Fetching blobs from filesystem results in blob-size: 0

[ma-pe]

Environment

React Native Environment Info:
    System:
      OS: macOS High Sierra 10.13.4
      CPU: x64 Intel(R) Core(TM) i7-7820HQ CPU @ 2.90GHz
      Memory: 769.02 MB / 16.00 GB
      Shell: 2.7.1 - /usr/local/bin/fish
    Binaries:
      Node: 8.9.3 - ~/.nvm/versions/node/v8.9.3/bin/node
      Yarn: 1.7.0 - /usr/local/bin/yarn
      npm: 6.1.0 - ~/.nvm/versions/node/v8.9.3/bin/npm
      Watchman: 4.9.1 - /usr/local/bin/watchman
    SDKs:
      iOS SDK:
        Platforms: iOS 11.4, macOS 10.13, tvOS 11.4, watchOS 4.3
    IDEs:
      Android Studio: 3.0 AI-171.4443003
      Xcode: 9.4/9F1027a - /usr/bin/xcodebuild
    npmPackages:
      react: 16.4.1 => 16.4.1
      react-native: 0.56.0-rc => 0.56.0-rc

Description

After upgrading from react native 0.55.4 (which introduced blob fetching) to react native 0.56.0-rc I experience issues with blob fetching on iOS (android not tested). When fetching an image/video from filesystem and building a blob from it, the blob-size is 0.

const mediaResponse = await fetch('file:///var/mobile/Containers/Data/Application/.../Library/CachesCamera/....mov');

// convert response to blob
const mediaBlob = await mediaResponse.blob();

console.log(mediaBlob.size) 
// 0

I am aware of this react-native-blob-test repo but these tests doesn't seem to fail on size === 0 since an && operator is used instead of an || operator : https://github.com/expo/react-native-blob-test/blob/c0dbd66f4e2a193a5031c52c9b49ea2a6b4419ed/index.common.js#L291

Steps to Reproduce

https://github.com/expo/react-native-blob-test/blob/master/index.common.js#L134

Expected Behavior

Since the image/video exists (i can save it via CameraRoll.saveToCameraRoll) the resulting blob should have a valid size (positive number).

Actual Behavior

The blob has a size of 0.

[ma-pe]

initial blob fetch support was added with the commits be56a3e and 854c233 by @satya164 and @fkgozali.

Possible impacting commits in the last release were 122b3791ede095345f44666691aa9ce5aa7f725a and 093a78d by @janicduplessis and @grabbou.

Any ideas on this?

[gjdycus]

Does anyone know of any workarounds for this?

[satya164]

cc @janicduplessis

[stale]

Hey there, it looks like there has been no activity on this issue recently. Has the issue been fixed, or does it still require the community's attention? This issue may be closed if no further activity occurs. You may also label this issue as "For Discussion" or "Good first issue" and I will leave it open. Thank you for your contributions.

[reime005]

This issue is still present in the latest React Native release (0.57.4)

[ma-pe]

This describes the same behaviour: #21092

[AndrewSouthpaw]

It looks like this commit fixes the issue but it hasn't been released to a tagged version, any chance that'll happen soon? 🙏

[Titozzz]

This commit has been released as part of 0.59 so I'll close the issue.
Please let us know if anything is still not working!

Thanks everyone 😄