在multer中上传文件之前如何获取body？

Question

在我的项目中，管理员能够上传 MP3 文件并向其提交参数（例如歌曲名称）。

我决定使用 multer 中间件来处理

multipart/form-data

。

我的问题是

req.body.gender

返回始终未定义，因为我必须在

uploadSong

侦听器中使用它。我想在性别为零时上传歌曲。

index.ejs

<form method="post" action="/acp" role="publish" enctype="multipart/form-data">
    <div class="form-group">
        <input type="file" name="song" id="song" accept="audio/mpeg">
    </div>

    <input type="checkbox" name="gender" checked data-toggle="toggle" data-on="Male" data-off="Female">
</form>

app.js

var uploadSong = upload.single('song');
app.post('/acp', isLoggedIn, function (req, res) {

    console.log(req.body.gender); // returns "undefined"

    if(req.body.gender == 0) { // returns "undefined"

        uploadSong(req, res, function (err) {
            if (err) {
                res.send('uploaded');
                return;
            }
            res.redirect('/');

        });
    
    }
});

Answer 1

(A) multer 不可能。

(B) 使用busboy。它使用流来解析表单数据，因此您可以在文件上传之前获取表单元素值，并且字段可作为事件使用。

(C) 另一种解决方案（如果您更喜欢使用 multer）是使用 multer 但添加标头以发送参数值以在文件上传之前进行检查。请求到达服务器后，标头就可用。

Answer 2

通过使用 multer form-data 解析器，您可以在 multer 启动之前解析表单并访问

req.body

，只需注册此应用程序中间件即可：

import * as multer from "multer";

// parse form-data
app.use(multer().any());

Answer 3

这是我的示例代码，运行良好，如果您需要进一步的解释，请告诉我。希望有帮助。

var Hotel = require('../models/hotel');
    var path = require('path');
    var multer = require('multer');
    var uplodedImages = [];

    var storageHotelGallery = multer.diskStorage({
      destination: function (req, file, cb) {
        cb(null, './uploads/hotelGallery');
      },
      filename: function (req, file, cb) {
        console.log(req.body);
        var newFileName = Date.now() + path.extname(file.originalname);
        req.newFileName = newFileName;
        cb(null, newFileName);
        uplodedImages.push(newFileName);
      }
    });
    var uploadHotelGallery = multer({ storage: storageHotelGallery}).fields([{ name: 'imgArr', maxCount: 8 }]);

    module.exports = function(router) {
        // ADD HOTEL BASIC DATA TO CREATE HOTEL OBJECT
        router.post('/createHotelStep1', function(req, res) {
            if( req.body.name == null || req.body.name == '' ) {
                res.json({ success: false, message: "Hotel name required" });
                res.end();
            }
            else if( req.body.addressline1 == null || req.body.addressline1 == '' ) {
                res.json({ success: false, message: "Address line 1 is required" });
                res.end();
            }
            else if( req.body.city == null || req.body.city == '') {
                res.json({ success: false, message: "City is required" });
                res.end();
            }
            else {
                var hotel = new Hotel();
                hotel.name = req.body.name;
                hotel.addressline1 = req.body.addressline1;
                hotel.addressline2 = req.body.addressline2;
                hotel.phone = req.body.phone;
                hotel.city = req.body.city;
                hotel.email = req.body.email;
                hotel.save(function(err) {
                    if (err) {
                        res.json({ success: false, message: "Unable to Complete Hotel Step 1" });
                    } else {
                        res.json({ success: true, message: 'Create Hotel Step 1 Complete', _id : hotel._id });
                    }
                });
            }
        });

        router.post('/createHotelGallery', function (req, res, next) {
            uplodedImages = [];
            uploadHotelGallery(req, res, function(err) {
                if(err) {
                    res.json({ success: false, message: 'Could not upload images'});
                    res.end();
                }
                else {
                    Hotel.findOne({ _id:req.body._id }).populate('users').exec(function (err, hotel) {
                    if (err) {
                        res.json({ success: false, message: 'Could not save uploaded images to database'});
                        res.end();  
                    }
                    else {
                        for(var x=0; x<uplodedImages.length; x++)
                            hotel.images.push(uplodedImages[x]);
                        hotel.save();
                        res.json({ success: true, message: 'Gallery image uploaded' });
                        res.end();
                    }
                    });
                }
            });
        });

        return router;
    }

Answer 4

这是我的示例代码，运行良好

const upload = multer({
  storage,
  fileFilter(req, file, cb) {
    if(req.body.name===''){
      return cb(new Error('Invalid name'), false)
    }
    const extname = path.extname(file.originalname).toLowerCase() === '.gz'
    const mimetype = file.mimetype === 'application/x-gzip'
    if (mimetype && extname) {
      return cb(null, true)
    } else {
      return cb(new Error('Invalid mime type'), false)
    }
  },
})

Answer 5

使用 api 端点作为查询参数发送。它将在图像之前收到。 😊