Route.post() requires a callback function but got a [object Undefined]? Why am I getting this error?

Question

I'm working on the backend of my react project and I seem to be having some trouble with the backend for the info. When I do npm start I get an error saying Route.post() requires a callback function but got a [object Undefined] and I'm confused as to why.

Here is my server.js file

const express = require("express");
const cors = require("cors");
const dbConfig = require("./app/config/db.config");

const app = express();

var corsOptions = {
  origin: "http://localhost:8081"
};

app.use(cors(corsOptions));

// parse requests of content-type - application/json
app.use(express.json());

// parse requests of content-type - application/x-www-form-urlencoded
app.use(express.urlencoded({ extended: true }));

const db = require("./app/models");
const Role = db.role;

db.mongoose
  .connect(`mongodb+srv://tami00:[email protected]/test?retryWrites=true&w=majority`, {
    useNewUrlParser: true,
    useUnifiedTopology: true
  })
  .then(() => {
    console.log("Successfully connect to MongoDB.");
    initial();
  })
  .catch(err => {
    console.error("Connection error", err);
    process.exit();
  });

// simple route
app.use('/favourite', require('.app/routes/favourite.routes'));

// routes
// require(".app/routes/favourite.routes")(app);
require("./app/routes/auth.routes")(app);
require("./app/routes/user.routes")(app);

// set port, listen for requests
const PORT = process.env.PORT || 8080;
app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}.`);
});

function initial() {
  Role.estimatedDocumentCount((err, count) => {
    if (!err && count === 0) {
      new Role({
        name: "user"
      }).save(err => {
        if (err) {
          console.log("error", err);
        }

        console.log("added 'user' to roles collection");
      });

      new Role({
        name: "creator"
      }).save(err => {
        if (err) {
          console.log("error", err);
        }

        console.log("added 'creator' to roles collection");
      });

      new Role({
        name: "watcher"
      }).save(err => {
        if (err) {
          console.log("error", err);
        }

        console.log("added 'watcher' to roles collection");
      });
    }
  });
}

and here is my favourite.routes.js file. I have no issue with the other 2 routes.

const express =  require('express');
const router = express.Router();
const{Favourite} = require("../models/favourite.model");
const {auth} = require("../middlewares/authJwt");

router.post("/favouriteNumber", auth, (req, res) => {
    Favourite.find({"movieId": req.body.movieId})
        .exec((err, favourite) => {
            if(err) return res.status(400).send(err)
            res.status(200).json({success: true, favouriteNumber: favourite.length})
        })
})

router.post("/favourited", auth, (req, res) => {
    Favourite.find({"movieId": req.body.movieId, "userFrom": req.body.userFrom})
        .exec((err, favourite) => {
            if(err) return res.status(400).send(err) 

            let result = false;
            if(favourite.length !== 0) {
                result = true
            }

            res.status(200).json({success: true, favourited: result});


        })
})

router.post("/addToFavourite", auth, (req, res) => {
    
    const favourite = new Favourite(req.body)

    favourite.save((err, doc) => {
        if(err) return res.json({success: false, err})
        return res.status(200).json({success: true, doc})
    })
})

router.post("/removeFavorite", auth, (req, res) => {
    
    Favourite.findOneAndDelete({movieId: req.body.movieId, userFrom: req.body.userFrom})
        .exec((err, doc) => {
            if(err) return res.json({success: false, err})
            return res.status(200).json({success: true, doc})
        })
})

module.exports = router;

This is the favourite models where I'm creating the mongoose schema

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

const favSchema = mongoose.Schema({
    userFrom: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'User'
    }, 
    movieId : {
        type: String
    }, 
    movieTitle : {
        type: String
    }, 
    movieImg : {
        type: String
    }
})

const Favourite = mongoose.model('Favourite', favSchema);

module.exports = {Favourite}

Heres the middlewares auth file

const jwt = require("jsonwebtoken");
const config = require("../config/auth.config.js");
const db = require("../models");
const User = db.user;
const Role = db.role;

verifyToken = (req, res, next) => {
  let token = req.headers["x-access-token"];

  if (!token) {
    return res.status(403).send({ message: "No token provided!" });
  }

  jwt.verify(token, config.secret, (err, decoded) => {
    if (err) {
      return res.status(401).send({ message: "Unauthorized!" });
    }
    req.userId = decoded.id;
    next();
  });
};

isAdmin = (req, res, next) => {
  User.findById(req.userId).exec((err, user) => {
    if (err) {
      res.status(500).send({ message: err });
      return;
    }

    Role.find(
      {
        _id: { $in: user.roles }
      },
      (err, roles) => {
        if (err) {
          res.status(500).send({ message: err });
          return;
        }

        for (let i = 0; i < roles.length; i++) {
          if (roles[i].name === "admin") {
            next();
            return;
          }
        }

        res.status(403).send({ message: "Require Admin Role!" });
        return;
      }
    );
  });
};

isModerator = (req, res, next) => {
  User.findById(req.userId).exec((err, user) => {
    if (err) {
      res.status(500).send({ message: err });
      return;
    }

    Role.find(
      {
        _id: { $in: user.roles }
      },
      (err, roles) => {
        if (err) {
          res.status(500).send({ message: err });
          return;
        }

        for (let i = 0; i < roles.length; i++) {
          if (roles[i].name === "moderator") {
            next();
            return;
          }
        }

        res.status(403).send({ message: "Require Moderator Role!" });
        return;
      }
    );
  });
};

const authJwt = {
  verifyToken,
  isAdmin,
  isModerator
};
module.exports = authJwt;

Answer 1

const {auth} = require("../middlewares/authJwt"); uses destructuring, but your exports from ../middlewares/authJwt don't have a field auth. auth therefore is undefined.