orm可以将数据库存储的数据封装成对象,同时,如果封装的好的话,所有的数据库操作都可以封装到对象中。这样的代码在组织结构上会非常的清晰,并且相对与使用sql语句在sql注入方面会极具降低。
SQLAlchemy中的映射关系有四种,分别是一对多,多对一,一对一,多对多
实现这种映射关系只需要外键(ForeignKey),和relationship
一对多:
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, CHAR
from sqlalchemy import ForeignKey
from sqlalchemy.orm import relationship, backref
Base = declarative_base()
class Parent(Base):
__table__ = "parent"
id = Column(Integer, Primary_key=True)
name = Column(CHAR(50))
child = relationship("child", backref="parent")
class Child(Base):
__table__ = "child"
id = Column(Integer, Primary_key=True)
name = Column(CHAR(50))
parent_id = Column(Integer,ForeignKey('parent.id'))
多对一:(建议)
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, CHAR
from sqlalchemy import ForeignKey
from sqlalchemy.orm import relationship, backref
Base = declarative_base()
class Parent(Base):
__table__ = "parent"
id = Column(Integer, Primary_key=True)
name = Column(CHAR(50))
class Child(Base):
__table__ = "child"
id = Column(Integer, Primary_key=True)
name = Column(CHAR(50))
parent_id = Column(Integer,ForeignKey('parent.id'))
parent = relationship("parent", backref="child")