我得到:
sqlalchemy.exc.InvalidRequestError: Object '<DBEdge at 0x103c4a190>' is already attached to session '1' (this is '2')
在这条线上
session.add(edge)
当我试着运行这个:
def findOrCreateEdge(self,user1,user2): #user1 is followed by user2
if user1.id>user2.id:
user1, user2 = user2, user1
kind = 2
else:
kind = 1
edge = self.findEdge(user1,user2)
if edge:
if edge.kind==1 and kind==2:
edge.kind = 3
if edge.kind==2 and kind==1:
edge.kind = 3
return edge
else:
edge = DBEdge(user1,user2)
edge.kind = kind
user1.edge_count = user1.edge_count + 1
user2.edge_count = user2.edge_count + 1
#session.save(edge) # we don't flush edges here, because it gives us a huge speedup to do a bunch at once then flush.
try:
session.add(edge)
session.commit()
except:
session = Session()
session.add(edge)
session.commit()
return edge
问题在于将边添加两次,一次添加到第一个会话,然后在出现异常时添加到第二个会话。我不知道您到底想在这里实现什么,但是与其粗暴地将边缘塞进一个新会话,不如您调查错误并解决问题。或者,您可能希望回滚上一个会话并重新启动它,然后将边添加到该会话中。
在已经有会话的情况下创建一个新会话几乎总是一个错误(除非上下文本身发生了更改,但这里似乎不是这样)。
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