Develop Reference

My firebase function update document takes MINUTES to execute the first time

I am developping an app to order food online. As backend service I am using firestore to store the data and files. The user can order dishes and there are limited stocks. So every time a user order a dish and create a basket I update the stock of the corresponding ordered dishes. I am using a firebase function in order to perform this action. To be honest it is the first I am creating firebase function.
Into the Basket object, there is a list of ordered Dishes with the corresponding database DishID. When the basket is created, I go through the DishID list and I update the Quantity in the firestore database. On my local emulator it works perfectly and very fast. But online it takes minutes to perform the first update. I can deal with some seconds. Even if it takes a few seconds (like for cold restart) it's okay. But sometimes it can take 3 minutes and someone else can order a dish during this time.
Here is my code:
//Update the dishes quantities when a basket is created
exports.updateDishesQuantity = functions.firestore.document('/Baskets/{documentId}').onCreate(async (snap, context) => {
try{
//Get the created basket
const originalBasket = snap.data();
originalBasket.OrderedDishes.forEach(async dish => {
const doc = await db.collection('Dishes').doc(dish.DishID);
console.log('Doc created');
return docRef = doc.get()
.then((result) =>{
console.log('DocRef created');
if(result.exists){
console.log('Result exists');
const dishAvailableOnDataBase = result.data().Available;
console.log('Data created');
const newQuantity = { Available: Math.max(dishAvailableOnDataBase - dish.Quantity, 0)};
console.log('Online doc updated');
return result.ref.set(newQuantity, { merge: true });
}else{
console.log("doc doesnt exist");
}
})
.catch(error =>{
console.log(error);
return null;
});
});
}catch(error){
console.log(error);
}
});
I have a couple of logs output to debug the outputs on the server. It's the doc.get() function that takes 2 minutes to execute as you can see on the logger below:
Firebase logger
Thanks for your help,

Thansk for your help. I just edited a little bit your code to make it work. I post my edited code. Thanks a lot, now it takes just 4 seconds to update the quantities.
Kid regards
//Update the dishes quantities when a basket is created
exports.updateDishesQuantity = functions.firestore.document('/Baskets/{documentId}').onCreate(async (snap, context) => {
try {
//Get the created basket
const originalBasket = snap.data();
const promises = [];
const quantities = [];
originalBasket.OrderedDishes.forEach(dish => {
promises.push(db.collection('Dishes').doc(dish.DishID).get());
quantities.push(dish.Quantity);
});
const docSnapshotsArray = await Promise.all(promises);
console.log("Promises", promises);
const promises1 = [];
var i = 0;
docSnapshotsArray.forEach(result => {
if (result.exists) {
const dishAvailableOnDataBase = result.data().Available;
const newQuantity = { Available: Math.max(dishAvailableOnDataBase - quantities[i], 0) };
promises1.push(result.ref.set(newQuantity, { merge: true }));
}
i++;
})
return Promise.all(promises1)
} catch (error) {
console.log(error);
return null;
}
});

You should not use async/await within a forEach() loop, see "JavaScript: async/await with forEach()" and "Using async/await with a forEach loop".
And since your code executes, in parallel, a variable number of calls to the asynchronous Firebase get() and set() methods, you should use Promise.all().
You should refactor your Cloud Function along the following lines:
//Update the dishes quantities when a basket is created
exports.updateDishesQuantity = functions.firestore.document('/Baskets/{documentId}').onCreate(async (snap, context) => {
try {
//Get the created basket
const originalBasket = snap.data();
const promises = [];
originalBasket.OrderedDishes.forEach(dish => {
promises.push(db.collection('Dishes').doc(dish.DishID).get());
});
const docSnapshotsArray = await Promise.all(promises);
const promises1 = [];
docSnapshotsArray.forEach(snap => {
if (result.exists) {
const dishAvailableOnDataBase = result.data().Available;
const newQuantity = { Available: Math.max(dishAvailableOnDataBase - dish.Quantity, 0) };
promises1.push(result.ref.set(newQuantity, { merge: true }));
}
})
return Promise.all(promises1)
} catch (error) {
console.log(error);
return null;
}
});
Note that instead of looping and calling push() you could use the map() method for a much concise code. However, for SO answers, I like the clarity brought by creating an empty array, populating it with a forEach() loop and passing it to Promise.all()...
Also note that since you are updating quantities in a basket you may need to use a Transaction.

Retrieve multiple users info from firebase auth using Node js

I am using Firebase authentication to store users. I have two types of users: Manager and Employee. I am storing the manager's UID in Firestore employee along with the employee's UID. The structure is shown below.
Firestore structure
Company
|
> Document's ID
|
> mng_uid: Manager's UID
> emp_uid: Employee's UID
Now I want to perform a query like "Retrieve employees' info which is under the specific manager." To do that I tried to run the below code.
module.exports = {
get_users: async (mng_uid, emp_uid) => {
return await db.collection("Company").where("manager_uid", "==", mng_uid).get().then(snaps => {
if (!snaps.empty) {
let resp = {};
let i = 0;
snaps.forEach(async (snap) => {
resp[i] = await admin.auth().getUser(emp_uid).then(userRecord => {
return userRecord;
}).catch(err => {
return err;
});
i++;
});
return resp;
}
else return "Oops! Not found.";
}).catch(() => {
return "Error in retrieving employees.";
});
}
}
Above code returns {}. I tried to debug by returning data from specific lines. I got to know that the issue is in retrieving the user's info using firebase auth function which I used in forEach loop. But it is not returning any error.
Thank you.

There are several points to be corrected in your code:
You use async/await with then() which is not recommended. Only use one of these approaches.
If I understand correctly your goal ("Retrieve employees' info which is under the specific manager"), you do not need to pass a emp_uid parameter to your function, but for each snap you need to read the value of the emp_uid field with snap.data().emp_uid
Finally, you need to use Promise.all() to execute all the asynchronous getUser() method calls in parallel.
So the following should do the trick:
module.exports = {
get_users: async (mng_uid) => {
try {
const snaps = await db
.collection('Company')
.where('manager_uid', '==', mng_uid)
.get();
if (!snaps.empty) {
const promises = [];
snaps.forEach(snap => {
promises.push(admin.auth().getUser(snap.data().emp_uid));
});
return Promise.all(promises); //This will return an Array of UserRecords
} else return 'Oops! Not found.';
} catch (error) {
//...
}
},
};

save method in mongodb/mongoose

This is my first question here. I tried to save document in my collection, but it doesn't work. Response of function is exactly like I want, but it doesn't save in my db. In another controller (createRoom) foundUser.save() it works, but in this controller it doesn't. Thanks in advance!
I am using mongodb/mongooose and express.
const removeRoom = async (req,res,next) => {
const {roomId, userData} = req.body;
const { userId, token } = userData;
let foundUser;
let updatedRooms;
let indexOfNamespaces;
try {
foundUser = await User.findById(userId)
foundUser.namespaces.forEach((ns,i1)=>{
updatedRooms = ns.rooms.filter((room,i2) => {
if(room.id === roomId){
indexOfNamespaces = i1;
}
return room.id !== roomId
})
})
foundUser.namespaces[indexOfNamespaces].rooms = updatedRooms;
console.log(foundUser);
await foundUser.save();
} catch (err) {
console.log(err);
const error = new HttpError('Sth went wrong [removeRoom]', 500);
return next(error);
}
res.status(201).json({updatedNamespaces: foundUser.namespaces});
}

Mongoose does some optimizations where it will only actually save a field if it "changes". In this case you are modifyting an array, but the array is still the "same" array as in it still === (equals) the previous array. You need to use a new array to replace namespaces.
For example:
foundUser.namespaces = [
...foundUser.namespaces.slice(0, indexOfNamespaces),
{ ...foundUser.namespaces[indexOfNamespaces], rooms: updatedRooms },
...foundUser.namespaces.slice(indexOfNamespaces + 1)
]
Now, when you save Mongoose will see a "new" array that !== (does not equal) the previous array because it is a new instance and it will save it.

Cloud Functions for Firebase: how to use a Transaction promise?

I am trying to write a function in Cloud Functions that triggers every time a user gets created and which then saves that user into a list of users and finally increments a user counter.
However I am not sure if I am using promises correctly.
exports.saveUser = functions.auth.user().onCreate(event => {
const userId = event.data.uid
const saveUserToListPromise = db.collection("users").doc(userId).set({
"userId" : userId
})
var userCounterRef = db.collection("users").doc("userCounter");
const transactionPromise = db.runTransaction(t => {
return t.get(userCounterRef)
.then(doc => {
// Add one user to the userCounter
var newUserCounter = doc.data().userCounter + 1;
t.update(userCounterRef, { userCounter: newUserCounter });
});
})
.then(result => {
console.log('Transaction success!');
})
.catch(err => {
console.log('Transaction failure:', err);
});
return Promise.all([saveUserToListPromise, transactionPromise])
})
I want to make sure that even if many users register at once that my userCounter is still correct and that the saveUser function won't be terminated before the transaction and the save to the list has happened.
So I tried this out and it works just fine however I don't know if this is the correct way of achieving the functionality that I want and I also don't know if this still works when there are actually many users triggering that function at once.
Hope you can help me.
Thanks in advance.

The correct way to perform multiple writes atomically in a transaction is to perform all the writes with the Transaction object (t here) inside the transaction block. This ensures at all of the writes succeed, or none.
exports.saveUser = functions.auth.user().onCreate(event => {
const userId = event.data.uid
return db.runTransaction(t => {
const userCounterRef = db.collection("users").doc("userCounter")
return t.get(userCounterRef).then(doc => {
// Add one user to the userCounter
t.update(userCounterRef, { userCounter: FirebaseFirestore.FieldValue.increment(1) })
// And update the user's own doc
const userDoc = db.collection("users").doc(userId)
t.set(userDoc, { "userId" : userId })
})
})
.then(result => {
console.info('Transaction success!')
})
.catch(err => {
console.error('Transaction failure:', err)
})
})

Remove node from Firebase with Functions

I'm trying to remove a node from Firebase using cronjob and i have this function but when it gets executed I get an error saying "Error: could not handle the request" and the log says: "database is not defined"
This is my function:
exports.cleanStatsOnRequest = functions.https.onRequest((req, res) => {
const ref1 = firebase.database.ref;
const dbref = ref1.child(`/dailystats`);
console.log('removing dailystats');
return dbref.remove
.then(() => {
res.send('dailystats removed');
})
.catch(error => {
res.send(error);
});
});
What am I doing wrong? What is the right way to define the database?

You need to use the Firebase Admin SDK to access the Realtime Database from an HTTP trigger Cloud Function. This documentation shows you how to read from the database. This example shows writing to the database, which would be similar to deleting.

Try this. database,ref and remove are functions. Read this guide.
Also you should not return dbref.remove() as remove() will return a promise.
exports.cleanStatsOnRequest = functions.https.onRequest((req, res) => {
const ref1 = firebase.database().ref(); // changes here
const dbref = ref1.child('/dailystats');
console.log('removing dailystats');
return dbref.remove() // changes here
.then(() => {
res.send('dailystats removed');
})
.catch(error => {
res.send(error);
});
});