How to set custom header on form-data item?

Question

I am sending a multipart data from a nodeJS route as a response. I used form-data library to accomplish, my requirement is to send additional header information for all binary data.

I tried the following

 router.get('/getdata', async (req, res, next) => {
    var form = new FormData();
    var encodedImage2 = fs.readFileSync('./public/image2.png');

    var CRLF = '\r\n';
    var options = {
        header: CRLF + '--' + form.getBoundary() + CRLF + 'X-Custom-Header: 123' + CRLF + CRLF
    };
    form.append('image2.png', encodedImage2, options);

    res.set('Content-Type', 'multipart/form-data; boundary=' + form.getBoundary());
    form.pipe(res);
 });

in the output I get only the header

X-Custom-Header: 123

without the option object I can get

Content-Disposition: form-data; name="image2.png"
Content-Type: application/octet-stream

I need an output headers something like

Content-Disposition: form-data; name="image2.png"
Content-Type: application/octet-stream
X-custom-Header: 123

Answer 1

I found the solution myself, and its very simple. Its posible to set custom headers in the options object header property

router.get('/getdata', async (req, res, next) => {
    var form = new FormData();
    var encodedImage2 = fs.readFileSync('./public/image2.png');
    var options = {
        header: {
           'X-Custom-Header': 123
       }
    };
    form.append('image2.png', encodedImage2, options);

    res.set('Content-Type', 'multipart/form-data; boundary=' + form.getBoundary());
    form.pipe(res); 
});