AttributeError：“int”对象没有属性“_sa_instance_state”答案

【问题标题】：AttributeError: 'int' object has no attribute '_sa_instance_state'AttributeError：“int”对象没有属性“_sa_instance_state”
【发布时间】：2013-04-15 15:03:46
【问题描述】：

我正在使用 Flask 制作论坛模板。当我尝试使用表单在浏览器中创建一个新线程时，SQLAlchemy 会抛出一个 AttributeError。当我尝试使用 Forum-to-Thread 实现一对多关系以及使用 Thread-to-User 实现一对多关系时，问题就出现了。

models.py

class User(db.Model):
  id = db.Column(db.Integer, primary_key=True)
  username = db.Column(db.String(32), index=True, unique=True)
  password = db.Column(db.String(32), index=True)
  email = db.Column(db.String(120), index=True, unique=True)
  role = db.Column(db.SmallInteger, default=ROLE_USER)

  posts = db.relationship('Post', backref='author', lazy='dynamic')

class Forum(db.Model):
  id = db.Column(db.Integer, primary_key=True)
  title = db.Column(db.String(128))
  description = db.Column(db.Text)

  threads = db.relationship('Thread', backref='forum', lazy='dynamic')

class Thread(db.Model):

  id = db.Column(db.Integer, primary_key=True)
  title = db.Column(db.String(128))
  author= db.Column(db.String(32))
  timestamp = db.Column(db.DateTime)
  forum_id = db.Column(db.Integer, db.ForeignKey('forum.id'))

  posts = db.relationship('Post', backref='thread', lazy='dynamic')

class Post(db.Model):

  id = db.Column(db.Integer, primary_key=True)
  body = db.Column(db.Text)
  timestamp = db.Column(db.DateTime)
  thread_id = db.Column(db.Integer, db.ForeignKey('thread.id'))
  user_id = db.Column(db.Integer, db.ForeignKey('user.id'))

所有新帖子/线程并在views.py中处理

views.py

@app.route('/forum/id=<id>/submit', methods=['GET','POST'])
@login_required
def new_thread(id):
  form = ThreadForm()
  forum = Forum.query.filter_by(id=id).first()
  if form.validate_on_submit():
    thread = Thread(title=form.title.data,
                    author=g.user.username,
                    timestamp=datetime.utcnow())
    db.session.add(thread)
    db.session.flush()
    post = Post(body=form.body.data,
                timestamp=datetime.utcnow(),
                thread=thread.id,
                author=g.user.id)
    db.session.add(post)
    db.session.commit()
    flash('Post successful.')
    return redirect(url_for('forum_index', id=id))
  return render_template('forum/thread_submit.html', title=forum.title, form=form)

【问题讨论】：

标签： python sqlalchemy flask one-to-many flask-sqlalchemy

【解决方案1】：

问题是这样的：

post = Post(body=form.body.data,
            timestamp=datetime.utcnow(),
            thread=thread.id,
            author=g.user.id)

您想使用 ORM 对象，而不是主键列：

post = Post(body=form.body.data,
            timestamp=datetime.utcnow(),
            thread=thread,
            author=g.user)

错误意味着整数被解释为 ORM 对象。

【讨论】：