the unnest "{as}" produced the child key "{k...

Warnings reference › router:unnest-duplicate-key

Identifier

router:unnest-duplicate-key

Raised by

Data Router

Since

1.84.0

What happened

Two elements of one parent's nested array resolved to the same child key - a duplicated id under a key: 'id' spec, most often. The router is last-writer-wins in the array's source order: the later child's row stands, the earlier is overwritten, rather than collecting or throwing. Warned once per router, not per parent.

The fix

Make the child key (or the array's own ids) unique within each parent, or switch to the default index key.

The smallest fix

addSource('company', { unnest: [{ path: 'addresses', as: 'address', key: 'id', parentKey: 'companyId' }] })

Reference

Covered in full at the API reference.