错误连接 MongoDB：错误：Route.get() 需要一个回调函数，但得到一个 [object Undefined]

Question

I have been trying to connect my application to MongoDB using express but without success. Below the most important part of the code:

app.js :

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

var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');

var mongoose = require('mongoose');
const bodyParser = require('body-parser');
const vesselController = require('./controllers/VesselController');
require('./config/keys');

var app = express();
app.use(cors());
app.options('*', cors());

// DB Config
const db = require('./config/keys').MongoURI;

const options = {
    useNewUrlParser: true,
    reconnectTries: Number.MAX_VALUE,
    poolSize: 10
};

mongoose
    .connect(db, options)
    .then(() => console.log('MongoDB Connection established'))
    .catch((err) => console.log('Error connecting MongoDB database due to: ', err));

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

// Bodyparser
app.use(express.urlencoded({ extended: false }));

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

app.use('/', indexRouter);
app.use('/users', usersRouter);

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

app.use((req, res, next) => {
    res.header('Access-Control-Allow-Origin', '*');
    next();
});

// 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');
});

const PORT = process.env.PORT || 3000;

app.use(bodyParser.urlencoded({ extended: true, limit: '50mb' }));
app.use(bodyParser.json({ limit: '50mb' }));
app.use(cors());

app.route('/vessels/all').get(vesselController.getBaseAll);
app.route('vessels/:id/track').get(vesselController.getCurrent);
app.route('/vessels').get(vesselController.getHistory);

app.listen(PORT, console.log(`Server started on port ${PORT}`));

module.exports = app;

VesselController.js

const Vessels = require('../models/Vessels');
const Positions = require('../models/Positions');
const Compnanies = require('../models/Companies');

exports.getBaseAll = (req, res) => {
    Promise.all([
        Compnanies.find(),
        Vessels.find(),
        Positions.aggregate([
            {
                $sort: {
                    date: -1
                }
            },
            {
                $group: {
                    _id: '$callsign',
                    details: {
                        $push: '$$ROOT'
                    }
                }
            },
            {
                $replaceRoot: {
                    newRoot: {
                        $arrayElemAt: [ '$details', 0 ]
                    }
                }
            }
        ])
    ])
        .then(([ companies, vessels, positions ]) => {
            // apply vessels detail table as join:
            positions.forEach((pos) => {
                vessels.forEach((ves) => {
                    if (pos.callsign == ves.callsign) {
                        p._detail = ves;
                    }
                });
                companies.forEach((com) => {
                    if (p._detail.company == com.number) {
                        p._detail = com;
                    }
                });
            });
            res.status(200).json(positions);
        })
        .catch((err) => {
            return res.status(500).send(err);
        });
};

exports.getHistory = (req, res) => {
    var id = req.param.id;
    Positions.find(
        {
            callsign: id,
            date: {
                $gte: new Date(Date.now() - 1000 * 60 * 60 * 24)
            }
        },
        (err, task) => {
            if (err) {
                return res.status(500).send(err);
            }
            res.status(200).json(task);
        }
    );
};

exports.getCurrent = (req, res) => {
    var currentPos = Positions.find({
        date: {
            $gte: new Date(Date.now() - 1000 * 60 * 60)
        }
    });
    currentPos.exec((err, task) => {
        if (err) {
            return res.status(500).send(err);
        }
        res.status(200).json(task);
    });
};

I am not sure if the problem is due to the fact that I am trying to connect to a specific database. After hitting connect to my application as shown below and copy/paste the key:

mongodb+srv://<username>:<password>@vessel-tracker-cluster-x2lpw.mongodb.net/test?retryWrites=true&w=majority

Below is how my cluser is organized:

And after accessing the collections you can see how the database is structured:

What I have done to solve the problem:

Posts that I came across and analyzed to solve the problem were:

1) This was useful but I could not solve the problem.

2) I used this other source but problem still stays.

3) This one was also useful but my problem still stay and MongoDB is not properly connecting

Thanks for pointing in the right direction for solving this problem.

Answer 1

As I see from the stack trace there's an error in app.js:77:27:

app.route('/vessels/all').get(vesselController.getBaseAll);

Though I've executed your code and it worked fine I would like to propose you the following:

1) Try to substitute exports with module.exports in your VesselController.js;

2) Try to debug app.js and see what vesselController.getBaseAll / vesselController.getCurrent / vesselController.getHistory returns:

console.log(vesselController.getBaseAll); // should be [Function]