Unexpected onCreate behavior after changing collection path and hot reload

[katopz]

[REQUIRED] Environment info

firebase-tools:
8.7.0

"firebase-admin": "^9.0.0",
"firebase-functions": "^3.9.0",

Platform:
macOS 10.15.5

[REQUIRED] Test case

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

// Admin service account key
const serviceAccount = require('../firebase-admin.staging.key.json')
firebase.initializeApp({
  credential: firebase.credential.cert(serviceAccount)
})

export const watchCreate1 = functions.firestore
  .document('{a}/{b}')
  .onCreate((snap, context) => console.log('watchCreate1:', context.params))

export const watchCreate2 = functions.firestore
  .document('{a}/{b}/{c}/{d}')
  .onCreate((snap, context) => console.log('watchCreate2:', context.params))

console.log('Add /foo/bar')
// tslint:disable-next-line: no-floating-promises
firebase
  .firestore()
  .collection('foo')
  .doc('bar')
  .set({ bar: 'bar' })

[REQUIRED] Steps to reproduce

1. Run above code
2. Get output

   watchCreate1: { a: 'foo', b: 'bar' }
   

3. Clear all data via http://localhost:4006/firestore
4. Change watchCreate1 function to...

   export const watchCreate1 = functions.firestore
     .document('{a}/{b}/{c}/{d}')
     .onCreate((snap, context) => console.log('watchCreate1:', context.params))

   Then save file to trigger nodemon to recompile the code.
5. Get output

   watchCreate1: { a: 'foo', b: 'bar', c: undefined, d: undefined }
   

[REQUIRED] Expected behavior

Judge from second attempt, The first run should return...

watchCreate1: { a: 'foo', b: 'bar' }
watchCreate2: { a: 'foo', b: 'bar', c: undefined, d: undefined }

[REQUIRED] Actual behavior

watchCreate1: { a: 'foo', b: 'bar' }

What I'm trying to do

I'm trying to watch all update in one function but it seem to do able only after changing code and hot reload. e.g.

export const watchCreate = functions.firestore
  .document('{a}/{b}/{c}/{d}/{e}/{f}/{g}/{h}/{i}/{j}/{k}/{l}/{m}/{n}/{o}/{p}/{q}/{r}/{s}/{t}/{u}/{v}/{w}/{x}/{y}/{z}')
  .onCreate((snap, context) => console.log('watchCreate1:', context.params))

Didn't to work at first run but if I change the code and do hot reload it will work as expect.
FYI : I expect { a: 'foo', b: 'bar', c: undefined, d: undefined, ... }
But whenever I restart emu, I will got not thing because {a}/.../{z} didn't match foo/bar.

I know this is sound weird and confuse, I lost an hour to figure this strange behavior anyway.
BTW, I wouldn't know what collection name will be add at root by user, so I've to dynamically watch it as {a}.

[samtstern]

@katopz thanks for the descriptive issue. I think this is actually working as intended, although it's definitely confusing! I think the hot reload is failing to notice the updated trigger definition, which is a bug. However you can't really do what you're trying to do:

If you have this trigger:

functions.firestore.document('{a}/{b}/{c}/{d}').onCreate({ ... });

A write to /foo/bar does NOT match that description. {c} and {d} must be path segments with length >=0 to match.

That said if you're really set on this, you can do:

// Match all writes to top level collections like /foo/bar
functions.firestore.document('{a}/{b}').onCreate({ ... });

// Match all writes to second level collections like /foo/bar/sub/doc
functions.firestore.document('{a}/{b}/{c}/{d}').onCreate({ ... });

// Match all writes to third level collections like /foo/bar/sub/doc/sub/doc
functions.firestore.document('{a}/{b}/{c}/{d}/{e}/{f}').onCreate({ ... });
// etc