在Express Route中使用Multer？ （使用MEANJS）

Question

我使用Multer在Express 4中上传图片。但是，这些示例都显示Multer在快递文件中被定义为中间件。我想在我的应用程序路由本身中实际定义一些Multer行为。这可能吗？我需要的最终结果是我的路由功能在将服务器响应发送到浏览器之前识别上传完成的时间，因此可以向用户显示图像（现在我只获得部分图像因为文件还没有完成上传而显示。

当前，工作代码

express.js

// Require Multer as module dependency.
var multer = require('multer');

// Using Multer for file uploads.
app.use(multer({
    dest: './public/profile/img/',
    limits: {
        fieldNameSize: 50,
        files: 1,
        fields: 5,
        fileSize: 1024 * 1024
    },
    rename: function(fieldname, filename) {
        return filename;
    },
    onFileUploadStart: function(file) {
        if(file.mimetype !== 'image/jpg' && file.mimetype !== 'image/jpeg' && file.mimetype !== 'image/png') {
            return false;
        }
    }
}));

server_routes.js

app.route('/users/image').post(server_controller_file.imageUpload);

server_controller_file.js

exports.imageUpload = function(req, res) {
// Check to make sure req.files contains a file, mimetypes match, etc., then send appropriate server response.
};

理想情况下，我的server_controller_file.js会包含一些检查以确保文件完成上传，例如（注意：这是假设的/可取的，而不是实际的工作代码）......

var multer = require('multer');
exports.imageUpload = function(req, res) {
    multer({
        onFileUploadComplete: function(file) {
            res.send();
        }
    });
}

同样，现在节点的异步性质导致浏览器在收到成功响应后认为上传已完成，因此当我更新网址以显示图像时，它只会部分显示。谢谢你的帮助！

Answer 1

实际上你可以用另一种方法做你想做的事情：

var express = require('express');
var multer  = require('multer');
var upload = multer({ dest: './uploads/'});
var app = express();

app.get('/', function(req, res){
  res.send('hello world');
});

// accept one file where the name of the form field is named photho
app.post('/', upload.single('photho'), function(req, res){
    console.log(req.body); // form fields
    console.log(req.file); // form files
    res.status(204).end();
});

app.listen(3000);

Answer 2

好的，我其实刚刚写完原始数据。如果将inMemory设置为true，则会将原始数据发送到req.files.file.buffer。这是最终的，有效的解决方案：

<强> express.js

// Using Multer for file uploads.
app.use(multer({
    dest: './public/profile/img/',
    limits: {
        fieldNameSize: 50,
        files: 1,
        fields: 5,
        fileSize: 1024 * 1024
    },
    rename: function(fieldname, filename) {
        return filename;
    },
    onFileUploadStart: function(file) {
        console.log('Starting file upload process.');
        if(file.mimetype !== 'image/jpg' && file.mimetype !== 'image/jpeg' && file.mimetype !== 'image/png') {
            return false;
        }
    },
    inMemory: true //This is important. It's what populates the buffer.
}));

<强> server_controller_file.js

exports.imageUpload = function(req, res) {
    var file = req.files.file,
        path = './public/profile/img/';

    // Logic for handling missing file, wrong mimetype, no buffer, etc.

    var buffer = file.buffer, //Note: buffer only populates if you set inMemory: true.
        fileName = file.name;
    var stream = fs.createWriteStream(path + fileName);
    stream.write(buffer);
    stream.on('error', function(err) {
        console.log('Could not write file to memory.');
        res.status(400).send({
            message: 'Problem saving the file. Please try again.'
        });
    });
    stream.on('finish', function() {
        console.log('File saved successfully.');
        var data = {
            message: 'File saved successfully.'
        };
        res.jsonp(data);
    });
    stream.end();
    console.log('Stream ended.');
};

Answer 3

我找到了一个busboy的例子：

exports.upload = function (req, res, next) {
   req.busboy.on('file', function (fieldname, file, filename, encoding, mimetype) {
       // ....
   });

   req.pipe(req.busboy);
};

闷闷不乐也是个笨蛋：

 req.pipe(busboy);

https://github.com/expressjs/multer/blob/master/index.js#206