multer how to access multipart form data before uploading files

0
votes

I am trying to handle form which submits text fields and upload files, I am using multer to handle file uploads and express-validator to validate other fields.

With multipart form, I can not access req.body before parsing it with multer, which means I have to register multer middleware before other middlewares that need that req.body. I want to know if I can upload the files, only if other fields in the form are valid, is there a way to access req.body without parsing with multer ?

multer setup

const multer = require('multer');

const storage = multer.diskStorage({
  destination: path.join(__dirname, `../public/images/games/temp/`),
  filename: (req, file, cb) => {
    if(file.fieldname === "cover") {
      cb(null, `main.jpg`);  
    } else if(file.fieldname === "screenshots") {
        if(!req.count)
          req.count = 1;

        cb(null, `ss-${req.count++}.jpg`);
    }
  }
});

const upload = multer({storage});

route handler

exports.game_create_post = [
  upload.fields([{name: "cover", maxCount: 1}, {name: "screenshots", maxCount: 10}]),

  body("a field").validator(),
  body("a field").validator(),
  body("a field").validator(),

  // other middlewares...
]
2
node.jsexpressmulter

2 Answers

0
votes

This is how usually posting form is done. We first validate the inputs and if inputs are validated, we work on req.body. However since you are writing your code on the server, you are using vanilla-javascript forms. In this case, you have to pass enctype='multipart/form-data which is an encoding type that allows files to be sent through a POST. Without this encoding the files cannot be sent through post request.

   <form class="product-form" action="/route>" method="POST" enctype="multipart/form-data"></form>
0
votes

You can access the other fields through the your filter like so :

var upload = multer({
    storage: storage,
    fileFilter : (req, file, cb) => { uploadFilter(req, file, cb) },
});

function addComicFilter(req, file, cb) {
    //Here you can access the other fields
    console.log(req.body.title)
    console.log(req.body.description)
    //and you won't get undefined anymore.
    //so do your validation here.
}

app.post('/addComic', upload.single('image'), function (req, res, next) {

 //Can't access other fields through req.body.<Name of the field>
 //You can only access those through the uploadFilter function so your validation
 //should be there.
}