docs: def form_valid(self, redirect_to=None):
          """Save object.
  
          Called when form is validated.
  
          :param redirect_to: real url (created with url_for) to redirect to,
            instead of the view by default.
          """
          session = db.session()
  
          with session.no_autoflush:
              self.before_populate_obj()
              self.form.populate_obj(self.obj)
              session.add(self.obj)
              self.after_populate_obj()
  
          try:
              session.flush()
              self.send_activity()
              session.commit()
  
          except ValidationError as e:
              rv = self.handle_commit_exception(e)
              if rv is not None:
                  return rv
              session.rollback()
              flash(str(e), "error")
              return self.get()
  
          except sa.exc.IntegrityError as e:
              rv = self.handle_commit_exception(e)
              if rv is not None:
                  return rv
              session.rollback()
              logger.error(e)
              flash(_("An entity with this name already exists in the system."), "error")
              return self.get()
  
          else:
              self.commit_success()
              flash(self.message_success(), "success")
  
              if redirect_to:
                  return redirect(redirect_to)
              else:
                  return self.redirect_to_view()