How to get multiple references in a firestore snapshot - firebase

Question

I have a firestore collection containing post documents, each document contains a reference to an author (user) and a case document.
How do I get the user and the case in the same onSnapshot?
Here's what I'd like to do with await, but that doesn't seem to be an option with react-native-firebase.
export const firebasePostLooper = (snapshot) => {
let data = [];
snapshot.forEach(async (doc) => {
let newItem = {id: doc.id, ...doc.data()};
if (newItem.author) {
let authorData = await getDoc(newItem.author); // doesn't work with rnfirebase
if (authorData.exists()) {
newItem.userData = {userID: authorData.id, ...authorData.data()};
}
}
if (newItem.case) {
let caseData = await getDoc(newItem.case);
if (caseData.exists()) {
newItem.userData = {userID: caseData.id, ...caseData.data()};
}
}
data.push(newItem);
});
return data;
};
This doesn't work because getDoc() doesn't exist.
So I'm left with using .then()
export const firebasePostLooper = (snapshot) => {
let data = [];
snapshot.forEach((doc) => {
let newItem = {id: doc.id, ...doc.data()};
if (newItem.author) {
newItem.author
.get()
.then((res) => {
newItem.authorData = res.data();
if (newItem.case) {
newItem.case
.get()
.then((caseRes) => {
newItem.caseData = caseRes.data();
data.push(newItem);
})
.catch((err) => console.error(err));
}
})
.catch((err) => console.error(err));
} else {
data.push(newItem);
}
});
return data;
};
This second method doesn't seem to be working, data is empty at the return statement but data.push(newItem) contains the correct document with the 2 referenced documents.

Answer 1

You're returning data before it gets filled inside the promise. You should handle the returning of the data inside a .then() in order to return it after the promise has resolved and not before.
Take a look at this example where if we handle the emptyData object outside the promise chain, we just return the initial value before it has been filled.
let promise = new Promise((resolve, reject)=>{
setTimeout(resolve, 1000, 'foo');
})
let emptyData= [];
let notEmptyData = [];
promise
.then(res=>{
emptyData.push(res);
notEmptyData.push(res);
console.log("Full data: " + notEmptyData) // "Full data: foo"
});
console.log("Empty data: " + emptyData); // "Empty data: "