webform. How to pass variable from php script?

Question

Drupal

I create a form using the webform module. It is necessary in a hidden field (well, or in any other that is written to the database) to pass the value generated by the php script. There is no such thing by default. There are no modules (webform 4.9, drupal7)... How do people who are not too familiar with api get out of the situation?
Actually, I need to pass an argument from the url and tokens did a great job: [current-page:url:args:value:1] But it worked until I added a file upload field to the form. When uploading files, the url is replaced with something else (some kind of Ajax) and the required argument disappears somewhere. Moreover, it somehow happens in a hidden mode, that is, visually my alias address remains the same. Now I don't even know what to think...