Mongoose.connect keeps coming back undefined

Question

I have this mongoose.connect statement in my server.js file:

const db = mongoose.connect(config.db, {
    'useNewUrlParser': true,
    'useUnifiedTopology': true,
    'useFindAndModify': false,
    'useCreateIndex': true
}, function(err, database) {
    if (err) {
        console.error(chalk.red('Could not connect to MongoDB!'));
        console.log(chalk.red(err));
    }else{
        console.log("db connected");
    }

});

// Init the express application
const app = require('./config/express')(db);

But when I reference the db constant in my express file, it keeps coming up as undefined.

What am I doing wrong here?

Answer 1

You should not pass it any callback. In that case mongoose would return you a Promise, which you'd need to await or .then(). E.g.

mongoose.connect(config.db, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
  useFindAndModify: false,
  useCreateIndex: true,
}).then((db) => {
  // Init the express application
  const app = require('./config/express')(db);
});