Firestore sub-collections with nonexistent parents are not showing in emulator

[REQUIRED] Environment info

firebase-tools: 8.4.0

Platform: macOS 10.15.4

[REQUIRED] Test case

I’ve found that when having nested collections in Firestore, they don’t display on the web interface of the emulator unless parent documents contain data.

[REQUIRED] Steps to reproduce

// create some data in a nested collection without data in the document

db.collection('stripe')
.doc('6tSfMgrOCEOi3kj0IHRivd0ZCgX2')
.collection('subscriptions')
.doc('sub_123456789').set({
    status: "active"
})

[REQUIRED] Expected behavior

On the production version of the data viewer, it displays empty documents in italics (to designate that there is no fields but sub-collections exist). Image below.

[REQUIRED] Actual behavior

There is nothing to display on the UI and I cannot access child collections. If I set some dummy data on a document, the row will appear.

[yuchenshi]

I’ve escalated this internally as b/152785133 and we’re actively trying to staff this fix. In the meantime, feel free to send us a Pull Request.

[4mitabh]

This is not merely an emulator UI issue.

In certain cases, the behavior of writes is different between emulators and production.

Steps to reproduce:

Perform the following write operation, on em empty database.

db.collection('one')
.doc('two')
.collection('three')
.doc('four').set({
    status: "active"
})

Expected behavior

1. An empty document 'two., with a collection ‘three’ is created. This works perfectly in production.
2. Reads to path “/one/two” should succeed .

Actual behavior:

1. Document ‘two’ is not created in the emulated database.
2. Reads to path “/one/two” fail. Document.exists returns false.