Error: Route.get() requires a callback function but got a [object Undefined] despite module.exports = router; being there?

Question

我正在尝试结合我的 CRUD 和 TODO 应用程序。但是，即使我已将 "module.exports = router;" 添加到我的路由 js 文件、server.js 文件和控制器 js 文件中，我仍收到此错误。我将在下面添加这些文件和我的文件夹文件结构。我错过了什么吗？

folder/file structure

server.js 文件

require('./models/db');
require('./models/task');

const express = require('express');
const path = require('path');
const exphbs = require('express-handlebars');
const bodyparser = require('body-parser');
const logger = require('morgan');
const mongoose = require('mongoose');
const favicon = require('serve-favicon');

const employeeController = require('./controllers/employeeController');

var app = express();

//setting up morgan middleware
app.use(logger('dev'));

app.use(bodyparser.urlencoded({
    extended: true
}));
app.use(bodyparser.json());

app.set('views', path.join(__dirname, '/views/'));
app.engine('hbs', exphbs({ extname: 'hbs', defaultLayout: 'mainLayout', layoutsDir: __dirname + '/views/layouts/' }));
app.set('view engine', 'hbs');

//serving blank favicon to keep from throwing 404 errors
app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')))

//setting up static path for serving static files
app.use(express.static(path.join(__dirname, 'public')));

//Bringing in the routes
const index = require('./routes/index');
const api = require('./routes/api');

app.use('/', index);
app.use('/api', api);


app.listen(3000, () => {
    console.log('Express server started at port : 3000');
});

app.use('/employee', employeeController);

module.exports = router;

employeeController.js 文件

const express = require('express');
var router = express.Router();
const mongoose = require('mongoose');
const Employee = mongoose.model('Employee');
const Task = require('../models/task');

router.get('/', (req, res) => {
    res.render("employee/addOrEdit", {
        viewTitle: "Insert Module"
    });
});

router.get('/test', (req, res) => {
    res.render("employee/test");
});


router.get('/edit', (req, res) => {
    res.render("edit");
});

router.get('/index', function(req, res) {
    res.render('employee/index', {layout: 'main.hbs'});
});

router.get('/edit', function(req, res) {
    res.render('employee/edit', {layout: 'main.hbs'});
});

router.post('/', (req, res) => {
    if (req.body._id == '')
        insertRecord(req, res);
        else
        updateRecord(req, res);
});


function insertRecord(req, res) {
    var employee = new Employee();
    employee.fullName = req.body.fullName;
    employee.module = req.body.module;
    employee.mobile = req.body.mobile;
    employee.city = req.body.city;
    employee.save((err, doc) => {
        if (!err)
            res.redirect('employee/list');
        else {
            if (err.name == 'ValidationError') {
                handleValidationError(err, req.body);
                res.render("employee/addOrEdit", {
                    viewTitle: "Insert Module",
                    employee: req.body
                });
            }
            else
                console.log('Error during record insertion : ' + err);
        }
    });
}

function updateRecord(req, res) {
    Employee.findOneAndUpdate({ _id: req.body._id }, req.body, { new: true }, (err, doc) => {
        if (!err) { res.redirect('employee/list'); }
        else {
            if (err.name == 'ValidationError') {
                handleValidationError(err, req.body);
                res.render("employee/addOrEdit", {
                    viewTitle: 'Update Module',
                    employee: req.body
                });
            }
            else
                console.log('Error during record update : ' + err);
        }
    });
}


router.get('/list', (req, res) => {
    Employee.find((err, docs) => {
        if (!err) {
            res.render("employee/list", {
                list: docs
            });
        }
        else {
            console.log('Error in retrieving module list :' + err);
        }
    });
});


function handleValidationError(err, body) {
    for (field in err.errors) {
        switch (err.errors[field].path) {
            case 'fullName':
                body['fullNameError'] = err.errors[field].message;
                break;
            case 'module':
                body['moduleError'] = err.errors[field].message;
                break;
            default:
                break;
        }
    }
}

router.get('/:id', (req, res) => {
    Employee.findById(req.params.id, (err, doc) => {
        if (!err) {
            res.render("employee/addOrEdit", {
                viewTitle: "Update Module",
                employee: doc
            });
        }
    });
});

router.get('/delete/:id', (req, res) => {
    Employee.findByIdAndRemove(req.params.id, (err, doc) => {
        if (!err) {
            res.redirect('/employee/list');
        }
        else { console.log('Error in module delete :' + err); }
    });
});

const sortTask = (a,b) => {
    const taskA = a.task.toLowerCase();
    const taskB = b.task.toLowerCase();
    return (taskA < taskB) ? -1 : (taskA > taskB) ? 1 : 0;
  }

  module.exports = {
    findAll: function (req,res){
      Task
      .find({})
      .then(result => {
        result.sort(sortTask)
        res.render('employee/index', {layout: 'main.hbs'}, {tasks: result})
      })
      .catch(err => res.json(err))
    },

    create: function(req,res){
      Task
      .create(req.body)
      .then(result => {
        // result.sort(sortTask)
        res.json(result)
      })
      .catch(err => res.json(err));
    },

    findOne: function (req,res){
      Task
      .findOne({_id: req.params.id})
      .then(result => res.render('employee/edit', {layout: 'main.hbs'}, result))
      .catch(err => res.json(err))
    },

    complete: function (req,res){
      Task
      .findOneAndUpdate({_id: req.params.id}, {completed: true})
      .then(result => res.json(result))
      .catch(err => res.json(err))
    },

    deleteOne: function (req,res){
      Task
      .remove({_id: req.params.id})
      .then(result => res.json(result))
      .catch(err => res.json(err))
    },

    updateName: function (req,res){
      Task
      .findOneAndUpdate({_id: req.body._id}, {task: req.body.task})
      .then(result => res.json(result))
      .catch(err => res.json(err))
    }
  }

  module.exports = router;

api.js 文件

const router = require('express').Router();
const taskController = require('../controllers/employeeController');

router
.route('/task/:id')
.get(taskController.findOne)
.put(taskController.complete)
.delete(taskController.deleteOne)

router.post('/create', taskController.create);

router.post('/update', taskController.updateName);

module.exports = router;

index.js 文件

const router = require('express').Router();
const taskController = require('../controllers/employeeController');

router.get('/', taskController.findAll)

module.exports = router;

Answer 1

您在 employeeController.js 中多次使用 module.exports = {...} 而这不是它的工作原理，请参阅 docs 以了解更多信息

要解决这个问题，只需将路由器添加到第一个导出的对象中，如下所示：

module.exports = {
  findAll: function (req,res) {
    ...
  },
  // rest of the functions
  updateName: function(req,res) {
   ...
  },
  router
}

 ̶m̶o̶d̶u̶l̶e̶.̶e̶x̶p̶o̶r̶t̶s̶ ̶=̶ ̶r̶o̶u̶t̶e̶r̶;̶

然后在server.js中使用这样的路由器：

app.use('/employee', employeeController.router);

Error: Route.get() requires a callback function but got a [object Undefined] despite module.exports = router; being there?

Error: Route.get() requires a callback function but got a [object Undefined] despite module.exports = router; being there?

node.js

express

handlebars.js

node-modules

express-handlebars