#播放
@home.route('/play/<int:id>/<int:page>/',methods=['GET','POST'])
# @user_login_req
def play(id=None,page=None):
    movie=Movie.query.join(Tag).filter(
        Movie.tag_id==Tag.id,
        Movie.id==int(id)
    ).first_or_404()
    if page is None:
        page=1
    page_data=Comment.query.join(User).filter(
        Comment.movie_id==id,
        Comment.user_id==User.id,
    ).order_by(Comment.addtime.desc()).paginate(page=page,per_page=2)
    movie.playnum += 1
    form=CommentForm()
    if form.validate_on_submit()and 'user' in session:
        data=form.data
        comment=Comment(
            content=data['content'],
            movie_id=int(id),
            user_id=session['user_id'],
        )
        db.session.add(comment)
        db.session.commit()
        movie.commentnum+=1
        flash('添加评论成功！','ok')
        return redirect(url_for('home.play',id=id,page=1))
    db.session.add(movie)
    db.session.commit()
    return render_template('home/play.html',movie=movie,form=form,page_data=page_data)

老师，添加评论后数据库中commentnum并不会增加，一直为0？？