`dev-client` qr code scheme does not work for underscores in app slug

[homburg]

Description of the bug

If you have underscores in your app slug and are using expo-dev-client builds, the pr preview QR codes will not work.

To Reproduce

1. Create expo project with underscore in app slug, eg: https://github.com/homburg/HelloExpo/pull/1
2. Use expo preview action to generate QR code
3. scan QR code to load EAS update in dev-client app build

Expected behavior

Expected the installed dev-client app to load the update from the QR code

Actual behavior

Received a system error message, (paraphrased): "No apps are registered for this url"

Additional context

As seen in this example pull-request: https://github.com/homburg/HelloExpo/pull/1:

The app with app slug: hello_expo generates an url scheme registration in AndroidManifest.xml as <data android:scheme="exp+helloexpo"/> (without underscore).

The preview action generates a qr code with the appScheme query variable set verbatim from the slug config value.

The mismatch between registered scheme and QR code scheme results in an error.

[homburg]

Actually seems like an issue that appScheme for the QR code is generated from the slug value instead of scheme value(s) compared to this: https://github.com/expo/expo-github-action/issues/214#issuecomment-1599383864 unless I'm misunderstanding @byCedric

[byCedric]

Hi @homburg! Thanks for creating this issue. There seems to be some confusion around the slug, schemes, and how they relate to the QR codes from expo/expo-github-action/preview.

• expo-github-action can create two types of QR codes, for expo-go, or dev-build (dev clients) -- we create these URLs here
  • this is resolved and generated in the getVariables method of the expo/expo-github-action/preview code here
• The expo-dev-client package has a plugin that adds a specific exp+<slug>, as scheme, to your project (see plugin code).
  • this plugin actually uses the slug config option, and not the scheme property.

One thing that seems to be missing or incorrect, is that the plugin removes specific characters from this generated exp+<slug> scheme (here). I think this is affecting you right now.

To answer this question:

Actually seems like an issue that appScheme for the QR code is generated from the slug value instead of scheme value(s) compared to this: https://github.com/expo/expo-github-action/issues/214#issuecomment-1599383864 unless I'm misunderstanding @byCedric

Yep, that's correct, because the expo-dev-client plugin uses the slug for the generated exp+helloworld scheme in your Android manifest. I know it's a bit confusing 🙈

[byCedric]

I'll release a patch version soon for v8 that fixes this

[expo-bot]

:tada: This issue has been resolved in version 8.2.1 :tada:

The release is available on:

• 8.2.1
• GitHub release

Your semantic-release bot :package::rocket:

[byCedric]

Let me know if this doesn't fix your issue @homburg! 😄 If you are using expo/expo-github-action/preview@v8, you can just rerun everything. The tag has been updated.

[homburg]

Thanks @byCedric that fixes my QR codes!

And thanks for the great explanation. Makes sense that dev-client scheme is independent of scheme config (by using the app slug)

[byCedric]

Awesome, glad we could resolve it fast. And again, sorry for the confusing property names.