Syntax
C#
public override Stream GetStream(
	UniqueId uid,
	string section,
	CancellationToken cancellationToken = default,
	ITransferProgress progress = null
)

Parameters

uid  UniqueId
The UID of the message.
section  String
The desired section of the message.
cancellationToken  CancellationToken  (Optional)
The cancellation token.
progress  ITransferProgress  (Optional)
The progress reporting mechanism.

Return Value

Stream
The stream.

Implements

IMailFolderGetStream(UniqueId, String, CancellationToken, ITransferProgress)
IMailFolderGetStream(UniqueId, String, CancellationToken, ITransferProgress)
Exceptions
ExceptionCondition
ArgumentExceptionuid is invalid.
ArgumentNullExceptionsection is null.
ObjectDisposedException The ImapClient has been disposed.
ServiceNotConnectedException The ImapClient is not connected.
ServiceNotAuthenticatedException The ImapClient is not authenticated.
FolderNotOpenException The ImapFolder is not currently open.
MessageNotFoundException The IMAP server did not return the requested message stream.
OperationCanceledException The operation was canceled via the cancellation token.
IOException An I/O error occurred.
ImapProtocolException The server's response contained unexpected tokens.
ImapCommandException The server replied with a NO or BAD response.
Remarks

Gets a substream of the specified message.

For more information about how to construct the section, see Section 6.4.5 of RFC3501.

Example
C#
public static void SaveAttachments (string baseDirectory)
{
    using (var client = new ImapClient ()) {
        client.Connect ("imap.gmail.com", 993, SecureSocketOptions.SslOnConnect);

        client.Authenticate ("username", "password");

        client.Inbox.Open (FolderAccess.ReadOnly);

        // search for messages where the Subject header contains either "MimeKit" or "MailKit"
        var query = SearchQuery.SubjectContains ("MimeKit").Or (SearchQuery.SubjectContains ("MailKit"));
        var uids = client.Inbox.Search (query);

        // fetch summary information for the search results (we will want the UID and the BODYSTRUCTURE
        // of each message so that we can extract the text body and the attachments)
        var items = client.Inbox.Fetch (uids, MessageSummaryItems.UniqueId | MessageSummaryItems.BodyStructure);

        foreach (var item in items) {
            // determine a directory to save stuff in
            var directory = Path.Combine (baseDirectory, item.UniqueId.ToString ());

            // create the directory
            Directory.CreateDirectory (directory);

            // now iterate over all of the attachments and decode/save the content to disk
            foreach (var attachment in item.Attachments) {
                // default to using the sending client's suggested fileName value
                string fileName = attachment.FileName;

                if (string.IsNullOrEmpty (fileName)) {
                    // the FileName wasn't defined, so generate one...
                    if (!MimeTypes.TryGetExtension (attachment.ContentType.MimeType, out string extension))
                        extension = ".dat";

                    fileName = Guid.NewGuid ().ToString () + extension;
                }

                // we'll need the Content-Transfer-Encoding value so that we can decode it...
                ContentEncoding encoding;

                if (string.IsNullOrEmpty (attachment.ContentTransferEncoding) || !MimeUtils.TryParse (attachment.ContentTransferEncoding, out encoding))
                    encoding = ContentEncoding.Default;

                // if all we want is the content (rather than the entire MIME part including the headers), then
                // we want the ".TEXT" section of the part
                using (var stream = client.Inbox.GetStream (item.UniqueId, attachment.PartSpecifier + ".TEXT")) {
                    // wrap the attachment content in a MimeContent object to help us decode it
                    using (var content = new MimeContent (stream, encoding)) {
                        var path = Path.Combine (directory, fileName);

                        // decode the attachment content to the file stream
                        using (var output = File.Create (path))
                            content.DecodeTo (output);
                    }
                }
            }
        }

        client.Disconnect (true);
    }
}
See Also