TypeError：模型不是构造函数

Question

使用Mongoose从Form Submit上的React组件上进行React组件进行MongoDB调用会引发错误-TypeError：组不是下面一行的构造函数

let group1 = new Group

我有一个服务器文件，在其中初始化连接。

server.js

const mongoose = require('mongoose');
mongoose.connect('dbName',{ useNewUrlParser: true });
mongoose.connection.once('open',() =>{
    console.log('connected to the database');
});

然后有一个名为group.js的模型文件

const mongoose = require('mongoose');

var groupSchema = new mongoose.Schema({
    groupName: String
});

module.exports = mongoose.model('Group',groupSchema);

组件CreateNew

const Group = require('../models/group');

class CreateNew extends Component {
// code here
render()
// code here

<Form onSubmit = {e => {

    let group1 = new Group({
    groupName: 'My Group'
    });
    group1.save(function(err,group1){
        if (err) return console.log(err);
        console.log('mongo success');
    });

}}>

当我把所有的代码在一个地方像这样的server.js文件中，然后代码工作，我可以在蒙戈看到的数据。

如果我只是将代码从Form的onSubmit内部移到“ Class NewNewextended Component”行之前，仅用于测试，那么它将引发以下错误

编译后无法覆盖Group模型。

在这条线

module.exports = mongoose.model('Group',groupSchema);

Answer 1

我将向您简要介绍该项目，其中包括前端和后端。

1. 后端

   1.1 server.js

    const express = require('express'); const app = express(); const port = process.env.PORT || 80; const http = require('http').Server(app); const mongoose = require('mongoose'); const routes = require(path_to_api.js)(router); app.use('/myApi', routes) //***Here you should implement more details about your project such as routes, body parsers and other middlewares*****// mongoose.connect('mongodb://localhost:27017/your-app-name', err => err?console.log(err):console.log('Successfully connected to MongoDB')); http.listen(port, ()=> console.log(`Server running on ${port}`)) 

   1.2模型，group.js

    const mongoose = require('mongoose'); const Schema = mongoose.Schema; let groupSchema = new Schema({ groupName: { type: String } }); module.exports = mongoose.model('Group',groupSchema); 

   1.3 api.js（仍然是后端!!!）

    const Group = require(path_to_group.js); module.exports = router => { router.post('/group', (req, res)=> { let group = new Group(); group.groupName = req.body.groupName; //Save in database group.save(function(err){ ... }) } return router } 

2. 前端

   2.1 Ajax调用（service.js）

    function group(data){ return fetch('/api/authenticate',{ method: 'POST', headers: { 'Accept': 'application/json', 'Content-type': 'application/json' }, body: JSON.stringify(data) }).then(response => response.json()).then(data => { return data //Server response }) } export {group} 

   2.2 React组件

    import {group} from //service.js path class CreateNew extends Component { constructor(props, context){ this.sendGroupName = this.sendGroupName.bind(this); } this.sendGroupName(){ let data = //data received from form after submit //It is the most important part from the frontend - sending data to the server group(data).then(res => { //do somenthing with servers response } } render(){ <Form onSubmit={this.sendGroupName}> //Form content such as inputs, labels... <Form/> } 

那是我对MEAN项目的快速解释。 我希望对您有用。