beginner's question on customizing generic UpdateView

I’ve got a model that stores part of its information in the DB, and part on the file system.
I would like to use the generic UpdateView, adding some fields for the information on the file system.
So I need to

  • add fields to the form
  • initialize those fields (using the object’s DB info to access the file system)
  • retrieve those fields (on post) to save the new info to the file system

I’m quite lost looking for pointers in the doc on what methods I should redefine (surely because I’m new to django)

any help please ?

  • on the “add fields”, the solution is to add it to the derived ModelForm (but beware not to its Meta)
  • on the “retrieve on post”, the solution is to override form_valid() in the derived UpdateView

…still looking for the initialization part

  • on “init using object” : override get_initial in derived UpdateView (the target object is in self)