Thanks so much for sharing feedback! In this scenario, your collection is "purchases" and there's a "buyerId" field in a purchase document? And you want to get

Thanks so much for sharing feedback! In this scenario, your collection is "purchases" and there's a "buyerId" field in a purchase document? And you want to get the email from buyerId? If buyerId is a uid, you can do another query to get the user document from uid and get the email address from that. I may be misunderstanding the question.