UPPY + tus-php: getting json from server

Need advice.

Tried to put data in a custom header but I can’t access it on ‘upload-success’ event. Maybe I miss something small.

I need to get some additional data (json) from the server when single file uploading is finished. It’s TUS on the backend. So I’m not using Uppy with XHR.

What is the best approach to solve the task?