Bug with the clone() method while retrying FormData requests

[anilslabs]

Package

dio

Version

5.3.0

Output of flutter doctor -v

Sookshums-MacBook-Pro:Digital-Health-Passport sookshumlabs$ flutter doctor -v
[✓] Flutter (Channel stable, 3.10.5, on macOS 12.6 21G115 darwin-x64, locale en-IN)
    • Flutter version 3.10.5 on channel stable at /Users/sookshumlabs/development/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 796c8ef792 (6 weeks ago), 2023-06-13 15:51:02 -0700
    • Engine revision 45f6e00911
    • Dart version 3.0.5
    • DevTools version 2.23.1

[✓] Android toolchain - develop for Android devices (Android SDK version 33.0.1)
    • Android SDK at /Users/sookshumlabs/Library/Android/sdk
    • Platform android-33, build-tools 33.0.1
    • ANDROID_HOME = /Users/sookshumlabs/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 11.0.8+10-b944.6916264)
    • All Android licenses accepted.

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    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 14A309
    • CocoaPods version 1.11.2

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[✓] Android Studio (version 4.2)
    • Android Studio at /Applications/Android Studio.app/Contents
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    • Java version OpenJDK Runtime Environment (build 11.0.8+10-b944.6916264)

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[✓] Connected device (4 available)
    • CPH2467 (mobile)   • ab2ba7e2                             • android-arm64  • Android 13 (API 33)
    • iPhone 14 (mobile) • 1B407168-676E-4547-AE54-14AA0C4D55D3 • ios            • com.apple.CoreSimulator.SimRuntime.iOS-16-0 (simulator)
    • macOS (desktop)    • macos                                • darwin-x64     • macOS 12.6 21G115 darwin-x64
    • Chrome (web)       • chrome                               • web-javascript • Google Chrome 114.0.5735.198

[✓] Network resources
    • All expected network resources are available.

• No issues found!

Dart Version

3.0.5

Steps to Reproduce

1. Create a POST request to upload a File with an expired token.
2. Refresh the token using a custom interceptor and retry the failing API request.

onError: (error, handler) async {
  String _refreshTokenPath = instanceUrl() + refreshToken();

  if (error.requestOptions.path != _refreshTokenPath || error.response?.statusCode != 401) {
    return handler.next(error);
  }

  var token = await updateRefreshToken();
  if (token.isEmpty) {
    return handler.next(error);
  }

  if ([nullLocalTokenString, nullServerTokenString, nullServerSessionTokenString].contains(token)) {
    // 401 status;
    // Local token missing
    // New session token not generated
    // Log user out and push login screen
    var _navigationService = serviceLocator<NavigationService>();
    if (_navigationService.navigationKey.currentContext != null) {
      var context = _navigationService.navigationKey.currentContext;
      refreshTokenLoginUserAlertDialog(context!);
    }
  } else {
    error.requestOptions.headers['Authorization'] = 'Bearer $token';
    final opts = Options(
      method: error.requestOptions.method,
      headers: error.requestOptions.headers,
    );

    try {
      if (error.requestOptions.data is FormData && file != null) {
        FormData formData = FormData.fromMap(Map.from(error.requestOptions.data));
        formData.files.add(MapEntry('file', file.clone()));
        error.requestOptions.data = formData;
      }

      final retryFailingRequest = await dio.request<dynamic>(
        error.requestOptions.path,
        options: opts,
        data: error.requestOptions.data,
      );
      return handler.resolve(retryFailingRequest);
    } catch (_error) {
      logger.i(_error);
      return handler.next(error);
    }
  }
}

Expected Result

The file should be uploaded to the server with an updated user session token.

Actual Result

Getting the following exception:

DioException [unknown]: null
Error: FileSystemException: File closed, path = '/Users/sookshumlabs/Library/Developer/CoreSimulator/Devices/1B407168-676E-4547-AE54-14AA0C4D55D3/data/Containers/Data/Application/EBB5CAD9-DF62-4F2E-B57D-98FD2083417C/Documents/test_careplan_file.pdf'

[kuhnroyal]

Related to #1889
@gabrielaraujoz you mind taking a look?

[gabrielaraujoz]

@kuhnroyal @anilslabs I'm taking a look at it but I have a feeling already of what could be going on.

[anilslabs]

@gabrielaraujoz Basically, I'm trying to clone the multipart file in the error handler and retrying the unsuccessful request with an updated session token.

[gabrielaraujoz]

@anilslabs thanks buddy, I could reproduce it. @kuhnroyal I believe the issue lies in us reusing the stream when cloning, specially when using the fromFile() and fromFileSync methods, because in multipartFileFromPath and multipartFileFromPathSync we create a stream from File.openRead() and it is used when making the first request. I tried the following solution and it seems to be working:

1. Store file path and the List<int> bytes value in the class. Note: I could not find a way to do that other than adding two more optional fields to the base constructor, maybe you could help me with that? The code looks like this:

MultipartFile(
    Stream<List<int>> stream,
    this.length, {
    this.filename,
    MediaType? contentType,
    Map<String, List<String>>? headers,
    String? filePath,
    List<int>? value,
  })  : _stream = stream,
        headers = caseInsensitiveKeyMap(headers),
        contentType = contentType ?? MediaType('application', 'octet-stream'),
        _filePath = filePath,
        _valueBytes = value;

2. In the clone method, create a new instance using the same ways we initially create the MultipartFile, like this:

MultipartFile clone() {
    if (_filePath != null) {
      return multipartFileFromPathSync(
        _filePath!,
        filename: filename,
        contentType: contentType,
        headers: headers,
      );
    } else if (_valueBytes != null) {
      return MultipartFile.fromBytes(
        _valueBytes!,
        filename: filename,
        contentType: contentType,
        headers: headers,
      );
    } else {
      throw ArgumentError(
          'Operation is not possible, file path or value is not available');
    }
  }

WDYT? I'll open a PR with this code for you to check.

[kuhnroyal]

What if we deprecate the stream parameter and add a new Stream<List<int>> Function() data provider parameter. This way we can just build a new stream?

[gabrielaraujoz]

@kuhnroyal I'm not sure it resolve this issue when it comes to the File.openRead since it already returns a stream, but we can certainly try.

[kuhnroyal]

Well if it is a Stream provider function, then you get a new Stream every time you call it.

[gabrielaraujoz]

I'll look into it @kuhnroyal - in the meanwhile, I've tested the proposed solution from the PR in my production app in stg and it worked as intended!

[gabrielaraujoz]

@kuhnroyal you're amazing, the solution with the stream provider function worked! I already updated the PR and also:

• Added convenience method for cloning FormData as a whole
• Added regression test with the new method to guarantee we don't get that exception anymore when cloning FormData

[gabrielaraujoz]

@anilslabs hey, this PR should fix your issue in case you're in an emergency: #1903

[anilslabs]

@gabrielaraujoz Thanks. I have tested with the PR and the issue is fixed. Awaiting a pub.dev release.

[gabrielaraujoz]

@AlexV525 hey Alex, sorry to bother you, but do we have any forecast on when we'll be able to have the fix released?

[AlexV525]

Generally I'll do a week cycle for publishing. You can use overrides to use the patch if it's urgent.