我正在尝试在我的基于Express 4的应用程序中实现文件上传。我按照本教程：https://codeforgeek.com/2014/11/file-uploads-using-node-js/
在那段代码中：
var express = require('express');
var multer = require('multer');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var routes = require('./routes/index');
var users = require('./routes/users');
var app = express();
app.use(multer({
dest: './uploads/',
rename: function (fieldname, filename) {
return filename + Date.now();
},
onFileUploadStart: function (file) {
console.log(file.originalname + ' is starting ...')
},
onFileUploadComplete: function (file) {
console.log(file.fieldname + ' uploaded to ' + file.path)
done = true;
}
}));
行app.use（multer（{
导致错误：
C:\Development\HERA\hera_node\node_modules\express\lib\application.js:206
throw new TypeError('app.use() requires middleware functions');
^
TypeError: app.use() requires middleware functions
at EventEmitter.use (C:\Development\HERA\hera_node\node_modules\express\lib\
application.js:206:11)
at Object.<anonymous> (C:\Development\HERA\hera_node\app.js:17:5)
at Module._compile (module.js:460:26)
at Object.Module._extensions..js (module.js:478:10)
at Module.load (module.js:355:32)
at Function.Module._load (module.js:310:12)
at Function.Module.runMain (module.js:501:10)
at startup (node.js:129:16)
at node.js:814:3
可能是什么原因？我是node＆express的新手。 requires middleware functions的解释并没有告诉我什么。
本教程使用的是旧版本的Multer（准确地说是v0.1.6），其中当前版本的Multer是1.0.1。在这些版本之间需要设置和使用Multer的方式发生了变化，这就是为什么教程代码不再适用于最新的Multer。
快速解决方法是安装旧版本：
$ npm install [email protected]
但是，在某些时候，您可能想要转移到最新版本的Multer。
//运行java-script文件并打开视图页面，然后上传文件并提交//
const express = require('express');
const fileUpload = require('express-fileupload');
const app = express();
let date = require('date-and-time');
// default options
app.use(fileUpload());
app.post('/upload', function(req, res) {
if (!req.files)
return res.status(400).send('No files were uploaded.');
// The name of the input field (i.e. "sampleFile") is used to retrieve the uploaded file
let sampleFile = req.files.sampleFile;
let now = new Date();
var now1 = date.format(now, 'YYYY_MM_DD_HH_mm_ss');
var desired = now1.replace(/[^\w\s]/gi, '')
var name = now1 + "_" + req.files.sampleFile.name;
// Use the mv() method to place the file somewhere on your server
sampleFile.mv("./../nodejs_image_upload_example/Images/" + name, function(err) {
if (err)
return res.status(500).send(err);
res.send('File uploaded!');
});
});
app.listen(2000, function(a) {
console.log("Listening to port 2000");
});<html>
<body>
<form ref='uploadForm' id='uploadForm' action='http://localhost:2000/upload' method='post' encType="multipart/form-data">
<input type="file" name="sampleFile" />
<input type='submit' value='Upload!' />
</form>
</body>
</html>`