尝试将文章添加到文档时出现什么问题

Question

我想用react项目创建一个Crud应用程序。我按照课程https://appdividend.com/2018/11/11/react-crud-example-mern-stack-tutorial/进行操作。当我向文档中添加新文章时，导致控制台“无法保存到数据库”

这是我在前端的代码

import { Form, Icon, Input, Button } from 'antd';
import React from 'react';
import 'antd/dist/antd.css';
import 'containers/Layout/index.style.js';
import axios from 'axios';

class Index extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      link: "",
      title: "",
    }

    this.onChangeLink = this.onChangeLink.bind(this);
    this.onChangeTitle = this.onChangeTitle.bind(this);
    this.onSubmit = this.onSubmit.bind(this);
  }
  onChangeLink(e) {
    this.setState({
      link: e.target.value
    });
  }
  onChangeTitle(e) {
    this.setState({
      title: e.target.value
    })
  }

  onSubmit(e) {
    e.preventDefault();
    const obj = {
      link: this.state.link,
      title: this.state.title,
    };
    axios.post('http://localhost:3030/api/add', obj)
      .then(res => console.log(res.data));

    this.setState({
      link: "",
      title: "",
    })
  }
  render() {
    return (
      <Form onSubmit={this.onSubmit}>
        <Form.Item label="Title">
          <Input placeholder="" onChange={this.onChangeTitle} />
        </Form.Item>
        <Form.Item label="Link">
          <Input placeholder="" onChange={this.onChangeLink} />
        </Form.Item>
        <input type="submit" value="Submit" />
      </Form>
    );
  }
}

export default Index;

这是我在后端的代码

router.route('/add').post(function (req, res) {
    let business = new Article(req.body);
    business.save()
      .then(business => {
        res.json({'business': 'business in added successfully'});
      })
      .catch(err => {
      res.send("unable to save to database");
      });
  });

我的代码错误吗？