无法使用 express 和 multer 运行 node.js 服务器以在节点中上传文件

Posted 2023-03-07

【中文标题】无法使用 express 和 multer 运行 node.js 服务器以在节点中上传文件

【英文标题】：Cannot run node.js server for upload file in node using express and multer

【发布时间】：2017-03-30 04:22:26

【问题描述】：

我只是 node.js 的初学者 我会尝试用 xpress 制作一个网站，这样我就可以在那里上传任何东西。 我在我的 Mac 上本地设置服务器。

这是我写的代码

server.js

var express = require('express');
var app = express();
var fs = require("fs");

var bodyParser = require('body-parser');
var multers  = require('multer');

app.use(express.static('public'));
app.use(bodyParser.urlencoded( extended: false ));
app.use(multers( dest: '/public/'));

app.get('/index.html', function (req, res) 
   res.sendFile( __dirname + "/" + "index.html" );
)

app.post('/file_upload', function (req, res) 
   console.log(req.files.file.name);
   console.log(req.files.file.path);
   console.log(req.files.file.type);
   var file = __dirname + "/" + req.files.file.name;

   fs.readFile( req.files.file.path, function (err, data) 
      fs.writeFile(file, data, function (err) 
         if( err )
            console.log( err );
            else
               response = 
                  message:'File uploaded successfully',
                  filename:req.files.file.name
               ;
            
         console.log( response );
         res.end( JSON.stringify( response ) );
      );
   );
)

var server = app.listen(8081, function () 
   var host = server.address().address
   var port = server.address().port

   console.log("Example app listening at http://%s:%s", host, port)   
)

这些是错误信息

节点上传.js

/Users/dayatura/Documents/node/node_modules/express/lib/application.js:209 throw new TypeError('app.use() 需要中间件函数'); ^

TypeError: app.use() 需要中间件函数 在 EventEmitter.use (/Users/dayatura/Documents/node/node_modules/express/lib/application.js:209:11) 在对象。 (/Users/dayatura/Documents/node/upload.js:10:5)

在 Module._compile (module.js:570:32)

在 Object.Module._extensions..js (module.js:579:10)

在 Module.load (module.js:487:32)

在 tryModuleLoad (module.js:446:12)

在 Function.Module._load (module.js:438:3)

在 Module.runMain (module.js:604:10)

运行时 (bootstrap_node.js:394:7)

在启动时 (bootstrap_node.js:149:9)

请大家帮忙:)

【问题讨论】：

multer 的使用不正确。请检查文档一次github.com/expressjs/multer

【参考方案1】：

这些是问题：

var multer  = require('multer')(( dest: '/public/'));

那你就可以这样用了。

app.post('/upload', multer.single('image'), function(req, res,next)
//Handle image content here.
console.log(req.file); //to access file
);

【参考方案2】：

根据文档，multer 旨在以下列方式使用：

var express = require('express')
var multer  = require('multer')
var upload = multer( dest: 'uploads/' )

var app = express()

app.post('/profile', upload.single('avatar'), function (req, res, next) 
  // req.file is the `avatar` file
  // req.body will hold the text fields, if there were any
)

app.post('/photos/upload', upload.array('photos', 12), function (req, res, next) 
  // req.files is array of `photos` files
  // req.body will contain the text fields, if there were any
)

有关如何使用任何 multer 方法的文档：https://github.com/expressjs/multer#usage

【参考方案3】：

我刚刚研究了上述链接中的multer 示例。

Js

var express = require('express');
var app     = express();
var fs      = require("fs");
var multers = require('multer');
var upload  = multers( dest: '/public/');

app.get('/index.html', function (req, res) 
   res.sendFile( __dirname + "/" + "index.html" );
)

app.post('/file_upload', upload.array('avatar'), function (req, res) 

   for (var i = 0, len = req.files.length; i < len; i++) 
      var mainFile = req.files[i];
      var file = __dirname + "/" + mainFile.name;

      fs.readFile( mainFile.path, function (err, data) 
         fs.writeFile(file, data, function (err) 
            if( err )
               console.log( err );
               else
                  response = 
                     message :'File uploaded successfully',
                     filename: mainFile.name
                  ;
               
            console.log( response );
            res.end( JSON.stringify( response ) );
         );
      );
   
)

var server = app.listen(8081, function () 
   var host = server.address().address
   var port = server.address().port

   console.log("Example app listening at http://%s:%s", host, port)   
)

【讨论】：

谢谢，我也有同样的询问。

【参考方案4】：

这是使用 multer 上传文件的完整代码：

var multer  = require('multer')
var storage = multer.diskStorage(
destination: function (req, file, cb) 
    cb(null, './public/app/product') /* here you define destination of uploaded files*/
,
filename: function (req, file, cb) 
    var ext=file.originalname.split(".")
    cb(null, Date.now() +'.'+ext[1]) /* here you set extensions of files when uploaded */

)
var upload = multer( storage: storage );

/* upload.any() method upload any files */
app.post('/backend/product/edit/:id',upload.any(),function (req, res) 



/* req.files are all files that uploaded to server */ 
/* you can see them use res.json(req.files) */ 

)