stream function

Future<Response> stream(Context c, Future<void> callback(DartoStreamWriter writer), { Future<void> onError(Object error, DartoStreamWriter writer)?, })

Streams raw binary data to the client.

Sets Transfer-Encoding: chunked automatically. The callback receives a DartoStreamWriter to send chunks. Errors in callback are forwarded to onError; without it they are silently swallowed (the response is always closed cleanly).

app.get('/bytes', (c) => stream(c, (s) async {
  await s.write([72, 101, 108, 108, 111]);
}));

Implementation

Future<Response> stream(
  Context c,
  Future<void> Function(DartoStreamWriter writer) callback, {
  Future<void> Function(Object error, DartoStreamWriter writer)? onError,
}) async {
  final httpRes = c.res.raw;
  httpRes.statusCode = 200;
  httpRes.headers.set(HttpHeaders.transferEncodingHeader, 'chunked');

  final writer = DartoStreamWriter._(httpRes);
  unawaited(httpRes.done.then((_) {}, onError: (_) {
    writer._aborted = true;
    writer._onAbortCallback?.call();
  }));

  try {
    await callback(writer);
  } catch (e) {
    if (onError != null) await onError(e, writer);
  } finally {
    try {
      await httpRes.close();
    } catch (_) {}
  }

  return const Response.sent();
}