AttributeError: 'int' 对象没有属性 '_sa_instance_state' [英] AttributeError: 'int' object has no attribute '_sa_instance_state'

问题描述

我正在使用 Flask 开发论坛模板.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.当我尝试实现与论坛到线程的一对多关系以及与线程到用户的一对多关系时，问题出现了.

I'm working on forum template using Flask. When I attempt creating a new thread in the browser using forms, SQLAlchemy throws an AttributeError. The problem showed up when I tried implementing a one-to-many relationship with Forum-to-Thread and a one-to-many relationship with Thread-to-User.

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'))

所有新的帖子/线程并在 views.py 中处理

All the new posts/threads and handled within views.py

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) 

推荐答案

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:

you want to work with ORM objects, not primary key columns:

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

错误意味着一个整数被解释为一个 ORM 对象.

the error means that an integer is being interpreted as an ORM object.

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