Error Undefined is not an object (evaluating 'self.fetch') when importing Realm in React Native

[ataravati]

Environment

React Native Environment Info:
System:
OS: macOS 10.14.2
CPU: (4) x64 Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
Memory: 1.47 GB / 16.00 GB
Shell: 3.2.57 - /bin/bash
Binaries:
Node: 10.14.1 - /usr/local/bin/node
Yarn: 1.12.3 - /usr/local/bin/yarn
npm: 6.4.1 - /usr/local/bin/npm
Watchman: 4.9.0 - /usr/local/bin/watchman
SDKs:
iOS SDK:
Platforms: iOS 12.1, macOS 10.14, tvOS 12.1, watchOS 5.1
Android SDK:
API Levels: 23, 27
Build Tools: 27.0.3, 28.0.3
System Images: android-27 | Intel x86 Atom_64, android-27 | Google APIs Intel x86 Atom
IDEs:
Android Studio: 3.2 AI-181.5540.7.32.5056338
Xcode: 10.1/10B61 - /usr/bin/xcodebuild
npmPackages:
react: 16.5.0 => 16.5.0
react-native: 0.57.2 => 0.57.2
npmGlobalPackages:
react-native-cli: 2.0.1

Description

I get the following error message when importing Realm.

Undefined is not an object (evaluating 'self.fetch')

The issue has already been discussed here and here.

Reproducible Demo

I tried the solution provided in the other posts mentioned under Description, and the issue was resolved temporarily, until I added a reference to one of my mobx-state-tree stores. I did try the same solution in other screens, but that didn't help.

[maxammann]

I can confirm this issue. This happens only in when "Debug JS Remotely" is turned off.

[akvsh-r]

This is likely an issue with the npm & builder cache. You must be having another dependency depending on whatwg-fetch.

Which you can easily check with npm ls whatwg-fetch.

Remove the dependency which is using whatwg-fetch reinstall it. Also clear the builder cache. If you're using expo expo start -c

You'll find some solution stating to do: global.self = global. Which is not really a solution.

[ataravati]

@leaphawk The only dependency is fbjs which is part of react-native. I did manage to resolve the issue by using global.self = global, but as I added more screens to the application the issue came back.

[dulmandakh]

Hello there 👋 this issue doesn't have a repro (which means, a react-native init-ed project with the minimal changes that leads to creating the same issue you are reporting). Unfortunately, I have no way of helping you in a meaningful way – there is no easy way for me to recreate the situation and check that the issue reported is still there when changing the code.

Because of this, we are going to close this issue - but if a repro is shared, we are happy to reopen it 🤗

[dulmandakh]

Please upgrade to 0.59, and also provide reproducible demo.

[maxammann]

In my case this was caused by using the legacy babel plugin "transform-es2015-modules-commonjs".