Javascript Node.js和Multer-在回调函数（req，res）中处理上传文件的目的地

我是Node.js新手，最近遇到了一个简单的问题

我正在使用

multer

模块上传图像。 在我的web应用程序中，所有用户都有一个唯一的id，我希望上传的图像存储在一个基于其id命名的目录中

例如：

.public/uploads/3454367856437534

这是我的

routes.js

文件的一部分：

// load multer to handle image uploads
var multer  = require('multer');
var saveDir = multer({
  dest: './public/uploads/' + req.user._id, //error, we can not access this id from here
  onFileUploadStart: function (file) { 
  return utils.validateImage(file); //validates the image file type
  }
});

module.exports = function(app, passport) {

app.post('/', saveDir, function(req, res) {
                id     : req.user._id,  //here i can access the user id
    });
});

}

如何访问回调

函数（req，res）

外部的

req.user.\u id

属性， 因此，我可以将它与

multer

一起使用，根据id生成正确的目录

编辑以下是我尝试过但没有成功的方法：

module.exports = function(app, passport) {

app.post('/', function(req, res) {
    app.use(multer({
        dest: './public/uploads/' + req.user._id
    }));
});

}

---

更新

自从我发布最初的答案以来，很多事情都发生了变化

使用

multer 1.2.1

您需要使用

DiskStorage

指定存储文件的位置和方式

默认情况下，multer将使用操作系统的默认目录。在我们的例子中，因为我们对位置很挑剔。我们需要确保文件夹存在，然后才能将文件保存在那里

注意：当作为函数提供目的地时，您负责创建目录

更多

fs extra

用于创建目录

原始答案

你可以用

函数重命名要放置上载文件的目录

可从以下网址获得：

---

您可以通过引用输入名称来解决此问题，并在分配路径之前重命名路径

app.use(multer({ dest: './standard_folder/',
    rename: function (fieldname, filename) {

      var pathHelper ='';
      if(fieldname =='otherKindOfFolderNeeded'){
        pathHelper = '../../path/to/other/folder/';
      }
      return pathHelper+uuid.v4()+Date.now();
    },
    onFileUploadStart: function (file) {
      console.log(file.originalname + ' is starting ...')
    },
    onFileUploadComplete: function (file) {
      console.log(file.fieldname + ' uploaded to  ' + file.path)
      done=true;
    }
  })
);

---

您可以使用multer来处理上传目录的动态创建。发送文件名之前，应调用输入参数（要为其创建目录）

var express = require('express');
var app = express();
var multer = require('multer');
var fs = require('fs');
var mkdirp = require('mkdirp');
var bodyParser = require('body-parser');
app.use(bodyParser.json({limit: '5mb'}));
app.use( bodyParser.json() );       // to support JSON-encoded bodies
app.use(bodyParser.urlencoded({     // to support URL-encoded bodies
    extended: true,
    limit: '5mb'
}));

var storage =   multer.diskStorage({
    destination: function (req, file, callback) {
        var Id = req.body.id;
        upload_path = "./"+Id;
        mkdirp(upload_path, function (err) {
            if (err) console.error(err)
            else {
                console.log('Directory created');
                //setting destination.
                callback(null, upload_path);
            }
        });

    },
    filename: function (req, file, callback) {
        callback(null, file.orginalname)
    }
});
//multer setting and getting paramaters.
var upload = multer({ storage : storage }).single('upload_file');

//creating request for upload file
app.post('/uploadFile', function(req, res){
    res.set({ 'content-type': 'application/json; charset=utf-8' });
    res.header("Content-Type", "application/json; charset=utf-8");
    res.header("Access-Control-Allow-Origin", "*");
    res.charset = 'utf-8';
    //function upload_process(){
    upload(req, res, function(err){
        if(err){
            console.log('Error-->');
            console.log(err);
            res.json({"status": "Failure", "message":'There was a problem uploading your files.'+err});
            return;
        }
        else{
            console.log("fieldname"+req.files.length);
            if( req.files.length != 0){
                res.json({"status" : "Success", "message":'Your files are uploaded.'});
                console.log('File uploaded!');
            }
            else{
                console.log("No file uploaded. Ensure file is uploaded.");
                res.json({"status" : "Failure", "message" : 'No file uploaded. Ensure file is uploaded.'});

            }
        }
    });

});

});

---

希望这有帮助！快乐编码

你不能。但是你可以把你的multer代码放到

应用程序中。get

我已经试过了，multer只是创建了一个没有任何图像的空白目录。如果你认为可以这样做，请发一个例子，谢谢。我可以试试，但是我需要你的图片的代码。确切的代码是什么？multer负责上传部分的工作。如果您是指用于文件类型验证的代码，请忽略它。否当以这种方式使用changeDest时，从user.req获取图像的代码仍然未定义。@Gustus，整个post req正文或req中的特定参数变为未定义？

app.use(multer({ dest: './standard_folder/',
    rename: function (fieldname, filename) {

      var pathHelper ='';
      if(fieldname =='otherKindOfFolderNeeded'){
        pathHelper = '../../path/to/other/folder/';
      }
      return pathHelper+uuid.v4()+Date.now();
    },
    onFileUploadStart: function (file) {
      console.log(file.originalname + ' is starting ...')
    },
    onFileUploadComplete: function (file) {
      console.log(file.fieldname + ' uploaded to  ' + file.path)
      done=true;
    }
  })
);

var express = require('express');
var app = express();
var multer = require('multer');
var fs = require('fs');
var mkdirp = require('mkdirp');
var bodyParser = require('body-parser');
app.use(bodyParser.json({limit: '5mb'}));
app.use( bodyParser.json() );       // to support JSON-encoded bodies
app.use(bodyParser.urlencoded({     // to support URL-encoded bodies
    extended: true,
    limit: '5mb'
}));

var storage =   multer.diskStorage({
    destination: function (req, file, callback) {
        var Id = req.body.id;
        upload_path = "./"+Id;
        mkdirp(upload_path, function (err) {
            if (err) console.error(err)
            else {
                console.log('Directory created');
                //setting destination.
                callback(null, upload_path);
            }
        });

    },
    filename: function (req, file, callback) {
        callback(null, file.orginalname)
    }
});
//multer setting and getting paramaters.
var upload = multer({ storage : storage }).single('upload_file');

//creating request for upload file
app.post('/uploadFile', function(req, res){
    res.set({ 'content-type': 'application/json; charset=utf-8' });
    res.header("Content-Type", "application/json; charset=utf-8");
    res.header("Access-Control-Allow-Origin", "*");
    res.charset = 'utf-8';
    //function upload_process(){
    upload(req, res, function(err){
        if(err){
            console.log('Error-->');
            console.log(err);
            res.json({"status": "Failure", "message":'There was a problem uploading your files.'+err});
            return;
        }
        else{
            console.log("fieldname"+req.files.length);
            if( req.files.length != 0){
                res.json({"status" : "Success", "message":'Your files are uploaded.'});
                console.log('File uploaded!');
            }
            else{
                console.log("No file uploaded. Ensure file is uploaded.");
                res.json({"status" : "Failure", "message" : 'No file uploaded. Ensure file is uploaded.'});

            }
        }
    });

});

});