Question:

Preventing firestore onUpdate cloud functions while using onSnapshot in JS

Problem

I got a question about onSnapshot and cloud functions behavior.

If I use onSnapshot, as far as I understand, it does most locally and then updates with the cloud every 1 sec with a hook. But I have a cloud function functions.firestore.document(...).onUpdate and this one will be called every time of those update hooks if I have like a text field. The function itself is there to check if a type field (typeA,typeB) has been changed, and if so it does some stuff in other collections.

Can I trigger the function somehow manually, like when the subscription is unsubscribed, for example, that would be the best. but then I can't compare using the snap.before/after functionality in the cloud functions?

What would be a good way to handle this?

Here is my cloud function, it updates the parent document if the type field is changed in the updated document. And I don't want to have tons of invocations on OnSnapshot updates

export const incrementCountsOnUpdate = functions.firestore

.document('parent/{parentId}/chiild/{chiildId}')

.onUpdate(async (snap, context) => {

const beforeType = snap.before.data().type

const afterType = snap.after.data().type

if (beforeType === afterType) return

const setRef = snap.before.ref.parent.parent

if (setRef) {

await setRef.update({

[getCounter(beforeType)]: FieldValue.increment(-1),

[getCounter(afterType)]: FieldValue.increment(1)

})