[SOLVED] How to retrieve documents from an index in firestore subcollection in Gen App Builder

How to retrieve documents from an index in firestore subcollection in Gen App Builder

I using Firebase as my data store. I have a Firestore data structure where documents in a parent collection ("organizations") contain a subcollection ("rags") that stores text chunks along with their corresponding vector embeddings.

I want to create a retriever that efficiently fetches the most relevant documents from a specific organization's "rags" subcollection.

Here's a simplified version of my current code:

const retrieverConfig = defineFirestoreRetriever({
    name: 'retriever',
    firestore: firestore,
    collection: 'organizations',
    ...options,
    embedder: textEmbeddingGecko
  })

This won't retrieve the vectors from the subcollection since it is only looking at the parent collection 'organizations'.

How do I create a custom retriever to query the subcollection?

Solution

It's likely that you can use the same syntax to locate a subcollection as you would with the Firestore SDK (on any client platform) by providing a delimited path to the subcollection:

collection: 'organizations/DOCID/SUBCOLLECTION'

Where DOCID is the unique document ID in the organizations collection, and SUBCOLLECTION is the name of the nested subcollection under that document.