ContentType: text/plain not showing in fields

[neronim1141]

Support plan

• Which support plan is this issue covered by? Community
• Currently blocking your project/work? yes
• Affecting a production system? yes

Context

• Node.js version: 16.13.1
• Release Line of Formidable (Legacy, Current, Next): Next
• Formidable exact version: 3.2.4
• Environment (node, browser, native, OS): node
• Used with (popular names of modules): nextjs, next-connect

What are you trying to achieve or the steps to reproduce?

Im trying to make custom server functionality on nextjs api route,
where i get some request data from game as "multipart/form-data;"
but some of the data has "text/plain" content type.

router.post(async (req, res) => {

  const form = new IncomingForm();
  form.parse(req, (err, fields, files) => {
    console.log(fields);
    console.log(files);
  });

  res.end();
});

export const config = {
  api: {
    bodyParser: false,
  },
};

What was the result you got?

Only the files variable gets populated.
As i needed to disable parser for nextjs
i cant really use req.body.
looping for 'text/plain' mimetype in files and parsing them manualy is not desired either

What result did you expect?

'text/plain' content type parsed into fields variable

[GrosSacASac]

If I understand correctly you want to access files sent as text/plain as if it was another field ?

[GrosSacASac]

This line in the code separates fields from files:
if (!part.mimetype) {

So if you don't have a mimetype it will appear as a field

[neronim1141]

Yes, i managed to do it in an ugly way around

for (let [fileField, filesArray] of Object.entries(files)) {
          const file = (filesArray as File[])[0];
          switch (fileField) {
            case "id":
              id = await fileToString(file.filepath);
              fs.rm(file.filepath);
              break;
            case "extraData":
              extraData = JSON.parse(await fileToString(file.filepath));
              fs.rm(file.filepath);
              break;
            default:
              tile = file;
              break;
          }
        }

but i think as text/plain usually contain string,
if they arent too big maybe they should convert to fileds also?

for disclaimer i cant really change how i receive data, and 'id','extradata' are bassically oneliners
i remember that i used that API with multer some time ago and it was quite simple

[GrosSacASac]

Do you suggest to change formidable ?

[ajmeese7]

@GrosSacASac I would like to see this change as well, I missed this issue but I commented about running into the same problem in #495

[GrosSacASac]

What exactly should change ?

[neronim1141]

if mimetype is text/plain it should be decoded into fields instead of file with provided charset, unless explicity specified,
or allow us to exclude fields from converting to files

[tunnckoCore]

not automatically, and not default behavior

or allow us to exclude fields from converting to files

yep, through option.

[prigaux]

Formidable v1 used to put "a" in fields for:

Invoke-RestMethod -Uri '...' -Method Post -Form  @{ a = 'A'; file = Get-Item -Path '.\foo.txt' }

which sends:

Content-Type: text/plain; charset=utf-8
Content-Disposition: form-data; name="a"

Upgrading to Formidable v2 broke my app.

NB: curl does not send "Content-Type" for non-files.

[prigaux]

Workaround tested on v2:

form.onPart = function (part) {
    if (part.mimetype && !part.headers['content-disposition']?.match(/filename="/)) {
        // we want it to be a "field" (cf https://github.com/node-formidable/formidable/issues/875 )
        delete part.mimetype
    }
    form._handlePart(part);
}

[okcompute]

I have the same issue. My user is calling my API with a C# client. Their multipart/form implemtation always adds the text/plain mimetype. To solve the issue, I have to apply the solution from @prigaux above.

I think this should be fixed upstream in this library, no?

[tunnckoCore]

That's why we even expose internals and allow overriding, so it can be extended. ;)

Converting text/plain to fields by passing some option, could be a good feature too.

Formidable v1 used to put "a" in fields for:

Really strange.. :D Never noticed that, or I forgot it.
That's weird. And what happens when multiple? Multiple as or what? haha.

[CollapsedMetal]

I can confirm that there's no way to succesfully get fields data from submited forms using HttpClient on C#
Had no previous issues using v1
@prigaux workaround works great!

[kkirby]

So, the code used to look at the existence of a filename and would consider it a field if a file name did not exist.

I've been tracing back the code and it used to be what I would consider correct:

formidable/src/incoming_form.js

Line 195 in 15f174f

if (part.filename === undefined) {

But then was changed to look at mime type here: 621e72a

I'm not really sure what the change fixed, but it's not correct. A field is a file if it contains a filename. Otherwise, it's a field. Right??