How can i validate file upload using Respect\Validation library?

2

Are you sure you can call the validate() method this way ?
I didn’t know this library, i just browsed their documentation and i couldn’t find any examples calling validate() the same way you do.The thing is you are creating a $newfile variable but you are not using it + validate() seems to take only 1 argument, a value to verify or a string file path in case of mimetype validation.
It means you have to move $newfile before working on it :

//untested code.
//from here, we already have $newfile containing the uploaded file

$filepath = "/a/path/to/receive/uploaded/files/MyFile.pdf";

$newfile->moveTo($filepath); 

$check_file    = v::mimetype('application/pdf')->validate($filepath);
$check_name    = v::stringType()->notEmpty()->length(2, 50)->alpha()->validate($request->getParam('name'));
$check_fname   = v::stringType()->notEmpty()->length(2, 50)->alpha()->validate($request->getParam('fname'));

return ($check_file && $check_name && check_fname);