Firestore query subcollections

Question

I thought I read that you can query subcollections with the new Firebase Firestore, but I don\'t see any examples. For example I have my Firestore setup in the following way

Answer 1

UPDATE 2019

Firestore have released Collection Group Queries. See Gil's answer above or the official Collection Group Query Documentation

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Previous Answer

As stated by Gil Gilbert, it seems as if collection group queries is currently in the works. In the mean time it is probably better to use root level collections and just link between these collection using the document UID's.

For those who don't already know, Jeff Delaney has some incredible guides and resources for anyone working with Firebase (and Angular) on AngularFirebase.

Firestore NoSQL Relational Data Modeling - Here he breaks down the basics of NoSQL and Firestore DB structuring

Advanced Data Modeling With Firestore by Example - These are more advanced techniques to keep in the back of your mind. A great read for those wanting to take their Firestore skills to the next level