I am looking to prepopulate a page full of fields (not webform) from a json file. There are a lot of fields on the page and some of them contain a lot of info, so it doesnt appear that it is practical to use the prepopulate module. https://www.drupal.org/project/prepopulate
I have a rather long form that the user needs to fill in, but they likely already have the required info in a file on their pc. To save them manually filling it in, the user will upload a file which will then be processed (externally) and a json will be returned. The form will then be filled in automatically based on the processed results. Some of these fields are paragraphs with multiple fields.
If possible it would be ideal if this can be done without drupal module development. I've looked at how this can be done with js and possibly some python on the server side, but I'm still a little lost when it comes to how drupal handles these things.
Any guidance on where to go?