I have a Firebase Cloud Function that assigns a number to a user on onWrite. The following code works but something is wrong because the console logs state Function returned undefined, expected Promise or value.
I'm also not sure how to refer to the root from inside the onWrite so I've created several "parent" entries that refer to each other. I'm sure there is a better way.
onWrite triggers on this:
/users/{uid}/username
The trigger counts the children in /usernumbers and then writes an entry here with the uid and the child count + 1:
/usernumbers/uoNEKjUDikJlkpLm6n0IPm7x8Zf1 : 5
Cloud Function:
'use strict';
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();
exports.setCount = functions.database.ref('/users/{uid}/username').onWrite((change, context) => {
const uid = context.params.uid;
const parent1 = change.after.ref.parent; //uid
const parent2 = parent1.ref.parent; //users
const parent3usernumbers = parent2.ref.parent.child('/usernumbers/');
const parent3usernumbersuid = parent2.ref.parent.child('/usernumbers/'+uid);
parent3usernumbers.once("value")
.then(function(snapshot) {
var a = snapshot.numChildren();
return parent3usernumbersuid.transaction((current) => {
return (a + 1);
}).then(() => {
return console.log('User Number Written', uid, a);
});
});
});
Is there a better way to do this? How can I get the Function Returned Undefined error to go away?
I should also mention it takes a few seconds for the 'usernumber' entry to be written. I'm guessing it's waiting for the function to return something.
Your function have to return a Promise :
exports.setCount = functions.database.ref('/users/{uid}/username').onWrite((change, context) => {
const uid = context.params.uid;
const parent1 = change.after.ref.parent; //uid
const parent2 = parent1.ref.parent; //users
const parent3usernumbers = parent2.ref.parent.child('/usernumbers/');
const parent3usernumbersuid = parent2.ref.parent.child('/usernumbers/'+uid);
return new Promise((resolve, reject) => {
parent3usernumbers.once("value").then(function(snapshot) {
var a = snapshot.numChildren();
return parent3usernumbersuid.transaction((current) => {
return (a + 1);
}).then(() => {
console.log('User Number Written', uid, a);
resolve({uid : uid, a : a})
}).catch(function(e) {
reject(e)
})
});
});
});
Related
How do I get all the comments from the subcollection?
This is mine reusable function to get comments collection.
import { ref, watchEffect } from 'vue';
import { projectFirestore } from '../firebase/config';
const getCollection = (collection, id, subcollection) => {
const comments = ref(null);
const error = ref(null);
// register the firestore collection reference
let collectionRef = projectFirestore
.collection(collection)
.doc(id)
.collection(subcollection);
const unsub = collectionRef.onSnapshot(
snap => {
let results = [];
snap.docs.forEach(doc => {
doc.data().createdAt && results.push(doc.data());
});
// update values
comments.value = results;
error.value = null;
},
err => {
console.log(err.message);
comments.value = null;
error.value = 'could not fetch the data';
}
);
watchEffect(onInvalidate => {
onInvalidate(() => unsub());
});
return { error, comments };
};
export default getCollection;
And this is mine Comments.vue where i passing arguments in setup() function (composition API)
const { comments } = getAllComments('posts', props.id, 'comments');
When i console.log(comments) its null, in snapshot doc.data() is good but somehow results too is empty array even if i push doc.data() to results array and pass it to comments.value.
Can someone help me how to get that subcollection?
This is my Comment.vue component
export default {
props: ['id'],
setup(props) {
const { user } = getUser();
const content = ref('');
const { comments } = getAllComments('posts', props.id, 'comments');
const ownership = computed(() => {
return (
comments.value && user.value && user.value.uid == comments.value.userId
);
});
console.log(comments.value);
}
return { user, content, handleComment, comments, ownership };
},
};
const getCollection = (collection, id, subcollection) => {
const comments = ref(null);
const error = ref(null);
// Firestore listener
return { error, comments };
}
The initial value of comments here is null and since Firebase operations are asynchronous, it can take a while before the data loads and hence it'll log null. If you are using comments in v-for then that might throw an error.
It'll be best if you set initial value to an empty array so it'll not throw any error while the data loads:
const comments = ref([]);
Additionally, if you are fetching once, use .get() instead of onSnapshot()
I'm working on the group functionality of my app where members of the group can add task to a group that they are currently working on. So, when a task is added I want to notify all members using FCM that a task had been added to the group.
EDIT:
The code to add the task to a group is run on the client and works successfully. The purpose of the cloud function is just to send cloud messages to all the members of the group that a task has been added by a particular member.
This is my logic for the cloud function :
1st. As a task can be added to multiple groups at a time I'm using a forEach().
2nd. I'm fetching the uids of the Members in the groups and pushing them into an array(uids) so that later I can retrieve their fcmTokens.
3rd. Running a forEach on the uids to retrieve the fcmTokens.
4th.Sending Cloud message to devices.
But the cloud function doesn't execute as expected.
This my cloud function:
exports.newTaskAdded = functions.https.onCall(async (data, context) => {
const groups = data.groups; //Can be multiple groups hence an array.
const uid = data.uid;
const author = data.author;
const taskId = data.taskId;
const taskTitle = data.taskTitle;
try {
groups.forEach(async group => {
const groupName = group.groupName;
console.log('groupName: ', groupName);
const groupId = groups.groupId;
const membersPromises = [];
membersPromises.push(
admin
.firestore()
.collection('Groups')
.doc(`${groupId}`)
.collection('Members') //Members collection has document for each user with their uid as the document name.
.get(),
);
console.log('memberPromises: ', membersPromises);//Function stops after this.
const membersSnapshot = await Promise.all(membersPromises);
console.log('membersSnapshots', membersSnapshot);
const uids = [];
membersSnapshot.forEach(doc => {
doc.forEach(snap => {
console.log(snap.id);
uids.push(snap.id);
});
});
console.log(uids);
const uidPromises = [];
uids.forEach(uid => {
uidPromises.push(
admin
.firestore()
.collection('Users')
.doc(`${uid}`)
.get(),
);
});
console.log('uidPromises: ', uidPromises);
const tokensSnapshots = await Promise.all(uidPromises);
const notifPromises = [];
tokensSnapshots.forEach(snap => {
console.log(snap.data());
const token = Object.keys(snap.data().fcmTokens);
const payload = {
notification: {
title: `${author} has added a new task to ${groupName}`,
body: `Task Added: ${taskTitle}`,
sound: 'default',
},
};
notifPromises.push(admin.messaging().sendToDevice(token, payload));
});
await Promise.all(notifPromises);
});
} catch (err) {
console.log(err);
}
return {result: 'OK'};
});
This is my log:
As you can see there is no error shown.
Help would be very much appreciated. Thank you
as far as I know, background trigger cloud function should return a promise,right? but what if I want to do nothing in the one of my execution path ?
export const updateDataWhenUserUnattendTheEvent = functions.firestore
.document('events/{eventId}/Attendee/{userId}')
.onDelete((snap, context) => {
const eventID = context.params.eventId
const eventRef = snap.ref.firestore.collection('events').doc(eventID)
const db = admin.firestore()
return db.runTransaction(async t => {
const doc = await t.get(eventRef)
if (doc) {
const eventRankPoint = doc.data().rankPoint
let eventCapacity = doc.data().capacity
return t.update(eventRef,{
isFullCapacity : false,
capacity : eventCapacity + 1,
rankPoint: eventRankPoint - 1
})
} else {
// what should I write in here? empty promise?
return new Promise()
}
})
})
I want to my function worked only if the document is exist. so what should I do ? I write new Promise but .... I don't know what to do actually. thanks in advance
You can just return null if there's no asynchronous work to perform in some code path of your functions. You only truly need a promise if it tracks some async work.
Alternatively, you could return a promise that's resolved immediately with Promise.resolve(null)
Because db.runTransaction is an async function it will return a Promise all the time.
You can drop the else statement and the method will perform as expected because runTransaction will return Promise<void> which is a valid response for Cloud Functions
export const updateDataWhenUserUnattendTheEvent = functions.firestore
.document('events/{eventId}/Attendee/{userId}')
.onDelete((snap, context) => {
const eventID = context.params.eventId;
const eventRef = snap.ref.firestore.collection('events').doc(eventID);
const db = admin.firestore();
return db.runTransaction(async t => {
const doc = await t.get(eventRef);
if (doc) {
const eventRankPoint = doc.data().rankPoint;
let eventCapacity = doc.data().capacity ;
return t.update(eventRef,{
isFullCapacity : false,
capacity : eventCapacity + 1,
rankPoint: eventRankPoint - 1
});
}
});
});
You can also make the onDelete function async which means you can force it to always return a Promise - the below is valid and will exit the function correctly.
export const updateDataWhenUserUnattendTheEvent = functions.firestore
.document('events/{eventId}/Attendee/{userId}')
.onDelete(async (snap, context) => {
// Do Nothing
return;
});
Hello, above is my simple data structure in firebase's realtime db. I'm working on a simple cloud function that will listen to update in a user node 'score' property and update the 'averageScore' field that sits higher up the hierarchy.
Here's my onWrite callback:
.onWrite((change, context) => {
if (!change.before.exists() || !change.after.exists()) {
return null;
}
const beforeScore = parseFloat(change.before.val()['score']);
const afterScore = parseFloat(change.after.val()['score']);
const userRef = change.after.ref;
var promises = [
userRef.parent.parent.child('userCount').once('value'),
userRef.parent.parent.child('averageScore').once('value')
];
return userRef.transaction(() => {
return Promise.all(promises).then((snapshots) => {
const userCount = snapshots[0].val();
const averageScore = snapshots[1].val();
const currentAverage = (( ( averageScore * userCount ) - beforeScore + afterScore ) / userCount ).toFixed(2);
return userRef.parent.parent.child('averageScore').set(currentAverage);
});
});
});
If I update userId 1234's score, the averageScore field is updated correctly per this code. However, the whole user Id node 1234 gets DELETED following this update. This is quite a head scratcher and hoping to get some insight from the community on what I might be doing wrong.
Cheers.
.onWrite((change, context) => {
if ( !change.before.exists() || !change.after.exists()) {
return null;
}
const beforeScore = parseFloat(change.before.val()['score']);
const afterScore = parseFloat(change.after.val()['score']);
const crowdStatsRef = change.after.ref.parent.parent.child('crowdStats');
return Promise.all( [
crowdStatsRef.child('userCount').once('value'),
crowdStatsRef.child('averageScore').once('value')
]).then((snapshots) => {
return crowdStatsRef.transaction((crowdStatsNode) => {
if (crowdStatsNode) {
const userCount = snapshots[0].val();
const averageScore = snapshots[1].val();
const currentAverage = (( ( averageScore * userCount ) - beforeScore + afterScore ) / userCount ).toFixed(2);
crowdStatsNode.score = parseFloat(currentAverage);
}
return crowdStatsNode;
}, (error, committed, snapshot) => {
if (error) {
console.error(error);
}
});
});
});
Misunderstood how transactions worked. The object you're locking onto must be returned in the callback function. Also, a null check in that callback function is essential here.
Examples are noted here:
https://firebase.googleblog.com/2016/01/keeping-our-promises-and-callbacks_76.html
I have observed this behavior occasionally with both onCreate and onDelete triggers.
Both the executions happened for the same document created in firestore. There's only one document there so I don't understand how it could trigger the handler twice. the handler itself is very simple:
module.exports = functions.firestore.document('notes/{noteId}').onCreate((event) => {
const db = admin.firestore();
const params = event.params;
const data = event.data.data();
// empty
});
this doesn't happen all the time. What am I missing?
See the Cloud Firestore Triggers Limitations and Guarantees:
Delivery of function invocations is not currently guaranteed. As the
Cloud Firestore and Cloud Functions integration improves, we plan to
guarantee "at least once" delivery. However, this may not always be
the case during beta. This may also result in multiple invocations
for a single event, so for the highest quality functions ensure that
the functions are written to be idempotent.
There is a Firecast video with tips for implementing idempotence.
Also two Google Blog posts: the first, the second.
Based on #saranpol's answer we use the below for now. We have yet to check if we actually get any duplicate event ids though.
const alreadyTriggered = eventId => {
// Firestore doesn't support forward slash in ids and the eventId often has it
const validEventId = eventId.replace('/', '')
const firestore = firebase.firestore()
return firestore.runTransaction(async transaction => {
const ref = firestore.doc(`eventIds/${validEventId}`)
const doc = await transaction.get(ref)
if (doc.exists) {
console.error(`Already triggered function for event: ${validEventId}`)
return true
} else {
transaction.set(ref, {})
return false
}
})
}
// Usage
if (await alreadyTriggered(context.eventId)) {
return
}
In my case I try to use eventId and transaction to prevent onCreate sometimes triggered twice
(you may need to save eventId in list and check if it exist if your function actually triggered often)
const functions = require('firebase-functions')
const admin = require('firebase-admin')
const db = admin.firestore()
exports = module.exports = functions.firestore.document('...').onCreate((snap, context) => {
const prize = 1000
const eventId = context.eventId
if (!eventId) {
return false
}
// increment money
const p1 = () => {
const ref = db.doc('...')
return db.runTransaction(t => {
return t.get(ref).then(doc => {
let money_total = 0
if (doc.exists) {
const eventIdLast = doc.data().event_id_last
if (eventIdLast === eventId) {
throw 'duplicated event'
}
const m0 = doc.data().money_total
if(m0 !== undefined) {
money_total = m0 + prize
}
} else {
money_total = prize
}
return t.set(ref, {
money_total: money_total,
event_id_last: eventId
}, {merge: true})
})
})
}
// will execute p2 p3 p4 if p1 success
const p2 = () => {
...
}
const p3 = () => {
...
}
const p4 = () => {
...
}
return p1().then(() => {
return Promise.all([p2(), p3(), p4()])
}).catch((error) => {
console.log(error)
})
})
Late to the party, I had this issue but having a min instance solved the issue for me
Upon looking #xaxsis attached screenshot, my function took almost the amount of time about 15 seconds for the first request and about 1/4 of that for the second request