sqlalchemy整理（三）

继续承接一二

之前的例子都是基于sqllite3的，下面的例子是针对mysql的

1.基于配置文件读取数据库配置，其实就是一个ConfigParser读取一个配置文件db.conf

代码：

import ConfigParser

#get the connect db conf 
def read_conf(db_type="mysql"):
    conf=ConfigParser.ConfigParser()
    conf.read("./db.conf")
    sec=db_type
    db_user=conf.get(sec,"db_user")
    db_password=conf.get(sec,"db_password")
    db_host=conf.get(sec,"db_host")
    db_port=conf.get(sec,"db_port")
    db_name=conf.get(sec,"db_name")
    return "{0}://{1}:{2}@{3}:{4}/{5}".format(db_type,db_user,db_password,db_host,db_port,db_name)

配置文件：

[mysql]
db_user=hello
db_password=hello
db_host=10.210.71.145
db_name=index_test
db_port=3306

2. 加入mapper映射到class ，并且加入session 控制

已经存在的table people，代码中没有创建直接使用了，

sql ，很早之前创建的了，对字段的设计太低级了，莫见笑

mysql> show create table people \G;
*************************** 1. row ***************************
       Table: people
Create Table: CREATE TABLE `people` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `zipcode` char(32) NOT NULL DEFAULT '',
  `address` varchar(128) NOT NULL DEFAULT '',
  `lastname` char(64) NOT NULL DEFAULT '',
  `firstname` char(64) NOT NULL DEFAULT '',
  `birthdate` char(10) NOT NULL DEFAULT '',
  PRIMARY KEY (`id`),
  KEY `zipcode` (`zipcode`,`firstname`,`lastname`)
) ENGINE=InnoDB AUTO_INCREMENT=21 DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

1.创建引擎
2.matadata和引擎关联
3.metadata和table关联，得到一个table的对象
4.类和table绑定
5.session和引擎关联
以上得到了session和table和类的关联关系建好了

接下来是对table的操作相关

import ConfigParser

#get the connect db conf 
def read_conf(db_type="mysql"):
    conf=ConfigParser.ConfigParser()
    conf.read("./db.conf")
    sec=db_type
    db_user=conf.get(sec,"db_user")
    db_password=conf.get(sec,"db_password")
    db_host=conf.get(sec,"db_host")
    db_port=conf.get(sec,"db_port")
    db_name=conf.get(sec,"db_name")
    return "{0}://{1}:{2}@{3}:{4}/{5}".format(db_type,db_user,db_password,db_host,db_port,db_name)


from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import  mapper,sessionmaker
from sqlalchemy import schema,types,select
from sqlalchemy import create_engine

#class  test one
class People(object):
    pass

#get db url
db_url=read_conf()
print db_url

#create engine
engine = create_engine(db_url)
engine.echo = False

metadata=schema.MetaData(engine)

# i have create a table before  so just auto load it 
people_table =schema.Table('people',metadata, autoload=True)

#make mapper
mapper(People, people_table)

#connect
connection = engine.connect()

#create session
#binf engine with session
Session=sessionmaker(bind=engine)
session=Session()

#query with filter
peoples=session.query(People).filter(People.id==2)
for people in peoples:
    print people.id,people.zipcode,people.address,people.lastname,people.firstname,people.birthdate
    people.lastname="hello world"
    session.flush()
    session.commit()
print "############"


#query without  any sql
peoples=session.query(People).filter()
for people in peoples:
    print people.id,people.zipcode,people.address,people.lastname,people.firstname,people.birthdate

#insert with mapper class
people=People()
people.zipcode="010"
people.address="hello world"
people.lastname="world hello"
people.firstname="hello  xluren"
people.birthdate="19900606"

# make insert ok,we need add flush commit 
session.add(people)
session.flush()
session.commit()

#query with filter
peoples=session.query(People).filter(People.id>2)
for people in peoples:
    print people.id,people.zipcode,people.address,people.lastna