Firestore and Auto Increment Ids

Solution 1:

There is no built-in auto-increment operator in Firestore. If you want something like that, you will have to build it yourself.

This typically involves keeping track of the latest ID you've used in a document in a well-known location, and then reading-and-updating that document from the client in a transaction.

But do seriously consider whether you can't use Firestore's built-in identifiers, as there are many reasons why Firestore comes with those built-in instead of having an auto-increment operator.

I highly recommend checking out some of these related questions:

• Incrementing Number as Firestore Document Name?
• Firestore generated key versus custom key in a collection?
• How to create auto incremented key in Firebase? (about Firebase's other database, but the reasons are largely the same)

And this page in the Firestore documentation in distributed counters.