Types for Firestore triggered cloud function params?

Question

So here are the available triggers for Firestore cloud functions:

https://firebase.google.com/docs/firestore/extend-with-functions

onCreate

functions.firestore
.document('my-collection/{doc-id}')
.onCreate((snap, context) => { /* ... */ });

onDelete

functions.firestore
.document('my-collection/{doc-id}')
.onDelete((snap, context) => { /* ... */ });

onUpdate

functions.firestore
.document('my-collection/{doc-id}')
.onUpdate((change, context) => { /* ... */ });

onWrite

functions.firestore
.document('my-collection/{doc-id}')
.onWrite((change, context) => { /* ... */ });

I'm converting my project to Typescript. What types should I use for the params change context and snap?

Answer 1

Here are the types:

onCreate:

snapshot: FirebaseFirestore.QueryDocumentSnapshot
context: functions.EventContext

onDelete:

snapshot: FirebaseFirestore.QueryDocumentSnapshot
context: functions.EventContext

onUpdate:

change: functions.Change<FirebaseFirestore.QueryDocumentSnapshot>
context: functions.EventContext

onWrite:

change: functions.Change<FirebaseFirestore.DocumentSnapshot>
context: functions.EventContext

---

More details here and here in the doc.

---

If you are using Typescript, you would import/use like this:

import * as functions from 'firebase-functions'
import * as admin from 'firebase-admin'
...

export const fnSomeCollectionTriggerOnUpdate = 
functions.firestore.document('somecollection/{docId}')
  .onUpdate(async (change: functions.Change<admin.firestore.QueryDocumentSnapshot>,
               context: functions.EventContext) => {
...
}