我在c9上使用node.js中的multer和express，试图创建一个元数据读取器。我已经搜索了相当长的时间，但没有找到遇到此错误的任何人。错误是：
TypeError: fields.forEach is not a function
at Multer.setup (/home/ubuntu/workspace/node_modules/multer/index.js:29:12)
at multerMiddleware (/home/ubuntu/workspace/node_modules/multer/lib/make-middleware.js:20:19)
at Layer.handle [as handle_request] (/home/ubuntu/workspace/node_modules/express/lib/router/layer.js:95:5)
at next (/home/ubuntu/workspace/node_modules/express/lib/router/route.js:131:13)
at Route.dispatch (/home/ubuntu/workspace/node_modules/express/lib/router/route.js:112:3)
at Layer.handle [as handle_request] (/home/ubuntu/workspace/node_modules/express/lib/router/layer.js:95:5)
at /home/ubuntu/workspace/node_modules/express/lib/router/index.js:277:22
at Function.process_params (/home/ubuntu/workspace/node_modules/express/lib/router/index.js:330:12)
at next (/home/ubuntu/workspace/node_modules/express/lib/router/index.js:271:10)
at serveStatic (/home/ubuntu/workspace/node_modules/express/node_modules/serve-static/index.js:74:16)我在尝试提交我的文件上传后得到了它。我会假设这意味着它没有正确安装，但我已经尝试了几种方法重新安装。它看起来是最新的：
{ "name": "workspace",
"version": "0.0.0",
"private": true,
"scripts": {
"start": "node ./bin/www"
},
"dependencies": {
"body-parser": "^1.15.2",
"cookie-parser": "~1.4.3",
"debug": "~2.2.0",
"express": "~4.13.4",
"jade": "~1.11.0",
"morgan": "~1.7.0",
"multer": "^1.2.0",
"serve-favicon": "~2.3.0"
}
}下面是我的代码：
应用程序.js
var express = require('express');
var app = express();
var path = require('path');
var multer = require('multer');
var upload = multer({ dest: __dirname + '/public/uploads/'});
var bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(express.static(path.join(__dirname, 'public')));
app.get('/', function (req, res) {
res.sendFile(path.join(__dirname, 'index.html'));
});
app.post('/file-upload', upload.fields('files'), function (req, res, next) {
console.log(req.files);
console.log(req.body);
});
app.listen(process.env.PORT, function () {
console.log('app listening on port ' + process.env.PORT );
});和前端：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<script src="https://code.jquery.com/jquery-2.1.4.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<html>
<body>
<div align='center'>
<form method="post" enctype="multipart/form-data" action="/file-upload" name="upload">
<h1>Upload a file</h1>
<input type="file" id="fileUpload"></input>
<h2>View its Metadata</h2>
<button type="submit" value="submit" id="submit">submit</button>
</form>
</div>
</body>
</html>删除'文件'从upload.fields（）给出这错误
TypeError: Cannot read property 'forEach' of undefined我只尝试上载单个文件，但如果使用
app.post('/file-upload', upload.single('file'), function (req, res, next) {
console.log(req.file);
console.log(req.body);
});
// or upload.single()我的控制台输出
undefined
{}我希望我错过了一些简单的东西。我已经参考了所有这些主题，但还没有找到一个解决方案，对我来说：
hot multer issues
req files undefined
nodejs-multer-is-not-working
express-multer-cannot-read-property-profileimage-of-undefined
multer-callbacks-not-working
multer-node-eacces-error-on-c9-io
multer-configuration-with-app-use-returns-typeerror
Github multer issues thread
2条答案
按热度按时间cnjp1d6j1#
很简单。发帖五分钟后找到的。我把它放在这里以防有人犯同样的错误。
问题出在我的前端：
需要
des4xlb02#
“Multer类型错误：fields.forEach不是函数。”错误为上载。fields（输入参数）中间件输入参数应为数组。
如文档中所述，输入参数应如下所示：[{名称：“虚拟形象”，最大计数：1 }]
请参考文档：https://www.npmjs.com/package/multer
PS：我也得到这个错误，因为我忘记在输入参数中添加数组括号。