fetch method

  1. @override
Future<ResponseBody> fetch(
  1. RequestOptions options,
  2. Stream<List<int>>? requestStream,
  3. Future? cancelFuture
)
override

We should implement this method to make real http requests.

options: The request options

requestStream The request stream, It will not be null only when http method is one of "POST","PUT","PATCH" and the request body is not empty.

We should give priority to using requestStream(not options.data) as request data. because supporting stream ensures the onSendProgress works.

cancelFuture: When cancelled the request, cancelFuture will be resolved! you can listen cancel event by it, for example:

 cancelFuture?.then((_)=>print("request cancelled!"))

cancelFuture: will be null when the request is not set CancelToken.

Implementation

@override
Future<ResponseBody> fetch(
  RequestOptions options,
  Stream<List<int>>? requestStream,
  Future? cancelFuture,
) async {
  if (_closed) {
    throw Exception(
        "Can't establish connection after [HttpClientAdapter] closed!");
  }
  var _httpClient = _configHttpClient(cancelFuture, options.connectTimeout);
  Future requestFuture = _httpClient.openUrl(options.method, options.uri);

  void _throwConnectingTimeout() {
    throw DioError(
      request: options,
      error: 'Connecting timed out [${options.connectTimeout}ms]',
      type: DioErrorType.CONNECT_TIMEOUT,
    );
  }

  late HttpClientRequest request;
  try {
    if (options.connectTimeout > 0) {
      request = await requestFuture
          .timeout(Duration(milliseconds: options.connectTimeout));
    } else {
      request = await requestFuture;
    }

    //Set Headers
    options.headers.forEach((k, v) => request.headers.set(k, v));
  } on SocketException catch (e) {
    if (e.message.contains('timed out')) _throwConnectingTimeout();
    rethrow;
  } on TimeoutException {
    _throwConnectingTimeout();
  }

  if (options.method != 'GET' && requestStream != null) {
    // Transform the request data
    await request.addStream(requestStream);
  }
  Future future = request.close();
  if (options.connectTimeout > 0) {
    future = future.timeout(Duration(milliseconds: options.connectTimeout));
  }
  late HttpClientResponse responseStream;
  try {
    responseStream = await future;
  } on TimeoutException {
    _throwConnectingTimeout();
  }

  // https://github.com/dart-lang/co19/issues/383
  var stream =
      responseStream.transform<Uint8List>(StreamTransformer.fromHandlers(
    handleData: (data, sink) {
      sink.add(Uint8List.fromList(data));
    },
  ));

  var headers = <String, List<String>>{};
  responseStream.headers.forEach((key, values) {
    headers[key] = values;
  });
  return ResponseBody(
    stream,
    responseStream.statusCode,
    headers: headers,
    isRedirect:
        responseStream.isRedirect || responseStream.redirects.isNotEmpty,
    redirects: responseStream.redirects
        .map((e) => RedirectRecord(e.statusCode, e.method, e.location))
        .toList(),
    statusMessage: responseStream.reasonPhrase,
  );
}