如何在一次通话中获取 Firebase 中的子集合的子集合

Question

I have a firebase schema that look like this: posts > posts(documents) > comments > comments(collections) > replies > replies(documents)

const allComments = await firebase
  .collection('posts')
  .doc(params.slug as string)
  .collection('comments')
  .orderBy("date", "desc")
  .get()

if i tried to get the reply like this:

const allComments = await firebase
  .collection('posts')
  .doc(params.slug as string)
  .collection('comments')
  .doc("some_random_id")
  .collection('reply')
  .get()

i will get only the reply, which is not the desired output. i need to get each reply of each comment in one call. so the returned object would be every comment, and each comment contains an object of replies.

Answer 1

Firestore queries are "shallow", and only return documents immediately within the collection being queried. They don't consider any documents from subcollections. To get documents from subcollections, you would need to make another query for each subcollection.

It might be better to simply put all the comments and replies in a single collection, mark them each with a boolean indicating if it's a reply or not, and use that as a filter if needed on the query. The size of the collection will not have any impact on performance.