SQL Alchemy没有事务开始错误

Question

我运行以下代码

db = create_engine('sqlite:///tracking_test.db')
db.echo= True
metadata = MetaData(db)
session = create_session(bind=db)
#define tables, if they exist sqlalchemly will find them and sycn otherwise they will be created
delivered= Table('delivered', metadata,
    Column('delivered_id',Integer,primary_key=True),
    Column('domain',String(200)),
    Column('path',String(500)),
    )

class Delivered(object):        
    def __init__(self,obj):
        self.domain=u'%s' % obj.get("dm","")
        self.path=u'%s' % obj.get("pth","")


report1t = Table('clicked', metadata,
    Column('clicked_id',Integer,primary_key=True),
    Column('domain',String(200)),
    Column('path',String(500)),

)

class report1(object):
    def __init__(self,obj):
        self.domain=u'%s' % obj.get("dm","")
        self.path=u'%s' % obj.get("pth","")


metadata.create_all()
mapper(report1, report1t)
mapper(Delivered,delivered)
result= {}#some dict
newT = Delivered(result)
if newT:
    session.add(newT)
    session.commit()
    session.flush()

我收到此错误sqlalchemy.exc.InvalidRequestError:没有开始事务.

会议词典说:

{'autocommit': True, 'autoflush': False, 'transaction': None, 'hash_key': 4317750544, 'expire_on_commit': False, '_new': {<sqlalchemy.orm.state.InstanceState object at 0x101a79ad0>: <__main__.adDelivered object at 0x101a799d0>}, 'bind': Engine(sqlite:///adtracking_test.db), '_deleted': {}, '_flushing': False, 'identity_map': {}, 'dispatch': <sqlalchemy.event.SessionEventsDispatch object at 0x101a82f90>, '_enable_transaction_accounting': True, '_identity_cls': <class 'sqlalchemy.orm.identity.WeakInstanceDict'>, 'twophase': False, '_Session__binds': {}, '_query_cls': <class 'sqlalchemy.orm.query.Query'>}

谁知道我做错了什么？

谢谢,CG

Answer 1

如果您发布完整的回溯将会很有帮助.但是,我认为问题在于您创建会话的方式.我认为你应该使用sessionmaker而不是create_session(我之前从未见过这个功能,而且我没有看到它记录在任何地方). sessionmaker创建一个新Session类,您需要实例化它.所以:

Session = sessionmaker(bind=db)
session = Session()
...
session.add(newT)

Answer 2

执行以下代码行提到的提交时出现类似错误“没有开始事务”：

    db_session = scoped_session(sessionmaker(autocommit=False, autoflush=False, bind=engine))
    db_session.add(target)
    db_session.commit()

就我而言，发生错误是因为我将自动提交设置为 True 并尝试提交（）。要解决此问题，已将 autocommit 设置为 False，如下面的代码所示。

db_session = scoped_session(sessionmaker(autocommit=False, autoflush=False, bind=engine))

谢谢，卡西克