Query based on grandchild

Question

I have a project returning data from IOT devices in different rooms. The data is set up as:

<firebase_url>
  |-<room_id>
  |  |-<report_id>
  |  |  |-<data>
  |  |
  |  |-<report_id>
  |     |-<data>
  |
  |-<room_id>

I want to be able to query based on info in the <data> but it keeps telling me I need an index. The problem is that the room id's aren't hard coded. They're set from the devices. Is there a way to do this without needing to add an index for every new room added?

In addition to Frank van Puffelen's answer, you can also consider using Cloud Firestore and use a [collection group query](https://firebase.google.com/docs/firestore/query-data/queries#collection-group-query). — Alex Mamo, Mar 06 '23 at 07:23

score 0 · Answer 1 · answered Mar 01 '23 at 19:21

Firebase Realtime Database can order/filter nodes at a path on a value that exists on a fixed, known path under each direct child node.

So in your data structure that means that you can query a specific room for data in the individual reports, but you can't query across all reports of all rooms. If you want that, consider either unnesting the data into a flat list, or creating an additional flat list of the nodes to allow this query.

Also see:

Query based on grandchild

1 Answers1