Flask-SQLAlchemy InvalidRequestError：对象已附加到会话

要编辑帖子,

def post_edit(id,t_id,p_id):
  post = Post.query.filter_by(id=p_id).first()
  if post.author.username == g.user.username:
    form = PostForm(body=post.body)
    if form.validate_on_submit():
      post.body = form.body.data
      db.session.commit()
      return redirect(url_for('thread',id=id,t_id=t_id))
    return render_template('post_edit.html',form=form,title='Edit')
  else:
    flash('Access denied.')
    return redirect(url_for('thread',t_id=t_id))

并删除帖子,

@app.route('/forum=<id>/thr=<t_id>/p=<p_id>/delete',methods=['GET','POST'])
def post_delete(id,p_id):
  post = Post.query.filter_by(id=p_id).first()
  if post.author.username == g.user.username:
    db.session.delete(post)
    db.session.commit()
    return redirect(url_for('thread',t_id=t_id))
  else:
    flash('Access denied.')
    return redirect(url_for('thread',t_id=t_id))

并张贴帖子

@app.route('/forum/id=<id>/thr=<t_id>','POST'])
def thread(id,t_id):
  forum = Forum.query.filter_by(id=id).first()
  thread = Thread.query.filter_by(id=t_id).first()
  posts = Post.query.filter_by(thread=thread).all()
  form = PostForm()
  if form.validate_on_submit():
    post = Post(body=form.body.data,timestamp=datetime.utcnow(),thread=thread,author=g.user)
    db.session.add(post)
    db.session.commit()
    return redirect(url_for('thread',t_id=t_id))
  return render_template('thread.html',forum=forum,posts=posts,title=thread.title)

不幸的是,解决这个问题的唯一可靠方法是重置实际运行应用程序的脚本run.py.

#!bin/python

from app import app
app.run(debug=True,host='0.0.0.0')