RetryInterceptor's exception cannot be catched by future's catchError

[allen218]

Package

dio

Version

5.2.0+1

Output of flutter doctor -v

[√] Flutter (Channel stable, 3.10.2, on Microsoft Windows [Version 10.0.19045.2006], locale zh-CN)
    • Flutter version 3.10.2 on channel stable at F:\Android_Related\Android_ALL\flutter          
    • Upstream repository https://github.com/flutter/flutter.git                                  
    • Framework revision 9cd3d0d9ff (7 weeks ago), 2023-05-23 20:57:28 -0700
    • Engine revision 90fa3ae28f
    • Dart version 3.0.2
    • DevTools version 2.23.1

[√] Windows Version (Installed version of Windows is version 10 or higher)

[√] Android Studio (version 2022.2)
    • Android Studio at F:\Android_Related\Android_ALL\android-studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-b2043.56-9586694)

[√] Android Studio (version 2022.3)
    • Android Studio at F:\Android_Related\android-studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-b2043.56-9884540)

Dart Version

3.0.2

Steps to Reproduce

class RetryInterceptor extends Interceptor {
  final ApiClient apiClient;

  RetryInterceptor({required this.apiClient});

  @override
  void onError(DioException err, ErrorInterceptorHandler handler) async {
    LoginUtils().e("onError", err);

    var retryCount = err.requestOptions.extra["retry_count"] ?? 0;
    err.requestOptions.extra["retry_count"] = retryCount + 1;

    if (isConnectionTimeout(err) && retryCount <= Net.RETRY_MAX_COUNT) {
      // connection timeout retry
      var requestOptions = err.requestOptions;
      Options options = Options(
        method: requestOptions.method,
        sendTimeout: requestOptions.sendTimeout,
        receiveTimeout: requestOptions.receiveTimeout,
        extra: requestOptions.extra,
        headers: requestOptions.headers,
        responseType: requestOptions.responseType,
        contentType: requestOptions.contentType,
        validateStatus: requestOptions.validateStatus,
        receiveDataWhenStatusError: requestOptions.receiveDataWhenStatusError,
        followRedirects: requestOptions.followRedirects,
        maxRedirects: requestOptions.maxRedirects,
        requestEncoder: requestOptions.requestEncoder,
        responseDecoder: requestOptions.responseDecoder,
        listFormat: requestOptions.listFormat,
      );

      sleep(const Duration(seconds: 1));
      var response = await apiClient.dio.request(
        requestOptions.path,
        cancelToken: requestOptions.cancelToken,
        data: requestOptions.data,
        onReceiveProgress: requestOptions.onReceiveProgress,
        options: options,
        onSendProgress: requestOptions.onSendProgress,
        queryParameters: requestOptions.queryParameters,
      );

      return handler.resolve(response);
    }


    super.onError(err, handler);
  }
}

Expected Result

it should throw the exception and future's catchError method can catch this when retry count > RETRY_MAX_COUNT.

Actual Result

It throw an unhandled exception below

E/flutter (20738): [ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: DioException [unknown]: null
E/flutter (20738): Error: SocketException: Failed host lookup: 'xxx.com' (OS Error: No address associated with hostname, errno = 7)
E/flutter (20738): #0      DioMixin.fetch.<anonymous closure> (package:dio/src/dio_mixin.dart:533:7)
E/flutter (20738): #1      _RootZone.runUnary (dart:async/zone.dart:1661:54)
E/flutter (20738): #2      _FutureListener.handleError (dart:async/future_impl.dart:165:22)
E/flutter (20738): #3      Future._propagateToListeners.handleError (dart:async/future_impl.dart:796:47)
E/flutter (20738): #4      Future._propagateToListeners (dart:async/future_impl.dart:817:13)
E/flutter (20738): #5      Future._completeError (dart:async/future_impl.dart:592:5)
E/flutter (20738): #6      _SyncCompleter._completeError (dart:async/future_impl.dart:51:12)
E/flutter (20738): #7      _Completer.completeError (dart:async/future_impl.dart:23:5)
E/flutter (20738): #8      Future.any.onError (dart:async/future.dart:620:45)
E/flutter (20738): #9      _RootZone.runBinary (dart:async/zone.dart:1666:54)
E/flutter (20738): #10     _FutureListener.handleError (dart:async/future_impl.dart:162:22)
E/flutter (20738): #11     Future._propagateToListeners.handleError (dart:async/future_impl.dart:796:47)
E/flutter (20738): #12     Future._propagateToListeners (dart:async/future_impl.dart:817:13)
E/flutter (20738): #13     Future._completeError (dart:async/future_impl.dart:592:5)
E/flutter (20738): #14     Future._asyncCompleteError.<anonymous closure> (dart:async/future_impl.dart:683:7)
E/flutter (20738): #15     _microtaskLoop (dart:async/schedule_microtask.dart:40:21)
E/flutter (20738): #16     _startMicrotaskLoop (dart:async/schedule_microtask.dart:49:5)

not catched by future's catchError method. but it can catch the exception when I comment the RetryInterceptor.

[AlexV525]

• It seems like you're using asynchronized method in onError, please use QueuedInterceptor rather than Interceptor and declare the onError as Future<void> onError(DioException err, ErrorInterceptorHandler handler) async {}.
• Instead of using super.onError(err, handler), it'll be better to use handler.next(err).

[allen218]

• It seems like you're using asynchronized method in onError, please use QueuedInterceptor rather than Interceptor and declare the onError as Future<void> onError(DioException err, ErrorInterceptorHandler handler) async {}.
• Instead of using super.onError(err, handler), it'll be better to use handler.next(err).

Thx! This issue has been resolved. Just call future's then method and handle.resolve() to do that, it works. That last code snippet is blow:

class RetryInterceptor extends Interceptor {
  final ApiClient apiClient;

  RetryInterceptor({required this.apiClient});

  @override
  void onError(DioException err, ErrorInterceptorHandler handler) async {
    LoginUtils().e("onError", err);

    var retryCount = err.requestOptions.extra["retry_count"] ?? 0;
    err.requestOptions.extra["retry_count"] = retryCount + 1;

    if (isConnectionTimeout(err) && retryCount <= Net.RETRY_MAX_COUNT) {
      // connection timeout retry
      var requestOptions = err.requestOptions;
      Options options = Options(
        method: requestOptions.method,
        sendTimeout: requestOptions.sendTimeout,
        receiveTimeout: requestOptions.receiveTimeout,
        extra: requestOptions.extra,
        headers: requestOptions.headers,
        responseType: requestOptions.responseType,
        contentType: requestOptions.contentType,
        validateStatus: requestOptions.validateStatus,
        receiveDataWhenStatusError: requestOptions.receiveDataWhenStatusError,
        followRedirects: requestOptions.followRedirects,
        maxRedirects: requestOptions.maxRedirects,
        requestEncoder: requestOptions.requestEncoder,
        responseDecoder: requestOptions.responseDecoder,
        listFormat: requestOptions.listFormat,
      );
      // err.requestOptions

      sleep(const Duration(seconds: 1));
      return await apiClient.dio
          .request(
            requestOptions.path,
            cancelToken: requestOptions.cancelToken,
            data: requestOptions.data,
            onReceiveProgress: requestOptions.onReceiveProgress,
            options: options,
            onSendProgress: requestOptions.onSendProgress,
            queryParameters: requestOptions.queryParameters,
          )
          .then(handler.resolve,
              onError: (error) => handler
                  .reject(err.copyWith(error: NetworkTimeoutException(err))));
    }

    handler.next(err);
  }
}

Hope that method can help others meet the same issue.