Python sqlalchemy:插入到联接表中
我尝试将记录添加到联接的继承表中。 由于某种原因,我无法理解,依赖表没有插入到Python sqlalchemy:插入到联接表中,python,sqlalchemy,Python,Sqlalchemy,我尝试将记录添加到联接的继承表中。 由于某种原因,我无法理解,依赖表没有插入到 ## Inheritance test case. from sqlalchemy import create_engine, Column, Integer, String, ForeignKey from sqlalchemy.orm import Session, relationship, backref from sqlalchemy.ext.declarative import declarative_b
## Inheritance test case.
from sqlalchemy import create_engine, Column, Integer, String, ForeignKey
from sqlalchemy.orm import Session, relationship, backref
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class Employee(Base):
__tablename__ = 'personnel'
__mapper_args__ = { 'polymorphic_on': 'etyp' }
id = Column(Integer, primary_key=True)
name = Column(String(50))
etyp = Column(String(10))
class Engineer(Employee):
__mapper_args__ = { 'polymorphic_identity':'eng' }
__tablename__ = "engineers"
id = Column(Integer, ForeignKey(Employee.id), index=True)
eng_data = Column(String(50))
engine = create_engine('sqlite:///', echo=True)
Base.metadata.create_all(engine)
session = Session(bind=engine)
e1 = Engineer(name="wally", eng_data="lazy guy")
session.add(e1)
session.commit()
# note that the Engineer table is not INSERTed into
e1 = session.query(Employee).filter_by(name="wally").one()
# the next line triggers an exception because it tries to lookup
# the Engineer row, which is missing
print e1.eng_data
这是Python 2.7、sqlalchemy 0.9.4 Debian测试。将engineers.id作为主键将解决问题:
class Engineer(Employee):
# ...
id = Column(Integer, ForeignKey(Employee.id), primary_key=True)