Cannot read property 'Router' of undefined in expressJS?

Question

I am creating a backend app using Express JS. But while testing the code on live server, I am getting error: Cannot read property 'Router' of undefined. Here is my code:

Server.js

var Todo = require('./models/Todo');
var router = express.Router();
var express = require('express'),
      path = require('path'),
      bodyParser = require('body-parser'),
      cors = require('cors'),
      mongoose = require('mongoose');

router.route('/create').post((req, res) => {
  var todo = new Todo(req.body);
   todo.save().then( todo => {
   res.status(200).json({'message': 'Todo successfully added '});
   })
   .catch(err => {
    res.status(400).send("Error when saving to database");
   });
});

router.route('/todos').get((req, res) => {
  Todo.find((err, todos) =>{
    if(err){
      console.log(err);
    }
    else {
      res.json(todos);
    }
  });
});
router.route('/todos/:id').get((req, res) => {
  var id = req.params.id;
  Todo.findById(id, (err, todo) =>{
      res.json(todo);
  });
});

router.route('/todos/:id').put((req, res) => {
  Todo.findById(req.params.id, (err, todo) => {
    if (!todo)
      return next(new Error('Error getting the todo!'));
    else {
      todo.name = req.body.name;
      todo.save().then( todo => {
          res.json('Todo updated successfully');
      })
      .catch(err => {
            res.status(400).send("Error when updating the todo");
      });
    }
  });
});

router.route('/todos/:id').get((req, res) => {
  Todo.findByIdAndRemove({_id: req.params.id}, (err,todo) =>{
        if(err) res.json(err);
        else res.json('Todo successfully removed');
    });
});



mongoose.connect("mongodb://localhost:27017/vuenodedb").then(
          () => {console.log('Database connection is successful') },
          err => { console.log('Error when connecting to the database'+ err)}
);
.........

I am referring this link for the tutorial purpose: https://www.techiediaries.com/vue-js-express-tutorial/

Answer 1

You are trying to access express before initializing it. Here is your code:

var router = express.Router();
var express = require('express');

Initialize express first then use Router .