Cloud Firestore function triggers and transactions - how to return a promise correctly - google-cloud-firestore

Question

I have a Cloud Firestore function trigger "onCreate". Depending on the value of a given field, I would like it to either update some documents via a transaction and to copy the created document as a record in Algolia, or to execute a completely different transaction. There are therefore several conditions and I am not sure that I am returning promises correctly, as sometimes the function is not copying the record in Algolia when expected.
I paste a simplified version of the code in case someone can help.
exports.createArticle = functions.firestore.document('articles/{articleId}').onCreate(async (snap, context) => {
const newDocData = snap.data()
if(newDocData) {
const userCreatorId = newDocData.createdBy
const userDocRef = imported.db.collection('users').doc(userCreatorId)
if(newDocData.type === 1) {
newDocData.objectID = newDocData.id
indexAlgolia.saveObject(newDocData)
.then(() => {
console.log('Article saved in Algolia with id:', newDocData.objectID )
})
.catch(err => {
console.log('ERROR while ADDING object inAlgolia:', err)
})
return imported.db.runTransaction(async t => {
// do some work
const userDoc = await t.get(userDocRef)
const userData = userDoc.data()
if (userData && userData.field1 > 0) {
t.update(userDocRef, {field2: true})
}
}).then(result => {
console.log('Transaction success')
}).catch(err => {
console.log('Transaction failure:', err)
})
}
else {
const colOneRef = imported.db.collection('colOne')
colOneRef.where('field2', '==', newDocData.field3).limit(1).get().then(snapshot => {
return imported.db.runTransaction(async t => {
if (snapshot.empty) {
t.update(userDocRef, {field3: false})
}
const decrement = imported.fieldValue.increment(-1)
t.update(userDocRef, {field4: decrement})
}).then(result => {
console.log('Transaction success')
}).catch(err => {
console.log('Transaction failure:', err)
})
}).catch(() => 'Error while querying colOneRef')
}
}
})

Answer 1

When you have multiple async/then calls you canmake them await the result and run them as if they are synchornous but from your code I see that the second doesn't depent on the first one so you can put them in a Promse.all() to make the function finish faster because they will run in parallel. Your code would look like this:
xports.createArticle = functions.firestore
.document("articles/{articleId}")
.onCreate(async (snap, context) => {
const newDocData = snap.data();
if (newDocData) {
const userCreatorId = newDocData.createdBy;
const userDocRef = imported.db.collection("users").doc(userCreatorId);
if (newDocData.type === 1) {
newDocData.objectID = newDocData.id;
const firstPromise = indexAlgolia
.saveObject(newDocData)
.then(() => {
console.log(
"Article saved in Algolia with id:",
newDocData.objectID
);
})
.catch((err) => {
console.log("ERROR while ADDING object inAlgolia:", err);
});
const secondPromise = imported.db
.runTransaction(async (t) => {
// do some work
const userDoc = await t.get(userDocRef);
const userData = userDoc.data();
if (userData && userData.field1 > 0) {
t.update(userDocRef, { field2: true });
}
})
.then((result) => {
console.log("Transaction success");
})
.catch((err) => {
console.log("Transaction failure:", err);
});
return Promise.all([firstPromise, secondPromise]);
} else {
const colOneRef = imported.db.collection("colOne");
return colOneRef
.where("field2", "==", newDocData.field3)
.limit(1)
.get()
.then((snapshot) => {
return imported.db
.runTransaction(async (t) => {
if (snapshot.empty) {
t.update(userDocRef, { field3: false });
}
const decrement = imported.fieldValue.increment(-1);
t.update(userDocRef, { field4: decrement });
})
.then((result) => {
console.log("Transaction success");
})
.catch((err) => {
console.log("Transaction failure:", err);
});
})
.catch(() => "Error while querying colOneRef");
}
return
}
});