javascript - 使用node js和react js的文件加载问题

Question

我使用 Node.js 创建了一个 Web 服务。使用此服务，我想从 React 用户界面中选择用户信息和照片并将它们保存到 mongodb。但是照片的名称保存在 Mongodb 中，但照片没有保存在目录 ./public/uploads/. 下，我应该如何解决此错误？ Node js 和 React 刚刚开始学习。 我与您分享我在下面编写的代码。

型号

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

newSchema = new Schema({
    name : String,
    email : String,
    password : String,
    img: String
})

module.exports = mongoose.model('User', newSchema)

路线

const express = require('express')
const User = require('../models/index')
const router = express.Router()
const multer = require('multer')

var imgStorage = multer.diskStorage({
    destination: './public/uploads/',
    filename:(req, file, cb)=>{
        cb(null, file.fieldname+"_"+Date.now()+path.extname(file.originalname))
    }
})

var upload = multer({
    storage: imgStorage
}).single('file')


/* create new*/
router.post('/', upload, (req,res)=>{
    user = new User({
        name:req.body.name,
        email:req.body.email,
        password:req.body.password,
        img: req.body.img
    })

    user.save(()=>{
        res.json(user)
    })
})

/* find all users */
router.get('/', (req, res) => {
    User.find({},(err,data) =>{
        res.json(data)
    })
})

/* find user by id */
router.get('/:id',(req, res) =>{
    User.findById(req.params.id, (err, data) =>{
        res.json(data)
    })
})

/* delete user by id */
router.delete('/:id',async (req, res) =>{
    await User.findByIdAndDelete(req.params.id)
    res.json({'message':'deleted'})
})

/* update */
router.put('/:id', async (req, res)=>{
    await User.findByIdAndUpdate(req.params.is, req.body)
    res.json({'message':'updated'})
})

module.exports = router

索引

const express = require('express');
const mongoose = require('mongoose');
const mongodb = require('mongodb');
const cors = require('cors');
mongoose.connect('mongodb://localhost:27017/admin?authSource=$[authSource] --username $[username]', {useNewUrlParser : true});
const app = express();

app.use(express.json())
app.use(cors())
app.use(express.urlencoded({extended:true}))

app.use('/api',require('./routes/index'))

const port = process.env.PORT || 8080

app.listen(port)

module.exports =  new mongoose.model('User', newSchema)

react 方

import React, {Component} from 'react';
import axios from 'axios';

class App extends React.Component {

    constructor(props) {
        super(props);
        this.state = {
            users: [],
            id: 0,
            name: '',
            email: '',
            password: '',
            img: ''
        }
    }

    componentDidMount() {
        try {
            axios.get('http://localhost:8080/api')
                .then((res) => {
                    this.setState({
                        users: res.data,
                        id: 0,
                        name: '',
                        email: '',
                        password: '',
                        img: ''
                    })
                })
        } catch (e) {
            console.log(e)
        }
    }

    nameChange = event => {
        this.setState({
            name: event.target.value
        })
    }

    emailChange = event => {
        this.setState({
            email: event.target.value
        })
    }

    passwordChange = event => {
        this.setState({
            password: event.target.value
        })
    }

    fileSelectedHandler = event =>{
        this.setState({
            img : event.target.files[0]
        })
    }

    submit(event, id) {
        event.preventDefault()
        if (id === 0) {
            // const fd = new FormData();
            // fd.append('image', this.state.img, this.state.img.name);
            axios.post('http://localhost:8080/api', {
                name: this.state.name,
                email: this.state.email,
                password: this.state.password,
                //img: this.state.img
                img : this.state.img.name
            }).then(()=>{
                this.componentDidMount()
            })

        } else {
            axios.put('http://localhost:8080/api/'+id, {
                name: this.state.name,
                email: this.state.email,
                password: this.state.password,
                img: this.state.img
            }).then(()=>{
                this.componentDidMount()
            })
        }
    }

    deleteUser(id) {
        try {
            axios.delete('http://localhost:8080/api/' + id)
                .then((res) => {
                    this.componentDidMount()
                })
            console.log('Deleted successfully.')
        } catch (e) {
            console.log(e)
        }
    }

    editUser(id) {
        try {
            axios.get('http://localhost:8080/api/' + id)
                .then((res) => {
                    console.log(res.data)
                    this.setState({
                        id:res.data._id,
                        name: res.data.name,
                        email: res.data.email,
                        password: res.data.password
                    })
                })
        } catch (e) {
            console.log(e)
        }
    }

    render() {
        return (
            <div className="row">
                <div className="col s6">
                    <form onSubmit={(e) => this.submit(e, this.state.id)}>
                        <div className="input-field col s12">
                            <i className="material-icons prefix">person</i>
                            <input value={this.state.name} onChange={(e) => this.nameChange(e)} type="text" id="autocomplete-input"
                                   className="autocomplete" required/>
                            <label htmlFor="autocomplete-input">Name</label>
                        </div>
                        <div className="input-field col s12">
                            <i className="material-icons prefix">mail</i>
                            <input value={this.state.email} onChange={(e) => this.emailChange(e)} type="email" id="autocomplete-input"
                                   className="autocomplete" required/>
                            <label htmlFor="autocomplete-input">Email</label>
                        </div>
                        <div className="input-field col s12">
                            <i className="material-icons prefix">vpn_key</i>
                            <input value={this.state.password} onChange={(e) => this.passwordChange(e)} type="password" id="autocomplete-input"
                                   className="autocomplete" required/>
                            <label htmlFor="autocomplete-input">Password</label>
                        </div>
                        <div className="input-field col s12">
                            <input type="file" name="file" onChange={(e) => this.fileSelectedHandler(e)}/>
                        </div>
                        <br/>
                        <button className="btn waves-effect waves-light right blue" type="submit" name="action">Submit
                            <i className="material-icons right">send</i>
                        </button>
                    </form>
                </div>
                <div className="col s6">
                    <table>
                        <thead>
                        <tr>
                            <th>Name</th>
                            <th>Email</th>
                            <th>Password</th>
                            <th>IMG</th>
                            <th>Edit</th>
                            <th>Delete</th>
                        </tr>
                        </thead>
                        <tbody>
                        {this.state.users.map(user =>
                            <tr key={user._id}>
                                <td>{user.name}</td>
                                <td>{user.email}</td>
                                <td>{user.password}</td>
                                <td>
                                    <img src="./public/uploads/user.img.name" width="80"/>
                                </td>
                                <td>
                                    <button onClick={(e) => this.editUser(user._id)}
                                            className="btn waves-effect waves-light green" type="submit" name="action">
                                        <i className="material-icons right">edit</i>
                                    </button>
                                </td>
                                <td>
                                    <button onClick={(e) => this.deleteUser(user._id)}
                                            className="btn waves-effect waves-light red" type="submit" name="action">
                                        <i className="material-icons right">delete</i>
                                    </button>
                                </td>
                            </tr>
                        )}
                        </tbody>
                    </table>
                </div>
            </div>
        );
    }

}

export default App;

Answer 1

    You have to send file inside formData to the server like 
    inside submit function. Then send fd to server

          const formData = new FormData();
                formData.append('image', this.state.img);
     formData.append('name', this.state.name);
     formData.append('password', this.state.password);
     formData.append('password', this.state.email);

axios.post('/yourEndpoint', formData).then(res => {
  //Now do what you want with the response;
})