auto naming a PDF from a text box contents

I have a form that needs to be named the same as the contents of a text box (named AGET).

I need to make a "SAVE" button at the end of the form that autofills the filename the same as the text box contents.

For example, I enter AGET000111 into the AGET text box, then hit the SAVE button - I need the pdf filename to auto name as AGET000111.pdf

is this possible?

thanks