multipartHandler and multipartFileHandler should have access to the incoming form.

• Used appropriate template for the issue type
• Searched both open and closed issues for duplicates of this issue
• Title adequately and concisely reflects the feature or the bug

Feature Request

Use Case

By adding the multipartFileHandler or multipartHandler to the bodyParser options, the ordinary process of formidable does not continue (the form.handlePart(part) would not be called anymore). So, we must write our handling function to save the incoming file for example.

server.use(restify.plugins.bodyParser({
  // other options
  // ...
  multipartFileHandler: function (part) {
    const {mime} = part;
    const fileType: string = mime.split('/').pop();
    if (fileType === 'jpg' || fileType === 'png' || fileType === 'jpeg') {
      part.on('data', buffer => {
        fs.writeFile(filePath, buffer, (err) => {
          if (err) {
            console.log(err);
          } else {
            console.log("The file was saved:", filename);
            // form.emit('file', part.name, theSavedFile);
          }
        });
      });
    } else {
      console.log('incorrect file type:', fileType);
    }
  },
  // ...
});

Besides, this method leaves the request.files to be an empty object {}. As we can not call the form.emit('file', part.name, theSavedFile) to ask the formidable: "the {[part.name]: theSavedFile} was successfully received, please add it the the files object".

Example API

We can easily run this snippet and save the file like a piece of cake.

server.use(restify.plugins.bodyParser({
        multiples: true,
        uploadDir,
        multipartFileHandler: function (part, req, form) { // <-- the third argument can be added
                const {mime} = part;
                const fileType: string = mime.split('/').pop();
                if (fileType === 'jpg' || fileType === 'png' || fileType === 'jpeg') {
                        form.handlePart(part); // <--- this line can be used.
                } else {
                        console.log('incorrect file type:', fileType);
                }
        }
})

Are you willing and able to implement this?

It's not so hard. However, I wrote a snippet to inject "form" into the functions.

Start at the bodyParser integration for multipartFileHandler and multipartHandler, then trace how formidable receives each part and populates request.files. Confirm how the callback arguments can expose the incoming form while preserving default handling, and add coverage showing that supported parts are still recorded correctly.