Can I retrieve documents of same subcollection in different collections with the same name, using Firestore?

Question

I'm working on an Android app and I use Firestore to store my data. I have a collection of Users, and every user has a subcollection called Posts. Is there any way to retrieve all posts from all users to show them on my apps feed?

Answer 1

Is there any way to retrieve all posts from all users to show them on my apps feed?

Sure, it is. You need to use collection group queries:

Use a collection group query to retrieve documents from a collection group instead of from a single collection. In code should look like this:

FirebaseFirestore rootRef = FirebaseFirestore.getInstance();
rootRef.collectionGroup("Posts").get().addOnCompleteListener(/* ... */);

Using the above code, you'll be able to get all Post objects that exist within all subcollections named Posts.

Answer 2

You will want to use a collection group query to get all the documents from all subcollections with the same name. For example:

db.collectionGroup("Posts").get()