NodeJS连接MongoDB Atlas遇ReferenceError: string未定义问题求助

1. Resolve the ReferenceError in userModel.js #

The error occurs because Mongoose schema types require capitalized constructor names (e.g., String, not lowercase string). Here's the corrected file:

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

const userSchema = new Schema({
    email: {
        type: String, // Corrected from string to String
        required: true
    },
    password: {
        type: String, // Corrected from string to String
        required: true
    },
    confirmpassword: {
        type: String, // Corrected from string to String
        required: true
    }
}, { timestamps: true })

const User = mongoose.model('User', userSchema);
module.exports = User;

Note: Your signup form doesn’t include a confirmpassword field—either add it to the form or remove this field from the schema to avoid validation failures.

2. Correct Form Action in signup.ejs #

The form’s action attribute points to the wrong path. Since your server maps /signup to signupRoutes.js, update the action to /signup:

<form action="/signup" method="post">
     <label for="email">Email:</label>
     <input type="email" id="email" name="email" required><br><br>
     <label for="password">Password:</label>
     <input type="password" id="password" name="password" required><br><br>
     <!-- Uncomment below if you keep confirmpassword in the schema -->
     <!-- <label for="confirmpassword">Confirm Password:</label>
     <input type="password" id="confirmpassword" name="confirmpassword" required><br><br> -->
     <input type="submit" value="Submit">
</form>

Also updated password input type to password for security and added required attributes for basic client-side validation.

3. Fix Route Logic in signupRoutes.js #

• Use router.post instead of app.post (you’re working with a router instance, not the main app)
• Add async/await handling for user.save() to avoid unhandled promise rejections
• Align the route path with how the router is mounted (use / instead of /signup)

Corrected file:

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

const User = require('../models/userModel');

router.get('/', (req, res) => {
    res.render('./signup');
    // Remove res.end()—res.render already sends the response
});

router.post('/', async (req, res) => {
    try {
        const user = new User({
            email: req.body.email,
            password: req.body.password,
            confirmpassword: req.body.confirmpassword // Include this if you added the field to the form
        }); 
        await user.save();
        res.redirect('/index'); // Redirect to your homepage route
    } catch (err) {
        console.error(err);
        res.status(400).send('Failed to create user');
    }
});

module.exports = router;

4. Add Body Parsing Middleware in server.js #

Without this middleware, req.body will be undefined when handling POST requests. Add this line before your route declarations:

const express = require('express');
const app = express();
const mongoose = require('mongoose');
const ejs = require('ejs');

const homepageRoutes = require('./routes/homepageRoutes');
const signupRoutes = require('./routes/signupRoutes');
const loginRoutes = require('./routes/loginRoutes');

const dotenv = require('dotenv');
dotenv.config();
const dbusername= process.env.DB_USERNAME;
const dbpassword= process.env.DB_PASSWORD;
const dbURI = `mongodb+srv://${dbusername}:${dbpassword}@testingcluster.ix9mpsg.mongodb.net/?retryWrites=true&w=majority`; // Added const to avoid global scope leak

mongoose.connect(dbURI).then((result) => app.listen(4000)).catch((err) => console.log(err));

app.set('view engine', 'ejs');
app.use(express.static('assets'));
app.use(express.urlencoded({ extended: true })); // Add this line to parse form data

app.use("/index", homepageRoutes);
app.use("/signup", signupRoutes);
app.use("/login", loginRoutes);

内容的提问来源于stack exchange，提问作者mughil singh