python操作三大主流数据库(3)python操作mysql③python操作mysql的orm工具sqlaichemy安装配置和使用

python操作mysql③python操作mysql的orm工具sqlaichemy安装配置和使用

手册地址：
http://docs.sqlalchemy.org/en/rel_1_1/orm/index.html

安装
D:\software\source_tar>pip install SQLALchemy

检测是否安装成功
D:\software\source_tar>python
Python 3.5.2 (v3.5.2:4def2a2901a5, Jun 25 2016, 22:18:55) [MSC v.1900 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import sqlalchemy


mysql的orm库SQLALchemy的操作

#coding:utf-8

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, DateTime, Boolean
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker


'''
    id int primary key auto_increment,
    title varchar(200) not null,
    content varchar(2000) not null,
    tpes varchar(10) not null,
    image varchar(300) null,
    author varchar(20) null,
    view_count int default 0,
    created_at datetime null,
    is_valid smallint default 1
'''
# 创建对象的基类
Base = declarative_base()
# 初始化数据库连接，注意要接上charset=utf8否则中文无法支持
engine = create_engine("mysql://root:@localhost/news?charset=utf8")
# 创建DBSession类型
DBSession = sessionmaker(bind=engine)

# 定义News对象
class News(Base):
    __tablename__ = 'news'
    id = Column(Integer, primary_key=True)
    title = Column(String(200), nullable=False)
    content = Column(String(2000), nullable=False)
    types = Column(String(10), nullable=False)
    image = Column(String(300),)
    author = Column(String(20),)
    view_count = Column(Integer)
    created_at = Column(DateTime)
    is_valid = Column(Boolean)

'''
# 简单测试
# 如果表不存在就创建表
Base.metadata.create_all(engine)

# 创建session对象:
session = DBSession()
# 创建新User对象，新增一条测试数据
news01 = News(title='标题1', content = 'content01', types = 'baidu', 
    image = '/static/img/01.jpg', author = 'jack', view_count = 3)
# 添加到session:
session.add(news01)
# 提交即保存到数据库:
session.commit()
# 关闭session:
session.close()
'''

# orm的测试类
class OrmTest(object):
    # 初始化创建session
    def __init__(self):
        self.session = DBSession()

    # 添加数据
    def add_one(self):
        new_obj = News(
            title = '标题20180202',
            content = '内容20180202',
            types = '百家'
            )
        self.session.add(new_obj)
        self.session.commit()
        return new_obj

    # 添加多条数据
    def add_more(self):
        add_list = []
        for i in range(10):
            new_obj = News(title='标题%s'%str(i),content='内容%s'%str(i),types='百家%s'%str(i))
            self.session.add(new_obj)
            add_list.append(new_obj)
        self.session.commit()
        return add_list

    # 删除数据
    def delete_data(self):
        data = self.session.query(News).get(51)
        self.session.delete(data)
        self.session.commit()

    # 修改单条数据
    def update_one(self, _id):
        obj = self.session.query(News).get(_id)
        if obj:
            obj.is_valid = 0
            self.session.add(obj)
            self.session.commit()
            return True

        return False


    # 修改多条数据
    def update_data(self):
        # filter_by的使用方法
        # data_list = self.session.query(News).filter_by(is_valid = 0)

        # filter的使用方法
        data_list = self.session.query(News).filter(News.id > 45)
        for data in data_list:
            print(data.title)
            data.is_valid = 1
            self.session.add(data)
        self.session.commit()

    # 获取一条数据
    def get_one(self):
        return self.session.query(News).get(1)

    # 获取多条数据
    def get_more(self):
        return self.session.query(News).filter_by(is_valid = 1)


def main():
    obj = OrmTest()
    # rst = obj.add_one()
    # print('id:%s, title:%s,content:%s,types = %s' % (rst.id,rst.title,rst.content,rst.types))

    # 添加多条数据
    # rst = obj.add_more()
    # for _new in rst:
    #     print('id:{0},title{1},content:{2}'.format(_new.id,_new.title,_new.content))

    # 测试删除
    # obj.delete_data()

    # 修改单条数据
    # print(obj.update_one(50))

    # 修改多条数据
    obj.update_data()

    # 测试获取一条数据的函数
    # rst = obj.get_one()
    # print(rst.title)

    # 获取多条数据
    # rst = obj.get_more()
    # for _news in rst:
    #     print('news id: %s, title:%s, content:%s' % (_news.id,_news.title,_news.content))


if __name__ == "__main__":
    main()