问当没有语法错误时，邮递员坏请求错误

EN

const express = require('express');
const app = express();
const bodyParser = require('body-parser');
const cors = require('cors');
const mongoose = require('mongoose');
const articleRoutes = express.Router();
const PORT = 4000;

let Article = require('./article.model');

app.use(cors());
app.use(bodyParser.json());

mongoose.connect('mongodb://127.0.0.1:27017/articles', { useNewUrlParser: true, useUnifiedTopology: true });
const connection = mongoose.connection;

connection.once('open', function() {
    console.log("MongoDB database connection established successfully");
});

articleRoutes.route("/content-management-system/add").post((req, res) => {
    let article = new Article(req.body);
    console.log(article);
    article.save()
        .then(article => {
            res.status(200).json({'article': 'article saved successfully'});
        })
        .catch(err => {
            res.status(400).send('adding new article failed');
        });
});

app.use('/', articleRoutes);

app.listen(PORT, function() {
    console.log("Server is running on Port: " + PORT);
});