day11：SqlAlchemy ORM

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一.外键关联，relationship() 


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#!/usr/bin/python
#coding=utf-8
__author__ = ‘yaobin‘
 
‘‘‘
使用 ORM/Schema Type/SQL Expression Language/Engine/ConnectionPooling/Dialect 所有组件对数据进行操作。
根据类创建对象，对象转换成SQL，执行SQL。
‘‘‘
 
‘‘‘
relationship() 一对多
relationship(backred)|relationship(back_populates) 双向一对多
‘‘‘
 
 
from sqlalchemy import Table,Column,Integer,ForeignKey,String,create_engine,and_,or_,func,table
from sqlalchemy.orm import relationship,sessionmaker
from sqlalchemy.ext.declarative import declarative_base
 
Base=declarative_base()
 
engine = create_engine("mysql+pymysql://root:[email protected]:3306/test2",echo=False)
 
 
Host2Group = Table(‘host_2_group‘,Base.metadata,
    Column(‘host_id‘,ForeignKey(‘host.id‘),primary_key=True),
    Column(‘group_id‘,ForeignKey(‘group.id‘),primary_key=True),
) #两个列不为空，且唯一
 
 
class Host(Base):
    __tablename__ = ‘host‘
    id = Column(Integer,primary_key=True,autoincrement=True)
    hostname = Column(String(64),unique=True,nullable=False)
    ip_addr = Column(String(128),unique=True,nullable=False)
    port = Column(Integer,default=22)
    group_id = Column(Integer,ForeignKey(‘group.id‘))
 
    #group=relationship("Group")
    group=relationship("Group",backref=‘host_list‘) #backref 双向,这里是大写Group，类似反射,
    #group=relationship("Group",back_populates=‘host_list‘)   #back_populates 单向的，Group里面也要有host_list
 
    def __repr__(self):
        return "<id=%s,hostname=%s,ip_addr=%s>" %(self.id,
                                                  self.hostname,
                                                  self.ip_addr)
 
class Group(Base):
    __tablename__=‘group‘
    id=Column(Integer,primary_key=True)
    name=Column(String(64),unique=True,nullable=False)
    #host_list=relationship("Host",back_populates="group")  #back_populates 单向的，Host里面也要有group
    def __repr__(self):
        return "<id=%s,name=%s>" %(self.id,self.name,)
 
 
 
#Base.metadata.create_all(engine) #创建所有表结构 # 寻找Base的所有子类，按照子类的结构在数据库中生成对应的数据表信息
 
if __name__ == ‘__main__‘:
    SessionCls = sessionmaker(bind=engine) #创建与数据库的会话session class ,注意,这里返回给session的是个class,不是实例
    session = SessionCls() #连接的实例
 
 
 
    # #创建组相关信息
    # g1=Group(name=‘group1‘)
    # g2=Group(name=‘group2‘)
    # g3=Group(name=‘group3‘)
    # g4=Group(name=‘group4‘)
    # g5=Group(name=‘group5‘)
    #
    # session.add_all([g1,g2,g3,g4])
    # session.add(g5)
 
 
 
    #往host表里面增加数据,
    #all_groups=session.query(Group).filter().all()  #查找全部组
    #print(‘---all_groups:--->‘,all_groups)
 
    #把全部组查出来
    query_g1=session.query(Group).filter(Group.name==‘group1‘).first()
    query_g2=session.query(Group).filter(Group.name==‘group2‘).first()
    query_g3=session.query(Group).filter(Group.name==‘group3‘).first()
    query_g4=session.query(Group).filter(Group.name==‘group4‘).first()
    query_g5=session.query(Group).filter(Group.name==‘group5‘).first()
 
    # h1 = Host(hostname=‘localhost‘,ip_addr=‘192.168.1.54‘,port=10000,group_id=query_g1.id)
    # h2 = Host(hostname=‘ubuntu‘,ip_addr=‘192.168.1.55‘,port=10001,group_id=query_g2.id)
    h3 = Host(hostname=‘centos6.5‘,ip_addr=‘192.168.1.56‘,port=10002,group_id=query_g3.id)
    h4 = Host(hostname=‘centos7.1‘,ip_addr=‘192.168.1.57‘,port=10003,group_id=query_g4.id)
    h5 = Host(hostname=‘centos7.2‘,ip_addr=‘192.168.1.58‘,port=10004,group_id=query_g5.id)
    h6 = Host(hostname=‘centos5.8‘,ip_addr=‘192.168.1.59‘,port=10005,group_id=query_g2.id)
    h7 = Host(hostname=‘centos6.2‘,ip_addr=‘192.168.1.60‘,port=10006,group_id=query_g5.id)
    #session.add_all([h1,h2])
    #session.add_all([h3,h4,h5]) #往host表增加数据
    #session.add_all([h6,h7])
 
    #把全部主机信息查出来
    query_h1=session.query(Host).filter(Host.hostname==‘localhost‘).first()
    query_h2=session.query(Host).filter(Host.hostname==‘ubuntu‘).first()
    query_h3=session.query(Host).filter(Host.hostname==‘centos6.5‘).first()
    query_h4=session.query(Host).filter(Host.hostname==‘centos7.1‘).first()
    query_h5=session.query(Host).filter(Host.hostname==‘centos7.2‘).first()
 
 
    #通过relationship(),打印主机对应的主机组
    print(‘query_h1---->group_name:‘,query_h1.group.name)
    print(‘query_h2---->group_name:‘,query_h2.group.name)
    print(‘query_h3---->group_name:‘,query_h3.group.name)
    print(‘query_h4---->group_name:‘,query_h4.group.name)
    print(‘query_h5---->group_name:‘,query_h5.group.name)
 
 
    #通过relationship(),打印主机组对应的主机清单
    print(‘group1---->host_list:‘,query_g1.host_list)
    print(‘group2---->host_list:‘,query_g2.host_list)
    print(‘group3---->host_list:‘,query_g3.host_list)
    print(‘group4---->host_list:‘,query_g4.host_list)
    print(‘group5---->host_list:‘,query_g5.host_list)
 
    session.commit()



二.多对多，通过中间表

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#!/usr/bin/python
#coding=utf-8
__author__ = ‘yaobin‘
 
‘‘‘
使用 ORM/Schema Type/SQL Expression Language/Engine/ConnectionPooling/Dialect 所有组件对数据进行操作。
根据类创建对象，对象转换成SQL，执行SQL。
‘‘‘
 
‘‘‘
没有外键关联了，用中间表，实现多对多
‘‘‘
 
from sqlalchemy import Table,Column,Integer,ForeignKey,String,create_engine,and_,or_,func,table
from sqlalchemy.orm import relationship,sessionmaker
from sqlalchemy.ext.declarative import declarative_base
 
Base=declarative_base()
 
engine = create_engine("mysql+pymysql://root:[email protected]:3306/s12day11",echo=False)
 
 
Host2Group = Table(‘host_2_group‘,Base.metadata,
    Column(‘host_id‘,ForeignKey(‘host.id‘),primary_key=True),
    Column(‘group_id‘,ForeignKey(‘group.id‘),primary_key=True),
) #两个列不为空，且唯一
 
 
class Host(Base):
    __tablename__ = ‘host‘
    id = Column(Integer,primary_key=True,autoincrement=True)
    hostname = Column(String(64),unique=True,nullable=False)
    ip_addr = Column(String(128),unique=True,nullable=False)
    port = Column(Integer,default=22)
    groups=relationship(‘Group‘,secondary=Host2Group,backref=‘host_list‘)  #backref双向,secondary指定中间表，
 
    #group=relationship("Group",backref=‘host_list‘) #backref 双向,这里是大写Group，类似反射,
    #group=relationship("Group",back_populates=‘host_list‘)   #back_populates 单向的，Group里面也要有host_list
 
    def __repr__(self):
        return "<id=%s,hostname=%s,ip_addr=%s>" %(self.id,
                                                  self.hostname,
                                                  self.ip_addr)
 
class Group(Base):
    __tablename__=‘group‘
    id=Column(Integer,primary_key=True)
    name=Column(String(64),unique=True,nullable=False)
    #hosts=relationship("Host")
    #host_list=relationship("Host",back_populates="group")  #back_populates 单向的，Host里面也要有group
    def __repr__(self):
        return "<id=%s,name=%s>" %(self.id,self.name,)
 
 
 
#Base.metadata.create_all(engine) #创建所有表结构 # 寻找Base的所有子类

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