FlatList requires string as key

[James2516]

• [-] I have reviewed the documentation
• [-] I have searched existing issues
• [-] I am using the latest React Native version

Environment

Environment:
OS: macOS Sierra 10.12.6
Node: 9.8

Packages: (wanted => installed)
react: 16.3.1 => 16.3.1
react-native: 0.55.2 => 0.55.2

Expected Behavior

In a recent update, FlatList API is changed to require strings as keys.

Why is this breaking change implemented?
Many apps use an unique number id (eg. user id, item id) as the key.
Shouldn't any necessary casting be done internally within RN rather than requiring apps to do it?

The API change also makes the key requirement in FlatList inconsistent (more stringent) with keys used in array of components produced by map etc.

[react-native-bot]

Thanks for posting this! It looks like your issue may be missing some necessary information. Can you run react-native info and edit your issue to include these results under the Environment section?

Thank you for your contributions.

[hramos]

The reasoning behind this has been covered in #18291. In short, using an index as a key is an anti-pattern. I don't think changing this back is something that would be considered.

[James2516]

@hramos but I'm not using index as key, I'm using unique item integer id (from database) which is the correct way.