As @Laurent Perrin’s answer: If you don’t do it, you risk triggering the callback a second time later, which usually has devastating results I give an example here if you write middleware like this: app.use((req, res, next) => { console.log(‘This is a middleware’) next() console.log(‘This is first-half middleware’) }) app.use((req, res, next) => { console.log(‘This … Read more
You can nest routers by attaching them as middleware on an other router, with or without params. You must pass {mergeParams: true} to the child router if you want to access the params from the parent router. mergeParams was introduced in Express 4.5.0 (Jul 5 2014) In this example the itemRouter gets attached to the … Read more
In Express 3.0, you normally would use app.configure() (or app.use()) to set up the required middleware you need. Those middleware you specified are bundled together with Express 3.0. Example: var express = require(‘express’); var routes = require(‘./routes’); var user = require(‘./routes/user’); var http = require(‘http’); var path = require(‘path’); var app = express(); // all … Read more
Another reason you might get this error is if you use the same model in different files but your require path has a different case. For example, in my situation I had require(‘./models/User’) in one file, and then in another file where I needed access to the User model, I had require(‘./models/user’). I guess the … Read more
You can create a mongoUtil.js module that has functions to both connect to mongo and return a mongo db instance: const MongoClient = require( ‘mongodb’ ).MongoClient; const url = “mongodb://localhost:27017”; var _db; module.exports = { connectToServer: function( callback ) { MongoClient.connect( url, { useNewUrlParser: true }, function( err, client ) { _db = client.db(‘test_db’); return … Read more
I believe it’s because of the relative path; the “../” is considered malicious. Resolve the local path first, then call res.sendfile. You can resolve the path with path.resolve beforehand. var path = require(‘path’); res.sendFile(path.resolve(‘temp/index.html’));
I guess you did not have the make tools available when you installed your mongodb library. I suggest you do xcode-select –install (on a mac) or sudo apt-get install gcc make build-essential (on ubuntu) and run rm -rf node_modules npm cache clean npm install OR just npm update based on @tobias comment (after installing build-essential) … Read more
You have to explicitly set extended for bodyParser.urlencoded() since the default value is going to change in the next major version of body-parser. Example: app.use(bodyParser.urlencoded({ extended: true })); Since express 4.16.0, you can also do: app.use(express.urlencoded({ extended: true }))
I think, npm init will create your missing package.json file. It works for me for the same case.
You had run another server use the same port like 8080. Maybe you had run node app in other shell, Please close it and run again. You can check PORT no. is available or not using netstat -tulnp | grep <port no> Alternatively, you can use lsof: lsof -i :<port no>