python -- ORM

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我是靠谱客的博主爱听歌洋葱，这篇文章主要介绍python -- ORM，现在分享给大家，希望可以做个参考。

ORM – 对象关系映射，将纯SQL语句进行了抽象化处理，即数据库映射，python知名的ORM库SQLAlchemy和SQLObject

安装sqlalchemy

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pip install sqlalchemy

关于sqlalchemy的使用，下面举了一个简单的例子：

复制代码

# coding=utf-8
"""
@version: ??
@author: AA-ldc
@file: testDB.py
@time: 2017/3/20 9:24
@function：ORM--对象关系映射
"""
from sqlalchemy import exc, create_engine, orm
from contextlib import contextmanager
import ConfigParser
from data.User import Student
class SQLAlchemyManage(object):
def __init__(self, db_name):
try:
config = ConfigParser.ConfigParser()
config.readfp(open('config/config.ini'), "rb")
dsn = 'mssql+pymssql://%s:%s@%s/%s' % (config.get('mssql', 'user'), config.get('mssql', 'pwd'),
config.get('mssql', 'host'), db_name)
eng = create_engine(dsn, echo=False)
except ImportError:
raise RuntimeError()
try:
eng.connect()
except exc.OperationalError:
raise RuntimeError()
print ('Connect to database <%s> success.' % db_name)
self.eng = eng
def GetSession(self):
# 定义会话类型
SessionType = orm.scoped_session(orm.sessionmaker(bind=self.eng, expire_on_commit=False))
return SessionType
# 定义上下文函数，使能够自动进行事务处理，
# 定义上下文件函数的方法就是加上contextmanager装饰器
# 执行逻辑：在函数开始时建立数据库会话，此时会自动建立一个数据库事务；当发生异常时回滚（rollback）事务，当
# 退出时关闭(close)连接
@contextmanager
def session_scope(self):
session = self.GetSession()
try:
yield session
session.commit()
except:
session.rollback()
raise RuntimeError()
finally:
session.close()
# 查询
def Query(self):
with self.session_scope() as session:
users = session.query(Student).all()
return users
def main():
orm = SQLAlchemyManage("test")
users = orm.Query()
for user in users:
print user.FIRST_NAME, user.AGE
if __name__ == '__main__':
main()

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# coding=utf-8
"""
@version: ??
@author: AA-ldc
@file: testDB.py
@time: 2017/3/20 9:24
@function：ORM--对象关系映射
"""
from sqlalchemy import exc, create_engine, orm
from contextlib import contextmanager
import ConfigParser
from data.User import Student
class SQLAlchemyManage(object):
def __init__(self, db_name):
try:
config = ConfigParser.ConfigParser()
config.readfp(open('config/config.ini'), "rb")
dsn = 'mssql+pymssql://%s:%s@%s/%s' % (config.get('mssql', 'user'), config.get('mssql', 'pwd'),
config.get('mssql', 'host'), db_name)
eng = create_engine(dsn, echo=False)
except ImportError:
raise RuntimeError()
try:
eng.connect()
except exc.OperationalError:
raise RuntimeError()
print ('Connect to database <%s> success.' % db_name)
self.eng = eng
def GetSession(self):
# 定义会话类型
SessionType = orm.scoped_session(orm.sessionmaker(bind=self.eng, expire_on_commit=False))
return SessionType
# 定义上下文函数，使能够自动进行事务处理，
# 定义上下文件函数的方法就是加上contextmanager装饰器
# 执行逻辑：在函数开始时建立数据库会话，此时会自动建立一个数据库事务；当发生异常时回滚（rollback）事务，当
# 退出时关闭(close)连接
@contextmanager
def session_scope(self):
session = self.GetSession()
try:
yield session
session.commit()
except:
session.rollback()
raise RuntimeError()
finally:
session.close()
# 查询
def Query(self):
with self.session_scope() as session:
users = session.query(Student).all()
return users
def main():
orm = SQLAlchemyManage("test")
users = orm.Query()
for user in users:
print user.FIRST_NAME, user.AGE
if __name__ == '__main__':
main()

另外创建一个数据类 Student

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# coding=utf-8
from sqlalchemy import Column, String, Float, Integer
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()

class Student(Base):
__tablename__ = 'Student'
FIRST_NAME = Column(String(20), primary_key=True)
LAST_NAME = Column(String(20))
AGE = Column(Integer())
SEX = Column(String(1))
INCOME = Column(Float(precision=0.3))