when to use pre_save, save, post_save in django?

Question

I see I can override or define pre_save, save, post_save to do what I want when a model instance gets saved.

Which one is preferred in which situation

Answer 1

pre_save

it's used before the transaction saves.

post_save

it's used after the transaction saves.

You can use pre_save for example if you have a FileField or an ImageField and see if the file or the image really exists.

You can use post_save when you have an UserProfile and you want to create a new one at the moment a new User it's created.