I'm using Firebase Cloud Functions to delete old nodes inside the Firebase Database. Almost 1 month ago I asked a similar question in which the problem was that the values were in seconds instead of milliseconds, but the problem persists. How to fix this problem?
My index.js:
'use strict';
var functions = require('firebase-functions');
var admin = require('firebase-admin');
admin.initializeApp();
// Cut off time. Child nodes older than this will be deleted.
const CUT_OFF_TIME = 30000; // 30 seconds in milliseconds.
/**
* This database triggered function will check for child nodes that are older than the
* cut-off time. Each child needs to have a `timestamp` attribute.
*/
exports.deleteOldItems = functions.database.ref('/posts/{id1}/{id2}/timestamp').onWrite(async (change) => {
var ref = change.after.ref.parent; // reference to the parent
var now = Date.now();
var cutoff = now - CUT_OFF_TIME;
var oldItemsQuery = ref.orderByChild('timestamp').endAt(cutoff);
var snapshot = await oldItemsQuery.once('value');
// create a map with all children that need to be removed
var updates = {};
snapshot.forEach(child => {
updates[child.key] = null;
});
// execute all updates in one go and return the result to end the function
return ref.update(updates);
});
and my database struture
"posts" : {
"38d1d0aa-d774-4a69-a78e-44d02b285669" : {
"-LggzAxeAYXF7tOav_vF" : {
"timestamp" : 1559827888988
}
},
"58fe50ae-db93-4a22-996f-7a28d82583ba" : {
"-Lggze2bvHZx2gJeM8OA" : {
"timestamp" : 1559828012239
}
}
},
Related
I'm trying to write an application using firebase. I want to store JSON search objects in searches/ and a reference to each one of them in a table belonging to the user that made the search. Here's my attempt:
var firebase = require("firebase");
firebase.initializeApp(firebaseConfig);
var database = firebase.database();
/*
* Inserts a search into the database
*/
this.addSearchToDB = function(positive, negative, neutral){
let today = new Date();
let dateCreated = today.getFullYear()+"-"+(today.getMonth()+1)+"-"+today.getDate();
var search = {
"query": searchInput,
"location": location,
"until": date,
"dateCreated": dateCreated,
"amount": tweetAmount,
"positive": positive,
"negative": negative,
"neutral": neutral
};
//setup of path to reference the data
var searchesRef = database.ref("searches");
var newSearchKey = searchesRef.push(search).key;
console.log("newSearchRef key:");
console.log(newSearchKey);
let user = firebase.auth().currentUser;
let uid = user.uid;
console.log("Curr user id: "+uid);
let userRef = database.ref("users/"+uid);
let currUserSearches;
userRef.once("value").then( (value) => {
currUserSearches = value;
});
console.log("Current user searches");
console.log(currUserSearches);
if (currUserSearches === undefined)
currUserSearches = [];
currUserSearches.push(newSearchKey);
userRef.set(currUserSearches).then( () => {
database.ref("users/"+uid).once("value").then((value)=>{
console.log(value.val());
});
});
}
On the first insert, this happens:
I get a newSearchKey (logs successfully to console)
I get the user id of the currentUser (logs successfully to console)
currUserSearches is undefined. (logs undefined to console)
In the userRef.set() callback, a list containing newSearchKey is found and printed to the console.
This is all good. It is what I would expect of the first insert. BUT, when I insert again, the exact same procedure repeats itself, meaning that currUserSearches is once again undefined. This is of course wrong. currUserSearches should contain that key that I just inserted. But it seems like it's forgotten what I inserted.
What is going on here, and how can I achieve the behaviour I want?
This is because all queries (read and write) to the Firebase database are asynchronous. The console.log #3 is executed before the userRef.once("value") returns a result.
You should chain the promises, as follow:
let userRef = database.ref("users/"+uid);
let currUserSearches;
userRef.once("value")
.then( (value) => {
currUserSearches = value;
if (currUserSearches === undefined)
currUserSearches = [];
currUserSearches.push(newSearchKey);
return userRef.set(currUserSearches);
})
.then( () => {
return database.ref("users/"+uid).once("value"); // <- Actually could be userRef.once("value")
})
.then((value)=>{
console.log(value.val());
});
Every minute I have a script that push a new record in my firebase database.
What i want is delete the last records when length of the list reach a fixed value.
I have been through the doc and other post and the thing I have found so far is something like that :
// Max number of lines of the chat history.
const MAX_ARDUINO = 10;
exports.arduinoResponseLength = functions.database.ref('/arduinoResponse/{res}').onWrite(event => {
const parentRef = event.data.ref.parent;
return parentRef.once('value').then(snapshot => {
if (snapshot.numChildren() >= MAX_ARDUINO) {
let childCount = 0;
let updates = {};
snapshot.forEach(function(child) {
if (++childCount <= snapshot.numChildren() - MAX_ARDUINO) {
updates[child.key] = null;
}
});
// Update the parent. This effectively removes the extra children.
return parentRef.update(updates);
}
});
});
The problem is : onWrite seems to download all the related data every time it is triggered.
This is a pretty good process when the list is not so long. But I have like 4000 records, and every month it seems that I screw up my firebase download quota with that.
Does anyone would know how to handle this kind of situation ?
Ok so at the end I came with 3 functions. One update the number of arduino records, one totally recount it if the counter is missing. The last one use the counter to make a query using the limitToFirst filter so it retrieve only the relevant data to remove.
It is actually a combination of those two example provided by Firebase :
https://github.com/firebase/functions-samples/tree/master/limit-children
https://github.com/firebase/functions-samples/tree/master/child-count
Here is my final result
const MAX_ARDUINO = 1500;
exports.deleteOldArduino = functions.database.ref('/arduinoResponse/{resId}/timestamp').onWrite(event => {
const collectionRef = event.data.ref.parent.parent;
const countRef = collectionRef.parent.child('arduinoResCount');
return countRef.once('value').then(snapCount => {
return collectionRef.limitToFirst(snapCount.val() - MAX_ARDUINO).transaction(snapshot => {
snapshot = null;
return snapshot;
})
});
});
exports.trackArduinoLength = functions.database.ref('/arduinoResponse/{resId}/timestamp').onWrite(event => {
const collectionRef = event.data.ref.parent.parent;
const countRef = collectionRef.parent.child('arduinoResCount');
// Return the promise from countRef.transaction() so our function
// waits for this async event to complete before it exits.
return countRef.transaction(current => {
if (event.data.exists() && !event.data.previous.exists()) {
return (current || 0) + 1;
} else if (!event.data.exists() && event.data.previous.exists()) {
return (current || 0) - 1;
}
}).then(() => {
console.log('Counter updated.');
});
});
exports.recountArduino = functions.database.ref('/arduinoResCount').onWrite(event => {
if (!event.data.exists()) {
const counterRef = event.data.ref;
const collectionRef = counterRef.parent.child('arduinoResponse');
// Return the promise from counterRef.set() so our function
// waits for this async event to complete before it exits.
return collectionRef.once('value')
.then(arduinoRes => counterRef.set(arduinoRes.numChildren()));
}
});
I have not tested it yet but soon I will post my result !
I also heard that one day Firebase will add a "size" query, that is definitely missing in my opinion.
In the code below I am trying to use a cloud function to do a multiple update of setting some of my fields to a new value, but it just results to overwriting each of the nodes. I don't really understand this behavior, cos I just needed a simple update.
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
exports.onJobBid_Status = functions.database
.ref("/JobBids/{jobId}/{bidId}/status")
.onWrite((event) => {
let newStatus = event.data.val();
let updates = {};
updates["/Jobs/" + event.params.jobId] = { status: newStatus, };
updates["/Users/" + event.params.bidId + "/JobBids/" + event.params.jobId] = { status: newStatus, level:"4", color:"green" };
return admin.database().ref().update(updates);
});
When you call update, the Firebase server:
Loops through the properties/paths of the updates.
For each property/path, performs a set() operation.
So while you can update specific paths, at each path the operation is a regular set(). This means it replaces the data under each path.
The solution is to have the entire path to the lowest-level property in your key. So in your case:
let updates = {};
updates["/Jobs/" + event.params.jobId+"/status"] = newStatus;
let jobPath = "/Users/" + event.params.bidId + "/JobBids/" + event.params.jobId;
updates[jobPath+/status"] = newStatus;
updates[jobPath+/level"] = "4"; // consider storing this as a number
updates[jobPath+/color"] = "green" ;
With these updates, you will only replace the values of the status, level and color properties.
This question already has an answer here:
Illegal return statement in JavaScript
(1 answer)
Closed 5 years ago.
A 'days' node with more than 1 child isn't getting removed. How can I fix this issue?
Here's my code below (originally from here):
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
const defaultDatabase = admin.database();
exports.deleteOldItems = functions.database.ref('/path/to/items/{pushId}')
.onWrite(event => {
var ref = event.data.ref.parent; // reference to the items
var now = Date.now();
var cutoff = now - 2 * 60 * 60 * 1000;
var oldItemsQuery = ref.orderByChild('timestamp').endAt(cutoff);
return oldItemsQuery.once('value', function(snapshot) {
// create a map with all children that need to be removed
var updates = {};
snapshot.forEach(function(child) {
updates[child.key] = null
});
// execute all updates in one go and return the result to end the function
return ref.update(updates);
}).then(function() {;
const theRef = event.data.ref;
const collectionRef = theRef.parent.child('days');
return collectionRef;
collectionRef.once('value').then(messagesData => {
if(messagesData.numChildren() > 1) {
let updates = {};
updates['/days'] = null;
return defaultDatabase.ref().update(updates); // 'days' doesn't get removed even if it has more than 1 child (as in the image)!
}
})
});
});
Data structure:
To make your code work, just replace the following line :-
return collectionRef;
collectionRef.once('value').then(messagesData => {
with the following :-
return collectionRef.once('value').then(messagesData => {
The reason this works is that the return statement in return collectionRef prevents further code from executing. Instead of that, you must return the promise(action) as is being done in my suggested replacement.
This should solve your problem right now, but as Frank van Puffelen mentioned in his comments, learning the concepts of promises would tremendously help you in the future!
I have a simple presence user-count set up for firebase based on their example. The problem is that it relies on removing counts on disconnect. However, firebase seems to go down every 2 months and removes the ondisconnect handlers. This means that over time the counts get more and more wrong. Is there any way to fix this?
ty.Presence = function() {
this.rooms = {}
this.presence = fb.child('presence')
this.connectedRef = fb.child('.info/connected');
if (!localStorage.fb_presence_id) {
localStorage.fb_presence_id = Math.random().toString(36).slice(2)
}
this.browserID = localStorage.fb_presence_id
var first = false
}
ty.Presence.prototype.add = function(roomID, userobj) {
var self = this
var userListRef = this.presence.child(roomID)
// Generate a reference to a new location for my user with push.
var obj = {
s: "on",
id: this.browserID
}
if (userobj) {
obj.u = {
_id: userobj._id,
n: userobj.username
}
if (userobj.a) {
obj.u.a = userobj.a
}
}
var myUserRef = userListRef.push(obj)
this.rooms[roomID] = myUserRef
this.connectedRef.on("value", function(isOnline) {
if (isOnline.val()) {
// If we lose our internet connection, we want ourselves removed from the list.
myUserRef.onDisconnect().remove();
}
});
};
ty.Presence.prototype.count = function(roomID, cb) {
var self = this
var userListRef = this.presence.child(roomID)
var count = 0
function res () {
var usersArr = _.pluck(users, 'id')
usersArr = _.uniq(usersArr)
count = usersArr.length
if (cb) cb(count)
}
var users = {}
userListRef.on("child_added", function(css) {
users[css.name()] = css.val();
res()
});
userListRef.on("child_removed", function(css) {
delete users[css.name()]
res()
});
cb(count)
};
ty.Presence.prototype.get = function(ref) {
return this[ref]
};
ty.Presence.prototype.setGlobal = function(object) {
var self = this
_.each(this.rooms, function (myUserRef) {
myUserRef.set(object)
})
};
ty.Presence.prototype.remove = function(roomID) {
if (this.rooms[roomID])
this.rooms[roomID].remove();
};
ty.Presence.prototype.off = function(roomID) {
var userListRef = this.presence.child(roomID)
userListRef.off()
};
ty.presence = new ty.Presence()
ty.presence.add('all')
The onDisconnect handlers can be lost if a Firebase is restarted (e.g. when a new release is pushed live). One simple approach is to attach a timestamp as a priority to the records when they are stored. As long as the client remains online, have him update the timestamp occasionally.
setInterval(function() {
connectedRef.setPriority(Date.now());
}, 1000*60*60*4 /* every 4 hours */ );
Thus, any record which reaches, say, 24 hours old, would obviously be an orphan. A challenge could take place by clients (e.g. when a new client receives the list for the first time) or by a server process (e.g. a node.js script with a setInterval() to check for records older than X).
presenceRef.endAt(Date.now()-24*60*60*1000 /* 24 hours ago */).remove();
Less than ideal, sure, but a functional workaround I've utilized in apps.