transformResponse method

@override Future transformResponse(RequestOptions options, ResponseBody response)

As an agreement, we return the response when the Options.responseType is ResponseType.stream.

Implementation

@override
Future transformResponse(
    RequestOptions options, ResponseBody response) async {
  if (options.responseType == ResponseType.stream) {
    return response;
  }
  var length = 0;
  var received = 0;
  var showDownloadProgress = options.onReceiveProgress != null;
  if (showDownloadProgress) {
    length = int.parse(
        response.headers[Headers.contentLengthHeader]?.first ?? '-1');
  }
  var completer = Completer();
  var stream =
      response.stream.transform<Uint8List>(StreamTransformer.fromHandlers(
    handleData: (data, sink) {
      sink.add(data);
      if (showDownloadProgress) {
        received += data.length;
        options.onReceiveProgress?.call(received, length);
      }
    },
  ));
  // let's keep references to the data chunks and concatenate them later
  final chunks = <Uint8List>[];
  var finalSize = 0;
  StreamSubscription subscription = stream.listen(
    (chunk) {
      finalSize += chunk.length;
      chunks.add(chunk);
    },
    onError: (Object error, StackTrace stackTrace) {
      completer.completeError(error, stackTrace);
    },
    onDone: () => completer.complete(),
    cancelOnError: true,
  );
  // ignore: unawaited_futures
  options.cancelToken?.whenCancel.then((_) {
    return subscription.cancel();
  });
  // if (options.receiveTimeout > 0) {
  //   try {
  //     await completer.future
  //         .timeout(Duration(milliseconds: options.receiveTimeout));
  //   } on TimeoutException {
  //     await subscription.cancel();
  //     throw DioError(
  //       requestOptions: options,
  //       error: 'Receiving data timeout[${options.receiveTimeout}ms]',
  //       type: DioErrorType.receiveTimeout,
  //     );
  //   }
  // } else {
  await completer.future;
  //}
  // we create a final Uint8List and copy all chunks into it
  final responseBytes = Uint8List(finalSize);
  var chunkOffset = 0;
  for (var chunk in chunks) {
    responseBytes.setAll(chunkOffset, chunk);
    chunkOffset += chunk.length;
  }

  if (options.responseType == ResponseType.bytes) return responseBytes;

  String? responseBody;
  if (options.responseDecoder != null) {
    responseBody = options.responseDecoder!(
      responseBytes,
      options,
      response..stream = Stream.empty(),
    );
  } else {
    responseBody = utf8.decode(responseBytes, allowMalformed: true);
  }
  if (responseBody.isNotEmpty &&
      options.responseType == ResponseType.json &&
      Transformer.isJsonMimeType(
          response.headers[Headers.contentTypeHeader]?.first)) {
    final callback = jsonDecodeCallback;
    if (callback != null) {
      return callback(responseBody);
    } else {
      return json.decode(responseBody);
    }
  }
  return responseBody;
}