`track` deletes traits in @segment/analytics-next

[jonathanj]

This code deletes the traits property for "track" events, but I'm not sure I understand why. I can't seem to find any documentation that explains why this would be desirable.

I'm implementing a custom plugin that injects traits into events other than identify because our analytics team is having some difficulty when these events end up at the Mixpanel destination and this information is missing. We have implemented the same behaviour for the React Native client, which doesn't seem to suffer from the issue of traits being purged for track events.

Is there a reason why traits would be deleted from track but not from screen/page? Is my intended usage an anti-pattern?

[chenxzhang]

Hey @jonathanj,
User traits are not standard fields for a Track event, so this is an expected behavior.
Identify calls are designed to carry user-level data, via traits, while track events are meant to capture action-level data, using properties. https://segment.com/docs/connections/spec/

The section here also calls out that user Traits are not standard fields for a Track event. You could try to inject the traits under context.traits, but it is still recommended to use identify calls for these.

Regarding the note on React Native, the behavior you observed in React Native is not standardized at Segment.