Save the created_by and last_modified_by fields based on the current admin user.

def save(self, *args, **kwargs):
        """
        Save the created_by and last_modified_by fields based on the current admin user.
        """
        if not self.instance.id:
            self.instance.created_by = self.user
        self.instance.last_modified_by = self.user
        return super(ChangeableContentForm, self).save(*args, **kwargs)