How to get all subcollection documents with subcollection name as a date? [duplicate] - reactjs

Question

Say I have this minimal database stored in Cloud Firestore. How could I retrieve the names of subCollection1 and subCollection2?
rootCollection {
aDocument: {
someField: { value: 1 },
anotherField: { value: 2 }
subCollection1: ...,
subCollection2: ...,
}
}
I would expect to be able to just read the ids off of aDocument, but only the fields show up when I get() the document.
rootRef.doc('aDocument').get()
.then(doc =>
// only logs [ "someField", "anotherField" ], no collections
console.log( Object.keys(doc.data()) )
)

Answer 1

It is not currently supported to get a list of (sub)collections from Firestore in the client SDKs (Web, iOS, Android).
In server-side SDKs this functionality does exist. For example, in Node.js you'll be after the ListCollectionIds method:
var firestore = require('firestore.v1beta1');
var client = firestore.v1beta1({
// optional auth parameters.
});
// Iterate over all elements.
var formattedParent = client.anyPathPath("[PROJECT]", "[DATABASE]", "[DOCUMENT]", "[ANY_PATH]");
client.listCollectionIds({parent: formattedParent}).then(function(responses) {
var resources = responses[0];
for (var i = 0; i < resources.length; ++i) {
// doThingsWith(resources[i])
}
})
.catch(function(err) {
console.error(err);
});

Answer 2

It seems like they have added a method called getCollections() to Node.js:
firestore.doc(`/myCollection/myDocument`).getCollections().then(collections => {
for (let collection of collections) {
console.log(`Found collection with id: ${collection.id}`);
}
});
This example prints out all subcollections of the document at /myCollection/myDocument

Answer 3

Isn't this detailed in the documentation?
/**
* Delete a collection, in batches of batchSize. Note that this does
* not recursively delete subcollections of documents in the collection
*/
function deleteCollection(db, collectionRef, batchSize) {
var query = collectionRef.orderBy('__name__').limit(batchSize);
return new Promise(function(resolve, reject) {
deleteQueryBatch(db, query, batchSize, resolve, reject);
});
}
function deleteQueryBatch(db, query, batchSize, resolve, reject) {
query.get()
.then((snapshot) => {
// When there are no documents left, we are done
if (snapshot.size == 0) {
return 0;
}
// Delete documents in a batch
var batch = db.batch();
snapshot.docs.forEach(function(doc) {
batch.delete(doc.ref);
});
return batch.commit().then(function() {
return snapshot.size;
});
}).then(function(numDeleted) {
if (numDeleted <= batchSize) {
resolve();
return;
}
// Recurse on the next process tick, to avoid
// exploding the stack.
process.nextTick(function() {
deleteQueryBatch(db, query, batchSize, resolve, reject);
});
})
.catch(reject);
}

Answer 4

This answer is in the docs
Sadly the docs aren't clear what you import.
Based on the docs, my code ended up looking like this:
import admin, { firestore } from 'firebase-admin'
let collections: string[] = null
const adminRef: firestore.DocumentReference<any> = admin.firestore().doc(path)
const collectionRefs: firestore.CollectionReference[] = await adminRef.listCollections()
collections = collectionRefs.map((collectionRef: firestore.CollectionReference) => collectionRef.id)
This is of course Node.js server side code. As per the docs, this cannot be done on the client.