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我在sqlalchemy中遇到了以下问题。我在sqlite中创建了三个不同的表,第一个没有任何意义,第二个与第一个和第三个有关系。所以当我想插入第一个和第二个表中的东西时,一切正常。当我想在第三张表格中插入数据时,我会遇到麻烦,当我要按照tutorial中描述的方式进行操作时。这里是我的三个表代码:SQLalchemy中的双关系
第一个表:
# Save_Data_Type.py
from sqlalchemy import ForeignKey
from sqlalchemy import Column, Float, Integer, String
from base import Base
from sqlalchemy.orm import relationship, backref
########################################################################
class Save_Data_Type(Base):
__tablename__ = "save_datas_type"
save_datas_type_id = Column(Integer, primary_key=True)
type_memory = Column(String)
comment = Column(String)
dummy1 = Column(String)
dummy2 = Column(String)
#----------------------------------------------------------------------
def __init__(self, type_memory, comment, dummy1, dummy2):
""""""
self.type_memory = type_memory
self.comment = comment
self.dummy1 = dummy1
self.dummy2 = dummy2
二表
# Save_Data.py
from sqlalchemy import ForeignKey
from sqlalchemy import Column, Float, Integer, String
from base import Base
from sqlalchemy.orm import relationship, backref
########################################################################
class Save_Data(Base):
""""""
__tablename__ = "save_datas"
save_datas_id = Column(Integer, primary_key=True)
save_datas_type_id = Column(Integer,ForeignKey("save_datas_type.save_datas_type_id"))
save_datas_type = relationship("Save_Data_Type", backref=backref("save_datas", order_by=save_datas_id))
value = Column(Float)
comment = Column(String)
dummy1 = Column(String)
#----------------------------------------------------------------------
def __init__(self, value, comment, dummy1):
""""""
self.value = value
self.comment = comment
self.dummy1 = dummy1
三表
# Station.py
from sqlalchemy import ForeignKey
from sqlalchemy import Column, Integer, Boolean, String
from base import Base
from sqlalchemy.orm import relationship, backref
########################################################################
class Station(Base):
""""""
__tablename__ = "stations"
stations_id = Column(Integer, primary_key=True)
name = Column(String)
password = Column(String)
save_datas_id = Column(Integer,ForeignKey("save_datas.save_datas_id"))
save_datas = relationship("Save_Data", backref=backref("stations", order_by=stations_id))
dummy1 = Column(String)
dummy2 = Column(String)
dummy3 = Column(String)
#----------------------------------------------------------------------
def __init__(self, name, password, dummy1, dummy2, dummy3):
""""""
self.name = name
self.password = password
self.dummy1 = dummy1
self.dummy2 = dummy2
self.dummy3 = dummy3
base.py
# base.py
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
所以,如果我要插入DATAS这样的:在数据库中的第三个表
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
import base
from Save_Data_Type import Save_Data_Type
from Save_Data import Save_Data
from Station import Station
engine = create_engine('sqlite:///Database.db', echo=True)
base.Base.metadata.create_all(engine, checkfirst=True)
# create a Session
Session = sessionmaker(bind=engine)
session = Session()
jack = Save_Data_Type("Ring Memory",'In seconds',None,None)
jack.save_datas = [Save_Data(1980,'Sometimes more, sometimes less',None)]
jack.save_datas.stations = [Station('name1','123456',None,None,None)]
session.add(jack)
session.commit()
什么也不写。通常的方式来建立这种关系如何?
由于提前,
约翰内斯
还是更要删除所有关系,并通过查询添加ForeignKey的手工表? – runjojo2 2013-05-08 07:05:43
你的例子有两个名为“Save_Data”的类,应该命名为“Save_Data_Type”吗? – zzzeek 2013-05-08 19:42:06