def save(self, filename=None):
        filename = Path(filename) if filename is not None else self.filename
        with filename.open("w") as f:
            f.write(self.yaml)
def delete_category(category_id):
    category = Category.query.filter_by(id=category_id).first_or_404()

    involved_users = User.query.filter(Forum.category_id == category.id,
                                       Topic.forum_id == Forum.id,
                                       Post.user_id == User.id).all()

    category.delete(involved_users)
    flash(_("Category with all associated forums deleted."), "success")
    return redirect(url_for("management.forums"))