Found answer to my question.
I didn’t want to specify each data parameter in the function definition as it could get long. Therefore, I am retrieving them using $_POST
global variable.
I know thats not a good solution, if you know any better let me know.
public function create_document($_files = null){
if(!empty($_files)) {
// process file
}
$data = $_POST;
// process $data is you want
// $data['doc_id']
// $data['case_reference']
.....
.....
}