SQLAlchemy - ObjectDeletedError:实例'<Class at ...>'已被删除.救命

Question

我在从数据库中删除行然后添加新行时遇到一些问题.这是代码:

for positionid in form_result['responsibilities']:
   inputdata = form_result['responsibilities'][positionid]

    self.__deleterow(dbmyaccount.Responsibilities, session['authed']['userid'])

    for resp in (i.strip() for i in inputdata.split(',')):
        resp_q = dbmyaccount.Responsibilities(session['authed']['userid'])

        resp_q.positionid     = positionid
        resp_q.responsibility = resp

        Session.add(resp_q)
        Session.commit()

def __deleterow(self, table, user):       
    delete_q = Session.query(table).filter_by(userid=user).first()

    if delete_q:
        Session.query(table).filter_by(userid=user).delete()
        Session.commit()

基本上,我从表中擦除所有用户数据,然后添加他们的新选项.问题是,代码产生了这个错误:

ObjectDeletedError: Instance '<Responsibilities at ...>' has been deleted.

我不知道为什么......从什么我的谷歌搜索已经止跌回升,是因为我已经删除了所有从数据库的数据修改后的职责类产生的误差.虽然用新数据重新初始化它,但我无法弄清楚如何"放手".

我究竟做错了什么？

编辑

这是责任类:

class Responsibilities(Base):

__tablename__ = 'responsibilities'

id             = Column(Integer, primary_key=True)
userid         = Column(Integer, ForeignKey('users.id'))
positionid     = Column(Integer)
responsibility = Column(String(50))

def __init__(self, user=None):
    if user:
        self.userid = user

def __repr__(self):
    return "<Responsibilities({0})".format(self.userid)

这是追溯:

File '<string>', line 2 in save
File 'C:\\Users\\Dave\\Documents\\Python\\pylons\\mydevenv\\lib\\site-packages\\pylons-1.0-py2.6.egg\\pylons\\decorators\\rest.py', line 33 in check_methods
  return func(*args, **kwargs)
File 'C:\\Users\\Dave\\Documents\\Python\\pylons\\website\\website\\controllers\\myaccount.py', line 260 in save
  self.__deleterow(dbmyaccount.Responsibilities, session['authed']['userid'])
File 'C:\\Users\\Dave\\Documents\\Python\\pylons\\website\\website\\controllers\\myaccount.py', line 210 in __deleterow
  Session.query(table).filter_by(userid=user).delete()
File 'C:\\Users\\Dave\\Documents\\Python\\pylons\\mydevenv\\lib\\site-packages\\sqlalchemy-0.6.3-py2.6.egg\\sqlalchemy\\orm\\query.py', line 2031 in delete
  eval_condition(obj)]
File 'C:\\Users\\Dave\\Documents\\Python\\pylons\\mydevenv\\lib\\site-packages\\sqlalchemy-0.6.3-py2.6.egg\\sqlalchemy\\orm\\evaluator.py', line 82 in evaluate
  left_val = eval_left(obj)
File 'C:\\Users\\Dave\\Documents\\Python\\pylons\\mydevenv\\lib\\site-packages\\sqlalchemy-0.6.3-py2.6.egg\\sqlalchemy\\orm\\evaluator.py', line 42 in <lambda>
  return lambda obj: get_corresponding_attr(obj)
File 'C:\\Users\\Dave\\Documents\\Python\\pylons\\mydevenv\\lib\\site-packages\\sqlalchemy-0.6.3-py2.6.egg\\sqlalchemy\\orm\\attributes.py', line 163 in __get__
  instance_dict(instance))
File 'C:\\Users\\Dave\\Documents\\Python\\pylons\\mydevenv\\lib\\site-packages\\sqlalchemy-0.6.3-py2.6.egg\\sqlalchemy\\orm\\attributes.py', line 382 in get
  value = callable_(passive=passive)
File 'C:\\Users\\Dave\\Documents\\Python\\pylons\\mydevenv\\lib\\site-packages\\sqlalchemy-0.6.3-py2.6.egg\\sqlalchemy\\orm\\state.py', line 280 in __call__
  self.manager.deferred_scalar_loader(self, toload)
File 'C:\\Users\\Dave\\Documents\\Python\\pylons\\mydevenv\\lib\\site-packages\\sqlalchemy-0.6.3-py2.6.egg\\sqlalchemy\\orm\\mapper.py', line 2441 in _load_scalar_attributes
  state_str(state))
ObjectDeletedError: Instance '<Responsibilities at ...>' has been deleted.

Answer 1

执行批量删除时,它会从数据库中删除行,但不会更新SQLAlchemy会话中对内存中对象的引用.您可以使用synchronize_session参数来.delete()使其同步会话:

Session.query(table).filter_by(userid=user).delete(synchronize_session='fetch')

请参阅文档中的警告:http://docs.sqlalchemy.org/en/rel_1_0/orm/query.html？ highlight = query.delete #sqlalchemy.orm.query.Query.delete

Answer 2

您尝试执行的代码是有效的，我猜问题在于您的映射器配置，特别是您的用户职责关系。您应该做的是cascade为这种关系设置正确的属性，您应该能够按照此处给出的指南[级联项]找出数据库模式的正确设置： http: //www.sqlalchemy.org /docs/orm/relationships.html#the-relationship-api