[React Native] Fix BlobManager import

[stevensJourney]

Overview

Users have recently reported errors of the form

Exception: require(_dependencyMap[11], "rea(...)/BlobManager").createFromOptions is not a function (it is undefined)

when CRUD uploads were completed.

The BlobManager is used by the react-native-fetch-api package to parse HTTP request responses. The error here seems to be caused by the SDK making a call to the PowerSync service's write-checkpoint2.json endpoint after completing CRUD uploads.

Users confirmed that using the Expo implementation for fetch resolves the issue. See this POC #591.

Expo's fetch implementation is great, but it is included directly in the expo NPM package. Bare React Native users unfortunately do not have the option of using this fix. Conditional require/import statements are also not handled very well in Metro currently. Attempting to conditionally require expo/fetch can print an error message to the console for non Expo users.

The true root cause of this issue seems to be due to the React Native package gradually shifting to ESM exports. The BlobManager was recently converted to an ESM export https://github.com/facebook/react-native/pull/48761/files. Our Rollup config targets a CommonJS output which converts the import in react-native-fetch-api to a require statement. In some project environments, the require can resolve to an object of the form:

{
    _esModule: true,
    default: BlobManager
}

While we expect BlobManager to directly be returned. Our code then tries to access createFromOptions on the result, but this is undefined due to the ES module wrapper structure.

The fix here is to vendor a small wrapper for BlobManager which checks the result of requiring the BlobManager.

Testing

This was tested in a bare React Native App and in the Expo Supabase demo.

[changeset-bot]

🦋 Changeset detected

Latest commit: 76d5b61

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@powersync/react-native	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR