Python学习笔记day11

SqlAlchemy ORM　　

SQLAlchemy是Python编程语言下的一款ORM框架，该框架建立在数据库API之上，使用关系对象映射进行数据库操作，简言之便是：将对象转换成SQL，然后使用数据API执行SQL并获取执行结果

Dialect用于和数据API进行交流，根据配置文件的不同调用不同的数据库API，从而实现对数据库的操作，如：

MySQL-Python
    mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>
  
pymysql
    mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>]
  
MySQL-Connector
    mysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname>
  
cx_Oracle
    oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...]
  
更多详见：http://docs.sqlalchemy.org/en/latest/dialects/index.html

步骤一：

使用 Engine/ConnectionPooling/Dialect 进行数据库操作，Engine使用ConnectionPooling连接数据库，然后再通过Dialect执行SQL语句。

#!/usr/bin/env python
# -*- coding:utf-8 -*-
  
from sqlalchemy import create_engine
  
  
engine = create_engine("mysql+mysqldb://root:123@127.0.0.1:3306/s11", max_overflow=5)
  
engine.execute(
    "INSERT INTO ts_test (a, b) VALUES ('2', 'v1')"
)
  
engine.execute(
     "INSERT INTO ts_test (a, b) VALUES (%s, %s)",
    ((555, "v1"),(666, "v1"),)
)
engine.execute(
    "INSERT INTO ts_test (a, b) VALUES (%(id)s, %(name)s)",
    id=999, name="v1"
)
  
result = engine.execute('select * from ts_test')
result.fetchall()

步骤二：

使用 Schema Type/SQL Expression Language/Engine/ConnectionPooling/Dialect 进行数据库操作。Engine使用Schema Type创建一个特定的结构对象，之后通过SQL Expression Language将该对象转换成SQL语句，然后通过 ConnectionPooling 连接数据库，再然后通过 Dialect 执行SQL，并获取结果。

#!/usr/bin/env python
# -*- coding:utf-8 -*-
 
from sqlalchemy import create_engine, Table, Column, Integer, String, MetaData, ForeignKey
 
metadata = MetaData()
 
user = Table('user', metadata,
    Column('id', Integer, primary_key=True),
    Column('name', String(20)),
)
 
color = Table('color', metadata,
    Column('id', Integer, primary_key=True),
    Column('name', String(20)),
)
engine = create_engine("mysql+mysqldb://root@localhost:3306/test", max_overflow=5)
 
metadata.create_all(engine)

增删改查

#!/usr/bin/env python
# -*- coding:utf-8 -*-
 
from sqlalchemy import create_engine, Table, Column, Integer, String, MetaData, ForeignKey
 
metadata = MetaData()
 
user = Table('user', metadata,
    Column('id', Integer, primary_key=True),
    Column('name', String(20)),
)
 
color = Table('color', metadata,
    Column('id', Integer, primary_key=True),
    Column('name', String(20)),
)
engine = create_engine("mysql+mysqldb://root:123@127.0.0.1:3306/s11", max_overflow=5)
 
conn = engine.connect()
 
# 创建SQL语句，INSERT INTO "user" (id, name) VALUES (:id, :name)
conn.execute(user.insert(),{'id':7,'name':'seven'})
conn.close()
 
# sql = user.insert().values(id=123, name='wu')
# conn.execute(sql)
# conn.close()
 
# sql = user.delete().where(user.c.id > 1)
 
# sql = user.update().values(fullname=user.c.name)
# sql = user.update().where(user.c.name == 'jack').values(name='ed')
 
# sql = select([user, ])
# sql = select([user.c.id, ])
# sql = select([user.c.name, color.c.name]).where(user.c.id==color.c.id)
# sql = select([user.c.name]).order_by(user.c.name)
# sql = select([user]).group_by(user.c.name)
 
# result = conn.execute(sql)
# print result.fetchall()
# conn.close()

一个简单的完整例子

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String
from  sqlalchemy.orm import sessionmaker
 
Base = declarative_base() #生成一个SqlORM 基类
 
 
engine = create_engine("mysql+mysqldb://root@localhost:3306/test",echo=False)
 
 
class Host(Base):
    __tablename__ = 'hosts'
    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)
 
Base.metadata.create_all(engine) #创建所有表结构
 
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()
    #h1 = Host(hostname='localhost',ip_addr='127.0.0.1')
    #h2 = Host(hostname='ubuntu',ip_addr='192.168.2.243',port=20000)
    #h3 = Host(hostname='ubuntu2',ip_addr='192.168.2.244',port=20000)
    #session.add(h3)
    #session.add_all( [h1,h2])
    #h2.hostname = 'ubuntu_test' #只要没提交,此时修改也没问题
    #session.rollback()
    #session.commit() #提交
    res = session.query(Host).filter(Host.hostname.in_(['ubuntu2','localhost'])).all()
    print(res)

更多内容详见：

http://www.jianshu.com/p/e6bba189fcbd

http://docs.sqlalchemy.org/en/latest/core/expression_api.html

注：SQLAlchemy无法修改表结构，如果需要可以使用SQLAlchemy开发者开源的另外一个软件Alembic来完成。

步骤三：

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。

#!/usr/bin/env python
# -*- coding:utf-8 -*-
  
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
  
engine = create_engine("mysql+mysqldb://root:123@127.0.0.1:3306/s11", max_overflow=5)
  
Base = declarative_base()
  
  
class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String(50))
  
# 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
# Base.metadata.create_all(engine)
  
Session = sessionmaker(bind=engine)
session = Session()
  
  
# ########## 增 ##########
# u = User(id=2, name='sb')
# session.add(u)
# session.add_all([
#     User(id=3, name='sb'),
#     User(id=4, name='sb')
# ])
# session.commit()
  
# ########## 删除 ##########
# session.query(User).filter(User.id > 2).delete()
# session.commit()
  
# ########## 修改 ##########
# session.query(User).filter(User.id > 2).update({'cluster_id' : 0})
# session.commit()
# ########## 查 ##########
# ret = session.query(User).filter_by(name='sb').first()
  
# ret = session.query(User).filter_by(name='sb').all()
# print ret
  
# ret = session.query(User).filter(User.name.in_(['sb','bb'])).all()
# print ret
  
# ret = session.query(User.name.label('name_label')).all()
# print ret,type(ret)
  
# ret = session.query(User).order_by(User.id).all()
# print ret
  
# ret = session.query(User).order_by(User.id)[1:3]
# print ret
# session.commit()

外键关联

A one to many relationship places a foreign key on the child table referencing the parent.relationship() is then specified on the parent, as referencing a collection of items represented by the child

from sqlalchemy import Table, Column, Integer, ForeignKey
from sqlalchemy.orm import relationship
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

<br>class Parent(Base):
    __tablename__ = 'parent'
    id = Column(Integer, primary_key=True)
    children = relationship("Child")
 
class Child(Base):
    __tablename__ = 'child'
    id = Column(Integer, primary_key=True)
    parent_id = Column(Integer, ForeignKey('parent.id'))

To establish a bidirectional relationship in one-to-many, where the “reverse” side is a many to one, specify an additional relationship() and connect the two using therelationship.back_populates parameter:

class Parent(Base):
    __tablename__ = 'parent'
    id = Column(Integer, primary_key=True)
    children = relationship("Child", back_populates="parent")
 
class Child(Base):
    __tablename__ = 'child'
    id = Column(Integer, primary_key=True)
    parent_id = Column(Integer, ForeignKey('parent.id'))
    parent = relationship("Parent", back_populates="children")

Child will get a parent attribute with many-to-one semantics.

Alternatively, the backref option may be used on a single relationship() instead of usingback_populates:

class Parent(Base):
    __tablename__ = 'parent'
    id = Column(Integer, primary_key=True)
    children = relationship("Child", backref="parent")

原生sql join查询

几个Join的区别 http://stackoverflow.com/questions/38549/difference-between-inner-and-outer-joins

INNER JOIN: Returns all rows when there is at least one match in BOTH tables
LEFT JOIN: Return all rows from the left table, and the matched rows from the right table
RIGHT JOIN: Return all rows from the right table, and the matched rows from the left table

select host.id,hostname,ip_addr,port,host_group.name from host right join host_group on host.id = host_group.host_id

in SQLAchemy

session.query(Host).join(Host.host_groups).filter(HostGroup.name=='t1').group_by("Host").all()

group by 查询

select name,count(host.id) as NumberOfHosts from host right join host_group on host.id= host_group.host_id group by name;

in SQLAchemy

from sqlalchemy import func
session.query(HostGroup, func.count(HostGroup.name )).group_by(HostGroup.name).all()

#another example
session.query(func.count(User.name), User.name).group_by(User.name).all() SELECT count(users.name) AS count_1, users.name AS users_name
FROM users GROUP BY users.name

堡垒机功能实现需求

业务需求:

兼顾业务安全目标与用户体验，堡垒机部署后，不应使用户访问业务系统的访问变的复杂，否则工作将很难推进，因为没人喜欢改变现状，尤其是改变后生活变得更艰难
保证堡垒机稳定安全运行，没有100%的把握，不要上线任何新系统，即使有100%把握，也要做好最坏的打算，想好故障预案

功能需求：

所有的用户操作日志要保留在数据库中
每个用户登录堡垒机后，只需要选择具体要访问的设置，就连接上了，不需要再输入目标机器的访问密码
允许用户对不同的目标设备有不同的访问权限，例:

对10.0.2.34 有mysql 用户的权限
对192.168.3.22 有root用户的权限
对172.33.24.55 没任何权限

分组管理，即可以对设置进行分组，允许用户访问某组机器，但对组里的不同机器依然有不同的访问权限

设计表结构:

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#_*_coding:utf-8_*_
__author__ = 'Alex Li'
 
from sqlalchemy import create_engine,Table
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String,ForeignKey,UniqueConstraint
from sqlalchemy.orm import relationship
from  sqlalchemy.orm import sessionmaker
from sqlalchemy import or_,and_
from sqlalchemy import func
from sqlalchemy_utils import ChoiceType,PasswordType
 
Base = declarative_base() #生成一个SqlORM 基类
 
 
engine = create_engine("mysql+mysqldb://root@localhost:3306/test",echo=False)
 
 
BindHost2Group = Table('bindhost_2_group',Base.metadata,
    Column('bindhost_id',ForeignKey('bind_host.id'),primary_key=True),
    Column('group_id',ForeignKey('group.id'),primary_key=True),
)
 
BindHost2UserProfile = Table('bindhost_2_userprofile',Base.metadata,
    Column('bindhost_id',ForeignKey('bind_host.id'),primary_key=True),
    Column('uerprofile_id',ForeignKey('user_profile.id'),primary_key=True),
)
 
Group2UserProfile = Table('group_2_userprofile',Base.metadata,
    Column('userprofile_id',ForeignKey('user_profile.id'),primary_key=True),
    Column('group_id',ForeignKey('group.id'),primary_key=True),
)
 
 
class UserProfile(Base):
    __tablename__ = 'user_profile'
    id = Column(Integer,primary_key=True,autoincrement=True)
    username = Column(String(32),unique=True,nullable=False)
    password = Column(String(128),unique=True,nullable=False)
    groups = relationship('Group',secondary=Group2UserProfile)
    bind_hosts = relationship('BindHost',secondary=BindHost2UserProfile)
 
    def __repr__(self):
        return "<UserProfile(id='%s',username='%s')>" % (self.id,self.username)
 
class RemoteUser(Base):
    __tablename__ = 'remote_user'
    AuthTypes = [
        (u'ssh-passwd',u'SSH/Password'),
        (u'ssh-key',u'SSH/KEY'),
    ]
    id = Column(Integer,primary_key=True,autoincrement=True)
    auth_type = Column(ChoiceType(AuthTypes))
    username = Column(String(64),nullable=False)
    password = Column(String(255))
 
    __table_args__ = (UniqueConstraint('auth_type', 'username','password', name='_user_passwd_uc'),)
 
    def __repr__(self):
        return "<RemoteUser(id='%s',auth_type='%s',user='%s')>" % (self.id,self.auth_type,self.username)
 
 
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)
    bind_hosts = relationship("BindHost")
    def __repr__(self):
        return "<Host(id='%s',hostname='%s')>" % (self.id,self.hostname)
 
class Group(Base):
    __tablename__  = 'group'
    id = Column(Integer,primary_key=True,autoincrement=True)
    name = Column(String(64),nullable=False,unique=True)
    bind_hosts = relationship("BindHost",secondary=BindHost2Group, back_populates='groups' )
    user_profiles = relationship("UserProfile",secondary=Group2UserProfile )
 
    def __repr__(self):
        return "<HostGroup(id='%s',name='%s')>" % (self.id,self.name)
 
 
class BindHost(Base):
    '''Bind host with different remote user,
       eg. 192.168.1.1 mysql passAbc123
       eg. 10.5.1.6    mysql pass532Dr!
       eg. 10.5.1.8    mysql pass532Dr!
       eg. 192.168.1.1 root
    '''
    __tablename__ = 'bind_host'
    id = Column(Integer,primary_key=True,autoincrement=True)
    host_id = Column(Integer,ForeignKey('host.id'))
    remoteuser_id = Column(Integer,ForeignKey('remote_user.id'))
    host = relationship("Host")
    remoteuser = relationship("RemoteUser")
    groups = relationship("Group",secondary=BindHost2Group,back_populates='bind_hosts')
    user_profiles = relationship("UserProfile",secondary=BindHost2UserProfile)
 
    __table_args__ = (UniqueConstraint('host_id', 'remoteuser_id', name='_bindhost_and_user_uc'),)
 
    def __repr__(self):
        return "<BindHost(id='%s',name='%s',user='%s')>" % (self.id,
                                                           self.host.hostname,
                                                           self.remoteuser.username
                                                                      )
 
 
Base.metadata.create_all(engine) #创建所有表结构
 
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()
    #h1 = session.query(Host).filter(Host.hostname=='ubuntu4').first()
    #hg1 = session.query(HostGroup).filter(HostGroup.name=='t2').first()
 
    #h2 = Host(hostname='ubuntu4',ip_addr='192.168.1.21')
    #h3 = Host(hostname='ubuntu5',ip_addr='192.168.1.24',port=20000)
    #hg= HostGroup(name='TestServers3',host_id=h3.id)
    #hg2= HostGroup(name='TestServers2',host_id=h2.id)
    #hg3= HostGroup(name='TestServers3')
    #hg4= HostGroup(name='TestServers4')
    #session.add_all([hg3,hg4])
    #h2.host_groups = [HostGroup(name="t1"),HostGroup(name="t2")]
    #h3.host_groups = [HostGroup(name="t2")]
    #h1.host_groups.append(HostGroup(name="t3") )
    #print(h1.host_groups)
    #print("hg1:",hg1.host.hostname)
    #join_res = session.query(Host).join(Host.host_groups).filter(HostGroup.name=='t1').group_by("Host").all()
    #print('join select:',join_res)
    #group_by_res = session.query(HostGroup, func.count(HostGroup.name )).group_by(HostGroup.name).all()
    #print("-------------group by res-----")
 
    '''
    h1=Host(hostname='h1',ip_addr='1.1.1.1')
    h2=Host(hostname='h2',ip_addr='1.1.1.2')
    h3=Host(hostname='h3',ip_addr='1.1.1.3')
    r1=RemoteUser(auth_type=u'ssh-passwd',username='alex',password='abc123')
    r2=RemoteUser(auth_type=u'ssh-key',username='alex')
 
    g1 = Group(name='g1')
    g2 = Group(name='g2')
    g3 = Group(name='g3')
    session.add_all([h1,h2,h3,r1,r2])
    session.add_all([g1,g2,g3])
 
 
 
    b1 = BindHost(host_id=1,remoteuser_id=1)
    b2 = BindHost(host_id=1,remoteuser_id=2)
    b3 = BindHost(host_id=2,remoteuser_id=2)
    b4 = BindHost(host_id=3,remoteuser_id=2)
    session.add_all((b1,b2,b3,b4))
     
    all_groups = session.query(Group).filter().all() #first()
    all_bindhosts = session.query(BindHost).filter().all()
 
    #h1 = session.query(BindHost).filter(BindHost.host_id==1).first()
    #h1.groups.append(all_groups[1])
    #print("h1:",h1)
    #print("----------->",all_groups.name,all_groups.bind_hosts)
    u1 = session.query(UserProfile).filter(UserProfile.id==1).first()
    print('--user:',u1.bind_hosts)
    print('--user:',u1.groups[0].bind_hosts)
    #u1.groups = [all_groups[1] ]
    #u1.bind_hosts.append(all_bindhosts[1])
    #u1 = UserProfile(username='alex',password='123')
    #u2 = UserProfile(username='rain',password='abc!23')
    #session.add_all([u1,u2])
    #b1 = BindHost()
    session.commit()
    #print(h2.host_groups)
    '''

posted @ 2016-03-31 23:30 ~暴风~ 阅读(306) 评论(0) 编辑收藏举报

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Python学习笔记day11

SqlAlchemy ORM

外键关联

堡垒机功能实现需求

业务需求:

功能需求：

设计表结构:

公告

SqlAlchemy ORM　　