JsonCacheInfoRepository: FormatException: Unexpected end of input (at character 1) ^

[gemunet]

🐛 Bug Report

occasionally this error is generated when initializing CacheManager with JsonCacheInfoRepository

Fatal Exception: io.flutter.plugins.firebase.crashlytics.FlutterError: FormatException: Unexpected end of input (at character 1)

^

       at .jsonDecode(dart:convert)
       at JsonCacheInfoRepository._readFile(json_cache_info_repository.dart:143)
       at JsonCacheInfoRepository.open(json_cache_info_repository.dart:40)
       at new CacheStore.<fn>(cache_store.dart:34)

This happens when the {databaseName}.json file is created but empty and jsonString = ""

JsonCacheInfoRepository.dart: _readFile()
final json = jsonDecode(jsonString) as List<dynamic>;

A possible solution would be to check that the file is not empty before decoding the json

    if (await file.exists() && await file.length() > 0) {
      try {
        final jsonString = await file.readAsString();
        final json = jsonDecode(jsonString) as List<dynamic>;

note: I don't know why the json file is empty and not with an empty list []

Expected behavior

no error

Configuration

Doctor summary (to see all details, run flutter doctor -v): [√] Flutter (Channel stable, 3.16.1, on Microsoft Windows [Versi¢n 10.0.22631.3296], locale es-CL) [√] Windows Version (Installed version of Windows is version 10 or higher) [√] Android toolchain - develop for Android devices (Android SDK version 34.0.0) [√] Chrome - develop for the web [√] Visual Studio - develop Windows apps (Visual Studio Build Tools 2022 17.8.2) [√] Android Studio (version 2022.3) [√] VS Code (version 1.87.2) [√] Connected device (4 available) [√] Network resources

• No issues found!

Version: 3.3.1

Platform:

• [ ] :iphone: iOS
• [x] :robot: Android 13 (AP I33)

[Migo-17]

Any updates on when this issue will be fixed ?

[aazgersky]

Faced with same problem on iOS devices

[duocnguyen6799]

Is there any update on this? I'm facing the same issue!

[bothyculture]

I get this issue a lot too

[manoj-simform]

Do we have any update on this?

[aazgersky]

@bothyculture Why you decided to close your PR? We really need this fix

[hayatshin]

Same here. any update on this?

[HeftyCoder]

I don't think this is caused when creating the file. Or at least, I haven't gotten the error when creating the .json file. (Note that I am using the JsonCacheInfoRepository.withFile constructor, but I don't think there is a difference).

I have had this happen when I abruptly closed the app from my IDE and then re-opened it, which somehow caused an existing database file to be emptied completely. I had multiple CacheManagers, but only one at a time active. These were closed and opened when users were logging to different servers.

I then noticed that despite there being multiple CacheManagers, I had them all with the same cacheKey. Even though only one was active at a time, it seems that this wasn't enough, and probably a race condition was happening where one CacheManager instance corrupted one of the .json files. I made them all have different keys and I have not seen the issue since.

If you have seen this issue with only one CacheManager, then there is indeed something more serious going on, and I would suggest at least not closing the app abruptly through the IDE. Or you might have forgotten to dispose your CacheManager?