我有两个数据库,我正在使用SQLAlchemy与Python一起使用,数据库共享表名,因此运行代码时收到错误消息。sqlalchemy具有相同表名称的多个数据库不起作用
的错误信息是:
sqlalchemy.exc.InvalidRequestError: Table 'wo' is already defined for this MetaData instance. Specify 'extend_existing=True' to redefine options and columns on an existing Table object.
简化代码如下:
from sqlalchemy import create_engine, Column, Integer, String, DateTime, ForeignKey
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relationship, backref
from mysql.connector.connection import MySQLConnection
Base = declarative_base()
def get_characterset_info(self):
return self.get_charset()
MySQLConnection.get_characterset_info = MySQLConnection.get_charset
mysqlengine = create_engine('mysql+mysqlconnector://......../mp2', echo=True)
MYSQLSession = sessionmaker(bind=mysqlengine)
mysqlsession= MYSQLSession()
MP2engine = create_engine('mssql+pyodbc://......../mp2', echo=True)
MP2Session = sessionmaker(bind=MP2engine)
mp2session= MP2Session()
class MYSQLWo(Base):
__tablename__= 'wo'
wonum = Column(String, primary_key=True)
taskdesc = Column(String)
comments = relationship("MYSQLWocom", order_by="MYSQLWocom.wonum", backref='wo')
class MYSQLWocom (Base):
__tablename__='wocom'
wonum = Column(String, ForeignKey('wo.wonum'), primary_key=True)
comments = Column(String, primary_key=True)
class MP2Wo(Base):
__tablename__= 'wo'
wonum = Column(String, primary_key=True)
taskdesc = Column(String)
comments = relationship("MP2Wocom", order_by="MP2Wocom.wonum", backref='wo')
class MP2Wocom (Base):
__tablename__='woc'
wonum = Column(String, ForeignKey('wo.wonum'), primary_key=True)
location = Column(String)
sublocation1 = Column(String)
texts = Column(String, primary_key=True)
我该如何处理与具有相同的表结构的数据库?我猜它与MetaData实例有关,但是当谈论类声明和古典用法的差异时,SQLAlchemy文档变得有点混乱..
我删除随机')'在源代码中我认为是一个错字,如果它不是可以恢复。 – GWW
我有答案: 由于实际上表格有稍微不同的结构,解决方案是简单地创建一个单独的声明基础。如果表格确实具有相同的结构,我不需要创建一个单独的类。 'Base = declarative_base()' 'Base2 = declarative_base()' – dangel