Node.js express-generator - 由于类型错误，应用程序无法运行：app.set 不是函数

Question

While setting up my app using nodejs and express-generator, I ran

npm install multer --save
npm audit fix

at my terminal. Then when I tried to run

node ./bin/www

in my terminal it showed me this error:

app.set('port', port);

^

TypeError: app.set is not a function

I haven't used multer yet.

As suggested in this , I've required express and used "module.exports = app" at the end of my app.js and it worked before I ran the commands above, so I really can't figure out what's wrong with my code.

myapp/bin/www

#!/usr/bin/env node

/**
 * Module dependencies.
 */

var app = require('../app');
var debug = require('debug')('myapp:server');
var http = require('http');

/**
 * Get port from environment and store in Express.
 */

var port = normalizePort(process.env.PORT || '3000');
app.set('port', port);

/**
 * Create HTTP server.
 */

var server = http.createServer(app);

/**
 * Listen on provided port, on all network interfaces.
 */

server.listen(port);
server.on('error', onError);
server.on('listening', onListening);

/**
 * Normalize a port into a number, string, or false.
 */

function normalizePort(val) {
  var port = parseInt(val, 10);

  if (isNaN(port)) {
    // named pipe
    return val;
  }

  if (port >= 0) {
    // port number
    return port;
  }

  return false;
}

/**
 * Event listener for HTTP server "error" event.
 */

function onError(error) {
  if (error.syscall !== 'listen') {
    throw error;
  }

  var bind = typeof port === 'string'
    ? 'Pipe ' + port
    : 'Port ' + port;

  // handle specific listen errors with friendly messages
  switch (error.code) {
    case 'EACCES':
      console.error(bind + ' requires elevated privileges');
      process.exit(1);
      break;
    case 'EADDRINUSE':
      console.error(bind + ' is already in use');
      process.exit(1);
      break;
    default:
      throw error;
  }
}

/**
 * Event listener for HTTP server "listening" event.
 */

function onListening() {
  var addr = server.address();
  var bind = typeof addr === 'string'
    ? 'pipe ' + addr
    : 'port ' + addr.port;
  debug('Listening on ' + bind);
}

app.js

var createError = require('http-errors');
var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var logger = require('morgan');

var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');
var productsRouter = require('./routes/products');
var adminRouter = require('./routes/admin');

var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'pug');

app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(bodyParser.urlencoded({ extended: true }));
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', indexRouter);
app.use('/users', usersRouter);
app.use('/products', productsRouter);
app.use('/admin', adminRouter);

// DataBase 
var mysql = require('mysql');

var db = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: '',
    database: 'stylish'
});

db.connect(function(err) {
    if (err) {
        console.log('MySQL connection error: '+err.message);
        return;
    }
    console.log('Connected to the MySQL server');
});

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  next(createError(404));
});

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});


module.exports = app;
module.exports = db;

Answer 1

In aap.js you are doing exports twice, so www file you will receive as an object

you need to use like this

var app = require('../app');
app=app.app

or

var app = require('../app').app; //recommended 

    or

app.app.set('port',port)