Decorator to help updating the appropriate wagtail page and/or revision objects

.py

from functools import wraps

def update_page_and_or_revsion(func):
    @wraps(func)
    def func_wrapper(page):
        if page.live:
            if page.has_unpublished_changes:
                # update live page without creating new revsions
                func(page)
                page.save()
                # create new revision based the latest unpublsihed one but don't publish it
                last_revision_as_page = page.revisions.latest('created_at').as_page_object()
                func(last_revision_as_page)
                last_revision_as_page.save_revision()
            else:
                # create new revsion and publish it
                func(page)
                page.save_revision().publish()
        else:
            # create new revsion and don't publish anything
            func(page)
            page.save_revision()
    return func_wrapper

# usage:
@update_page_and_or_revsion
def update(page):
    # page here is either a page or a revision as a page object
    page.field = 'value'
    
update(page)