在快速路线上使用Multer？ （使用MEANJS） [英] Use Multer in Express Route? (Using MEANJS)

问题描述

我正在使用 Multer 在Express 4中上传图像。但是，这些示例都显示Multer被定义在将文件作为中间件。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发送服务器响应到浏览器之前识别上传完成，因此可以向用户显示图像（现在我只显示部分图像，因为该文件尚未完成上传）。

I'm using Multer to upload images in Express 4. However, the examples all show Multer being defined in the express file as Middleware. I'd like to actually define some of the Multer behaviors in my app routing itself. Is this possible? The end result that I need is for my route function to recognize when the upload is finished before it sends the server response to the browser, so an image can be displayed to the user (right now I'm only getting a partial image displayed because the file hasn't finished uploading yet).

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将包含一些检查，以确保文件完成上传，例如（注意：这是假设/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();
        }
    });
}

再次，现在节点的异步性质导致浏览器认为一旦收到成功的响应，上传就会完成，所以当我更新url来显示图像时，它只会部分显示。感谢您的帮助！

Again, right now the async nature of node is causing the browser to think the upload is complete as soon as it receives a successful response, so when I update the url to display the image, it only partially displays. Thanks for the help!

推荐答案

好的，我实际上刚刚写了原始数据。如果您将 inMemory 设置为 true ，则将原始数据发送到req.files.file.buffer。这是最终的工作解决方案：

OK, I actually just ended up writing the raw data. If you set inMemory to true, it sends the raw data to req.files.file.buffer. Here's the final, working solution:

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.
}));

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.');
};

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