How to handle auto_now=True fields?

[LincolnPuzey]

There have been two PRs (#152 and #194) suggesting some sort of change to the current behavior which is that:

a) Fields with auto_now=True do not appear as dirty - they won't appear in .get_dirty_fields()
b) And so by extension .save_dirtyfields() doesn't include them in update_fields so they are not updated by this method.

Some options we have are:

1. Make no changes and document behavior. Users can override save() / save_dirty_fields() / get_dirty_fields() if they need something else.
2. Keep (a) the same but make some change to save_dirty_fields. E.g. my suggestion here
3. Make auto_now=True fields appear as dirty so save_dirtyfields() will update them.

There was a similar issue and discussion in Django here: https://code.djangoproject.com/ticket/22981 where the resolution was to make no changes.

[LincolnPuzey]

@romgar Do you have a strong preference for any option?

I think we should not change the behavior of (a). I would be open to doing something in save_dirty_fields() or not making any change at all.

[sidmitra]

@LincolnPuzey 4th option could be to add a parameter? include_auto_now=True to save_dirty_fields() ? Your comment on the other PR also makes sense.

For the second part of your change - adding the option to save_dirty_fields(), rather than add a special case for auto_now fields, I think adding a generic extra_update_fields argument, eg

But perhaps Option 1 is also ok. We'll try it out and add comments here on any issues we encounter.