从前端表单发出发布请求时出现内部服务器错误500

Question

我通过在前端填写表格来发出发布请求时，收到内部服务器错误500的信息，请有人帮忙。另外，当我向邮递员发出请求时，也会发生相同的错误。该如何解决？

学生模型后端代码和前端代码

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

const studentSchema = new Schema({
    studentName: {
        type: String, 
        required: true 
    },
    sid: {
        type: String, 
        unique: true, 
        required: true
    },
    mobileNo: {
        type: String, 
        unique: true, 
        required: true 
    },
    gender: {
        type: String,
        required: true
    },
    email: {
        type: String, 
        required: true 
    },
    branch: {
        type: String,
        required: true
    },
    nationality: {
        type: String,
        required: true,
    },
    address:{
        type: String,
        required: true,
    },
    fatherName: {
        type: String, 
        required: true 
    },
    motherName: {
        type: String, 
        required: true 
    },
    fatherMobile: {
        type: String,  
        required: true 
    },
    dob: {
        type: String,
        required: true
    },
    photo: {
        type: String,
        required: true
    },
    roomNo: {
        type: String,
        required: true
    },
    hostel: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Hostel'
    },
});

const Students = mongoose.model("Student", studentSchema);

module.exports = Students

后端代码

studentRouter.route('/')
.options(cors.corsWithOptions, (req, res) => { res.sendStatus(200); })
.get(cors.cors, authenticate.verifyUser, (req, res, next) => {
    console.log(req.user.hostel)
    Students.find({hostel: req.user.hostel})
    .populate('hostel')
    .then((students) => {
        res.statusCode = 200;
        res.setHeader('Content-Type', 'application/json')
        res.json(students);
    }, err => next(err))
    .catch(err => next(err))
})

.put(cors.corsWithOptions, authenticate.verifyUser, authenticate.verifyAdmin, (req, res, next) => {
    res.end('Put request not valid on the /students end point')
})

.post(cors.corsWithOptions, authenticate.verifyUser, authenticate.verifyAdmin, (req, res, next) => {
    req.body.hostel = req.user.hostel;
    Students.create(req.body)
    .then((student) => {
        Students.findById(student._id)
        .populate('hostel')
        .then((student) => {
            res.statusCode = 200;
            res.setHeader('Content-Type', 'application/json');
            res.json(student)
        }, err => next(err))
    }, (err) => next(err))
    .catch((err) => next(err))
})

前端代码

export const postStudent = (student) => (dispatch) => {

    const newStudent = {
        studentName: student.name,
        sid: student.id,
        mobileNo: student.mobile,
        gender: student.gender,
        email: student.email,
        branch: student.branch,
        nationality: student.nationality,
        address: student.address,
        fatherName: student.father,
        motherName: student.mother,
        fatherMobile: student.Fnum,
        dob: student.dob,
        photo: student.photo
    }
    console.log('Student: ', newStudent);

    const bearer = 'Bearer ' + localStorage.getItem('token');

    return fetch(baseUrl + 'students', {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
            'Authorization': bearer
        },
        body: JSON.stringify(newStudent),
        credentials: "same-origin"
    })
    .then(response => {
        console.log(response);
        if (response.ok) {
            return response;
        }
        else {
            var error = new Error('Error ' + response.status + ': ' + response.statusText);
            error.response = response;
            throw error;
        }
    },
    error => {
        var errmess = new Error(error.message);
        throw errmess;
    })
    .then(response => response.json())
    .then(response => dispatch(addStudent(response)))
    .catch(error => { console.log('Post students ', error.message);
        alert('Your student could not be added\nError: '+ error.message); })
}