我使用node js，react js，mongodb创建了一个应用程序。我想使用multer上传文件，但是文件不上传。我与您共享了为前端和后端编写的代码块。如何使用multer将imgae成功注册到mongodb。我在互联网上进行了很多搜索，但我非常困惑。如果可以的话，我会很高兴。
模型
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
newSchema = new Schema({
name : String,
email : String,
password : String,
img:{
type: String
}
})
module.exports = mongoose.model('User', newSchema)
后端-路由/ index.js
const express = require('express')
const User = require('../models/index')
const router = express.Router()
//
const multer = require('multer')
const uuidv4 = require('uuid/v4')
const DIR = './public/';
const storage = multer.diskStorage({
destination: (req, file, cb) => {
cb(null, DIR);
},
filename: (req, file, cb) => {
const fileName = file.originalname.toLowerCase().split(' ').join('-');
cb(null, uuidv4() + '-' + fileName)
}
});
var upload = multer({
storage: storage,
fileFilter: (req, file, cb) => {
if (file.mimetype == "image/png" || file.mimetype == "image/jpg" || file.mimetype == "image/jpeg") {
cb(null, true);
} else {
cb(null, false);
return cb(new Error('Only .png, .jpg and .jpeg format allowed!'));
}
}
});
//
/* 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'})
})
/* create */
router.post('/',(req,res)=>{
const url = req.protocol + '://' + req.get('host')
const user = new User({
name:req.body.name,
email:req.body.email,
password:req.body.password,
img: url + '/public/' + req.file.filename
})
user.save(()=>{
res.json(user)
})
})
/* update */
router.put('/:id', async (req, res)=>{
await User.findByIdAndUpdate(req.params.is, req.body)
res.json({'message':'updated'})
})
module.exports = router
前端-反应端/App.js
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
})
}
submit(event, id) {
event.preventDefault()
if (id === 0) {
axios.post('http://localhost:8080/api', {
name: this.state.name,
email: this.state.email,
password: this.state.password,
img: this.state.img
}).then(()=>{
this.componentDidMount()
})
} else {
//axios.put('http://localhost:8080/api/'+id, {
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,
img: this.state.img
})
})
} 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>
<br/>
<button className="btn waves-effect waves-light right blue" type="submit" name="action">Submit
<i className="material-icons right">send</i>
</button>
<div>
<input type="file" id="myFile" name="filename"/>
</div>
</form>
</div>
<div className="col s6">
<table>
<thead>
<tr>
<th>Name Surname</th>
<th>Email</th>
<th>Password</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>
<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;
答案 0 :(得分：0)
将文件（已转换为字符串）上传到MongoDB并不是一个好习惯。我建议为此使用文件系统或服务，例如AWS S3。
之所以这样的做法不好，是因为诸如S3之类的服务可伸缩性更高，因为图像存储在多个服务器上，而诸如S3之类的服务则可以在content delivery network之后运行，该How to properly handle files upload using Node.js Express backend?会将图像的副本存储在世界各地的服务器。
要在文件系统上存储文件，请参见How do I save a file to MongoDB?。
如果文件很小，并且您希望将其内容存储在MongoDB上，请参见{{3}}。
答案 1 :(得分：0)
您应该在axios "Content-Type: "multipart/form-data"请求中传递标头-post。之后，您应该可以在Express路线的req.files中找到文件。
之后，您应该可以将文件上传到MongoDB。
尽管如此，您应该考虑使用AWS S3或Filestack之类的服务来存储文件，同时仅将URL存储在MongoDB中。
希望这会有所帮助！