Firestore: Query by item in array of document

Question

I have 2 collections "photos" and "users" and each document in "users" has one or more photo IDs with an array.

photos > 5528c46b > name: "Photo1"          a1e820eb > name: "Photo2"          32d410a7 > name: "Photo3" 

users > acd02b1d > name: "John", photos: ["5528c46b"]         67f60ad3 > name: "Tom", photos: ["5528c46b", "32d410a7"]         7332ec75 > name: "Sara", photos: ["a1e820eb"]         9f4edcc1 > name: "Anna", photos: ["32d410a7"] 

I want to get all users who have one or more specific photo IDs.

Are there any ways to do that?

Answer 1

See Henry's answer, as we've no made Array Contains queries available.

Unfortunately not yet, although it's on our roadmap.

In the meantime, you'll need to use a map instead, in the form of:

photos: {     id1: true     id2: true } 

Now you can find all users with id1 by filtering by photos.id1 == true.

Read more about querying such sets in the Firebase documentation.