streamText function

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

Streams plain text to the client chunk by chunk.

Sets Content-Type: text/plain and Transfer-Encoding: chunked automatically. The callback receives a DartoTextStreamWriter.

app.get('/words', (c) => streamText(c, (s) async {
  for (final word in ['Hello', ' ', 'World']) {
    await s.write(word);
    await s.sleep(Duration(milliseconds: 300));
  }
}));

Implementation

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

  final writer = DartoTextStreamWriter._(httpRes);

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

  return const Response.sent();
}