Firebase firestore how to get reference data without additional request?

Question

When I have fetched places that we can see in screenshot below, I need get their data, but it's reference to data, I can get the data without additional request like place.ref.data()? If I have 30 places, should I make 30 requests, really? I use react native and the ref object has type DocumentReference https://rnfirebase.io/docs/v3.1.x/firestore/reference/DocumentReference

You'll need to load those references explicitly from your code. Also see https://stackoverflow.com/a/46570119/209103 — Frank van Puffelen, Dec 21 '17 at 15:22
I have exactly the same problem. I am looking for a "populate" kind of an option when I fetch the original document, so the the inner reference field comes pre populated. If anyone could point us in the right direction that would be really helpful! — Harshil Shah, Dec 22 '17 at 15:21

Frederiko Ribeiro · Answer 1 · 2021-07-20T10:26:34.003

You need to create your own populate method.

Here's one example I made where my collection eventSchedule has references to events, then I have the array of events and I want to get the events from each eventSchedule... That's how I did:


   
    ...
    const docRef = db.collection("eventSchedule").doc(dayName);

    try {
        const doc = await docRef.get();

        if (doc && doc.exists) {
            const eventSchedule = doc.data();

            if (eventSchedule.activeEvents) {
                const activeEventsRefs = eventSchedule.activeEvents;
                eventSchedule.activeEvents = [];

                await activeEventsRefs.reduce(
                    async (promise: any, event: any) => {
                        await promise;
                        const childDoc = await event.get();

                        if (childDoc) {
                           eventSchedule.activeEvents.push(childDoc.data());
                        }
                    },
                    Promise.resolve()
                );
            }
        } else {
            logMessage += `No docs found for eventSchedule for today - ${dayName}`;
        }
    } catch (error) {
        logMessage += `Error getting document ${JSON.stringify(error)}`;
    }

So I used reducer to handle the promises. It works like a charm and it was the simplest "manual" way of doing this.

Also if you use React + Redux + Firebase, you can check the library react-redux-firebase that already implements a lot of stuff including the populate that is, similar to the MongoDB populate and the SQL Join: http://react-redux-firebase.com/docs/populate.html

Firebase firestore how to get reference data without additional request?

1 Answers1