Develop Reference

Firebase Cloud Functions Async

I am making a function for firebase cloud functions, I want a function to be called every time a new document is created in "posts". I want this function to perform the tasks that I put inside the "onCeatePost" function.
The problem I have is that I'm not sure if this is the correct way to structure such a function.
In several firebase examples I have seen that it is always called return _; or return null; at the end of a task, but I don't know how to structure the function so that all the tasks are carried out, could someone help me to restructure my function or tell me what is wrong please.
There are several if statements in the function, if the created publication does not comply with them, I would like it to skip them but continue with the other tasks that I put inside the function.
I don't know if it's too much to ask, but I'm new to this language and I haven't been able to find the answer I'm looking for. Thank you!
exports.onPostCreate = functions.firestore.document("/posts/{postId}").onCreate(async (snap) => {
const post = snap.data();
if (post) {
try {
const topic = post.topic;
const contentForFeed = post.contentForFeed;
const uid = post.uid;
const previous = post.prev;
await db.collection("users").doc(uid).update({"stats.posts": admin.firestore.FieldValue.increment(1)});
if (topic) {
await db.collection("topics").doc(topic.id).collection("user-authors").doc(uid).set({"date": snap.createTime});
}
if (contentForFeed == true) {
const userPath = db.collection("users").doc(uid);
await userPath.update({"stats.lastUpdate": snap.createTime});
}
if (previous) {
const previousId = previous.id;
const previousUid = previous.uid;
const refPrev = db.collection("posts").doc(previousId);
await db.runTransaction(async (t) => {
const doc = await t.get(refPrev);
const priority = doc.data().stats.date;
const newDate = new admin.firestore.Timestamp(priority.seconds + 120, priority.nanoseconds);
await db.collection("posts").doc(previousId).update({"newDate": newDate});
});
if (previousUid != uid) {
const path = db.collection("users").doc(uid).collection("user-posts");
const dataToSet = {"timestamp": snap.createTime, "uid": uid, "postId": onReplyToPostId};
await path(dataToSet);
}
}
} catch (err) {
functions.logger.log(err);
}
} else {
return null;
}
});

You'll find below the adapted code (untested) with 4 corrections.
Here are explanations for the two most important ones:
(Correction 2) In a transaction you need to use the transaction's update() method and not the "standard one"
(Correction 4) When all the asynchronous work is complete you need to return a value or a Promise. See this documntation page for more details.
exports.onPostCreate = functions.firestore
.document('/posts/{postId}')
.onCreate(async (snap) => {
const post = snap.data();
if (post) {
try {
const topic = post.topic;
const contentForFeed = post.contentForFeed;
const uid = post.uid;
const previous = post.prev;
await db
.collection('users')
.doc(uid)
.update({
'stats.posts': admin.firestore.FieldValue.increment(1),
});
if (topic) {
await db
.collection('topics')
.doc(topic.id)
.collection('user-authors')
.doc(uid)
.set({ date: snap.createTime });
}
if (contentForFeed == true) {
const userPath = db.collection('users').doc(uid);
await userPath.update({ 'stats.lastUpdate': snap.createTime });
}
let previousUid; // <= Correction 1
if (previous) {
const previousId = previous.id;
previousUid = previous.uid; // <= Correction 1
const refPrev = db.collection('posts').doc(previousId);
await db.runTransaction(async (t) => {
const doc = await t.get(refPrev);
const priority = doc.data().stats.date;
const newDate = new admin.firestore.Timestamp(
priority.seconds + 120,
priority.nanoseconds
);
t.update(refPrev, { newDate: newDate }); // <= Correction 2
});
if (previousUid != uid) {
const path = db
.collection('users')
.doc(uid)
.collection('user-posts');
const dataToSet = {
timestamp: snap.createTime,
uid: uid,
postId: onReplyToPostId,
};
await path.add(dataToSet); // <= Correction 3
}
}
return null; // <= Correction 4
} catch (err) {
functions.logger.log(err);
}
} else {
return null;
}
});

Close MONGODB connection after data insertion

I want to populate my database with some random data. I have used Faker.js for generating that data. I'm using MongoDB on my localhost and all the data is properly following all the validation rules from the schema. I'm having problem with the closing connection of my connection after insertion of data. I want to close the connection soon after the data is populated. I'm using async function to be aware of all the things but something is not going right.
Here is my code seeds.js which is the script im using to populate database
const path = require("path");
require("dotenv").config({ path: path.resolve(__dirname, "../.env") });
var mongoose = require("mongoose");
mongoose.connect(process.env.MONGODB_URI);
require("../models/User");
require("../models/Item");
require("../models/Comment");
var Item = mongoose.model("Item");
var Comment = mongoose.model("Comment");
var User = mongoose.model("User");
const ItemData = require("../data/item.json");
const CommentData = require("../data/comment.json");
const UserData = require("../data/user.json");
async function InsertData() {
ItemData.forEach(async (item) => {
item.seller = item.seller.$oid;
const oldItem = await Item.find({ title: item.title });
if (!oldItem.length) {
var newItem = new Item(item);
await newItem.save();
} else {
console.log(item.slug);
}
});
UserData.forEach(async (user) => {
const oldUser = await User.find({ username: user.username });
if (!oldUser.length) {
var user = new User(user);
await user.save();
} else {
console.log(user.username);
}
});
CommentData.forEach(async (comment) => {
comment.item = comment.item.$oid;
comment.seller = comment.seller.$oid;
var newComment = new Comment(comment);
const oldComment = await Comment.find({ _id: newComment.id });
if (!oldComment.length) {
await newComment.save();
} else {
console.log(comment.body);
}
});
}
async function cleanup() {
await Item.deleteMany({}, () => console.log("Data Cleared Item"));
await Comment.deleteMany({}, () => console.log("Data Cleared Comment"));
await User.deleteMany({}, () => console.log("Data Cleared User"));
}
async function main() {
InsertData().then(async () => {
console.debug('Data Inserted. Closing connection.');
await mongoose.connection.close();
});
}
main();
Here is the stack trace of the error
/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/core/connection/pool.js:841
cb(new MongoError('pool destroyed'));
^
MongoError: pool destroyed
at Pool.write (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/core/connection/pool.js:841:8)
at _command (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/core/wireprotocol/command.js:120:10)
at command (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/core/wireprotocol/command.js:28:5)
at Object.query (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/core/wireprotocol/query.js:66:3)
at Server.query (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/core/topologies/server.js:644:16)
at FindOperation.execute (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/operations/find.js:38:12)
at /Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/operations/execute_operation.js:144:17
at Server.selectServer (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/core/topologies/server.js:832:3)
at Server.selectServer (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/topologies/topology_base.js:342:32)
at executeWithServerSelection (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/operations/execute_operation.js:131:12)
at /Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/operations/execute_operation.js:70:9
at maybePromise (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/utils.js:685:3)
at executeOperation (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/operations/execute_operation.js:34:10)
at Cursor._initializeCursor (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/core/cursor.js:534:7)
at Cursor._initializeCursor (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/cursor.js:186:11)
at nextFunction (/Users/karnikkanojia/Desktop/Anythink-Market-21cto/backend/node_modules/mongodb/lib/core/cursor.js:737:10)
error Command failed with exit code 1.

Mongoose data Writing issue in Javascript

Just started with a javascript couple of days back. I am trying to use MongoDB with mongoose to write the data but it is not writing even though the connection is established.
I would really appreciate it if you can help me point out what I am missing here.
dbtest.js - module to create connection
require("dotenv").config();
const mongoose = require("mongoose");
const Block = require("./model/blockSchema");
const connectDB = async () => {
try {
await mongoose.connect(process.env.DATABASE_URI, {
useUnifiedTopology: true,
useNewUrlParser: true,
});
console.log("CONNECTED to MONGODB DATABASE");
} catch (err) {
console.error(err);
}
};
module.exports = connectDB;
blockchain.js
Even though I have verified the connection before calling the main method, it looks like the connection is not available to class methods.
require("dotenv").config();
const { hash256 } = require("../util/util");
const block = require("./block");
const blockchain = require("./blockHeader");
const Block = require("../database/model/blockSchema");
const { mongoose } = require("mongoose");
const connect = require("../database/dbtest");
VERSION = 1;
const ZERO_HASH = String("0").padStart(64, "0");
// Create connection
connect();
class Blockchain {
GenesisBlock() {
try {
const BlockHeight = 0;
const prevBlockHash = ZERO_HASH;
this.addBlock(BlockHeight, prevBlockHash);
} catch (err) {
console.log(`Error in Genesis Blockchain Function \n ${err}`);
}
}
addBlock(BlockHeight, prevBlockHash) {
let timestamp = Date.now();
let Transaction = `Codies Alert sent ${BlockHeight} to Anni`;
let merkleRoot = hash256(Transaction);
let bits = "ffff001f";
let blockHeader = new blockchain.BlockHeader(
VERSION,
prevBlockHash,
merkleRoot,
timestamp,
bits
);
//Mine a Block
blockHeader.mine();
// Create Schema Instance to Write the data
let BlockObj = new Block({
Height: BlockHeight,
BlockSize: 1,
blockHeader: {
version: 1,
prevBlockHash: "00000",
timestamp: timestamp,
bits: bits,
nonce: blockHeader.nonce,
blockHash: blockHeader.blockhash,
},
TxCount: 1,
Transactions: Transaction,
});
// Mongoose Schema, Write data
BlockObj.save((err) => {
if (err) return console.log(`Error while Writing the Block ${err}`);
console.log(`Block Written Successfully!!!!!!!`);
});
this.chain = new block.Block(BlockHeight, 1, blockHeader, 1, Transaction);
console.log(BlockObj);
}
// Main Function to trigger the process
main() {
this.chain = "";
this.GenesisBlock();
while (true) {
let lastBlock = this.chain;
let Blockheight = lastBlock.Height + 1;
let prevBlockHash = lastBlock.BlockHeader.blockhash;
this.addBlock(Blockheight, prevBlockHash);
}
}
}
mongoose.connection.once("open", async () => {
console.log("Connection Verified and ready to write data");
// Create an instance and call the main method
const blockchain = new Blockchain();
blockchain.main();
});
Issue was due to async/await. Here is the updated code that works.
require("dotenv").config();
const { hash256 } = require("../util/util");
const block = require("./block");
const blockchain = require("./blockHeader");
const Block = require("../database/model/blockSchema");
const connect = require("../database/dbtest");
const getLastBlock = require("../database/read");
VERSION = 1;
const ZERO_HASH = String("0").padStart(64, "0");
let mongoose = "";
class Blockchain {
async GenesisBlock() {
try {
console.log(mongoose.connection.readyState);
const BlockHeight = 0;
const prevBlockHash = ZERO_HASH;
await this.addBlock(BlockHeight, prevBlockHash);
} catch (err) {
console.log(`Error in Genesis Blockchain Function \n ${err}`);
}
}
async addBlock(BlockHeight, prevBlockHash) {
let timestamp = Date.now();
let Transaction = `Codies Alert sent ${BlockHeight} to Anni Maan`;
let merkleRoot = hash256(Transaction);
let bits = "ffff001f";
let blockHeader = new blockchain.BlockHeader(
VERSION,
prevBlockHash,
merkleRoot,
timestamp,
bits
);
blockHeader.mine();
let BlockObj = {
Height: BlockHeight,
BlockSize: 1,
blockHeader: {
version: 1,
prevBlockHash: blockHeader.prevBlockhash,
merkleroot: merkleRoot,
timestamp: timestamp,
bits: bits,
nonce: blockHeader.nonce,
blockhash: blockHeader.blockhash,
},
TxCount: 1,
Transactions: Transaction,
};
// Mongoose Schema, Write data
try {
await new Block(BlockObj).save();
console.log(BlockObj);
console.log("Block Written Successfully");
this.chain = new block.Block(BlockHeight, 1, blockHeader, 1, Transaction);
} catch (err) {
console.log(`Error in addBlock Function \n ${err}`);
}
}
// Main Function to trigger the process
async main() {
const lastBlock = await getLastBlock.main(true);
console.log(lastBlock[0]);
this.chain = lastBlock[0];
if (!this.chain) {
await this.GenesisBlock();
}
while (true) {
console.log(mongoose.connection.readyState);
let lastBlock = this.chain;
let Blockheight = lastBlock.Height + 1;
let prevBlockHash = lastBlock.blockHeader.blockhash;
await this.addBlock(Blockheight, prevBlockHash);
}
}
}
const createConnection = async () => {
try {
mongoose = await connect();
const blockchain = new Blockchain();
blockchain.main();
} catch (err) {
console.log("Error while con", err);
}
};
createConnection();

The issue in your code is due to the asynchronous programming, whenever you make a db call it is an asynchronous request and you will need to use async-await or Promises to make it work. In your previous code you haven't used async await thats why your data is not getting written into the db.
You can learn about async await here link and about promises here.
Please go through it, promises are the core concept of js and you will definitely need it if you are using node js.
Also try to learn about synchronous and asynchronous from here, these are really necessary and base of node js.
All these db calls needs to call with promises or async await to make it work.

why does my discord bot don't seem to hear?

Well, I would create a discord bot that will stock given data in a database, .then I began to learn js
Until now i haven't any problem and found a lot of help in the web, before to create the database i tried to show detected data on the console but now I'm blocked and can't understand by myself where is the problem.
here is my code
const Discord = require('discord.js')
const client = new Discord.Client();
const { promisify } = require('util')
const sleep = promisify(setTimeout)
require('dotenv').config();
const BOT_TOKEN = '******'
client.on('ready', async () => {
console.log(`The bot is now working !\n\n`);
});
client.on('message', async (receivedMessage) => {
// Prevent bot from responding to its own messages
if (receivedMessage.author == client.user) {
return;
}
const { author, content, channel } = receivedMessage;
const { id } = author;
const trimmedContent = content.trim();
if (trimmedContent.startsWith('!ins')) {
console.log('Inside ins');
module.exports = {
prefix: "!ins",
fn: (msg) => {
let application = {}
let filter = (msg) => !msg.author.bot;
let options = {
max: 1,
time: 15000
};
msg.member.send("nom ?")
.then(dm => {
// After each question, we'll setup a collector on the DM channel
return dm.channel.awaitMessages(filter, options)
})
.then(collected => {
// Convert the collection to an array & get the content from the first element
application.name = collected.array()[0].content;
// Ask the next question
return msg.member.send("Parfait, maintenant votre mail ?")
})
.then(dm => {
return dm.channel.awaitMessages(filter, options)
})
.then(collected => {
application.emailAddress = collected.array()[0].content;
return msg.member.send("Excellent. Enfin, quel est votre âge ?")
})
.then(dm => {
return dm.channel.awaitMessages(filter, options)
})
.then(collected => {
application.pitch = collected.array()[0].content;
console.log(application)
})
}
}
}
});
// client.login logs the bot in and sets it up for use. You'll enter your token here.
client.login(' ');
The problem is that bot doesn't react to !ins command and on the console I only have the console.log 2 and 3
if you need any more info, feel free to ask them and thanks for taken time

I do think that you should code your main structure like mine because yours is a bit messy.
const Discord = require('discord.js');
const client = new Discord.Client();
const BOT_TOKEN = '...';
client.on('ready', async () => {
console.log(`The bot is now working !\n\n`);
});
client.on('message', async (receivedMessage) => {
// Prevent bot from responding to its own messages
if (receivedMessage.author == client.user) {
return;
}
const { author, content, channel } = receivedMessage;
const { id } = author;
// Removes whitespace from both ends of a string, "I personally do like this"
const trimmedContent = content.trim();
if (trimmedContent.startsWith('!ins')) {
console.log('Inside ins');
}
});
client.login(BOT_TOKEN);
process.on('exit', () => {
client.destroy();
console.log(`The bot is now disconnected !\n\n`);
});

Transaction numbers are only allowed on storage engines that support document-level locking - MongodbMemoryServer/Mochai/Chai/Supertest

FIXED: USER storageEngine: "wiredTiger"
I use Mocha / Chai / Supertest and Mongodb-Memory-Server to test my app. But's I received error: Transaction numbers are only allowed on storage engines that support document-level locking
In real database and test by postman, it's working well.
My code:
In database.js
const mongoose = require('mongoose')
const { MongoMemoryReplSet } = require('mongodb-memory-server')
mongoose.set('useFindAndModify', false);
const connect = async () => {
try {
let url = process.env.MONGO_URL
let options = {
//Something
}
if (process.env.NODE_ENV === 'test') {
const replSet = new MongoMemoryReplSet();
await replSet.waitUntilRunning();
const uri = await replSet.getUri();
await mongoose.connect(uri, options)
//log connected
} else {
await mongoose.connect(url, options)
//log connected
}
} catch (error) {
//error
}
}
I have two model: Company and User. I made a function to add a member to company with used transaction. My code
const addMember = async (req, res, next) => {
const { companyId } = req.params
const { userId } = req.body
const session = await mongoose.startSession()
try {
await session.withTransaction(async () => {
const [company, user] = await Promise.all([
Company.findOneAndUpdate(
//Something
).session(session),
User.findByIdAndUpdate(
//Something
).session(session)
])
//Something if... else
return res.json({
message: `Add member successfully!`,
})
})
} catch (error) {
//error
}
}
Here's router:
router.post('/:companyId/add-member',
authentication.required,
company.addMember
)
Test file:
const expect = require('chai').expect
const request = require('supertest')
const app = require('../app')
describe('POST /company/:companyId/add-member', () => {
it('OK, add member', done => {
request(app).post(`/company/${companyIdEdited}/add-member`)
.set({ "x-access-token": signedUserTokenKey })
.send({userId: memberId})
.then(res => {
console.log(res.body)
expect(res.statusCode).to.equals(200)
done()
})
.catch((error) => done(error))
})
})
And i received error: Transaction numbers are only allowed on storage engines that support document-level locking'
How can I fix this?

Add retryWrites=false to your database uri. Example below:
mongodb://xx:xx#xyz.com:PORT,zz.com:33427/database-name?replicaSet=rs-xx&ssl=true&retryWrites=false