Mysql实现自动升级

文章目录

一、mysql表设计
二、mysql orm生成
三、修改orm
四、mysql orm刷回数据库
五、参考

背景： 建立一个数据库mydb, 含有一个表employee, employee_single通过id外键关联，实现删除employee记录关联删除employee_single对应的记录。刷出orm，实现修改orm后可以自动将表修改部分刷回数据库。

一、mysql表设计

建库：

CREATE DATABASE mydb;

建表：employee 、employee_single

CREATE TABLE `employee` (`PID` int(11) unsigned NOT NULL AUTO_INCREMENT,`ID` varchar(64) DEFAULT NULL COMMENT 'this is employee id',`Name` varchar(64) NOT NULL DEFAULT '' COMMENT 'this is employee name',`UpdateTime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,`Extend0` varchar(100) DEFAULT NULL,PRIMARY KEY (`PID`),UNIQUE KEY `id_idx` (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=800 DEFAULT CHARSET=utf8;

CREATE TABLE `employee_single` (`PID` int(11) unsigned NOT NULL AUTO_INCREMENT,`ID` varchar(64) NOT NULL DEFAULT '' COMMENT 'this is employee id',`addr` varchar(64) NOT NULL DEFAULT '' COMMENT 'this is employee addr',`age` int(11) NOT NULL DEFAULT '0' COMMENT 'this is employee age',PRIMARY KEY (`PID`),UNIQUE KEY `id_idx` (`ID`),CONSTRAINT `fk_employee_single` FOREIGN KEY (`ID`) REFERENCES `employee` (`ID`) ON DELETE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=2189 DEFAULT CHARSET=utf8;

二、mysql orm生成

依赖安装：安装依赖库sqlacodegen、SQLAlchemy

pip install sqlacodegen

生成orm:

sqlacodegen --outfile employee_object.py mysql+pymysql://root:yourpassword@localhost/mydb

三、修改orm

在生成的orm文件employee_object.py中添加字段，如在employee_single表添加Phone, 直接修改orm那么原来的class EmployeeSingle变成如下：

class EmployeeSingle(Base):__tablename__ = 'employee_single'PID = Column(INTEGER(11), primary_key=True)ID = Column(ForeignKey('employee.ID', ondelete='CASCADE'), nullable=False, unique=True, server_default=text("''"), comment='this is employee id')addr = Column(String(64), nullable=False, server_default=text("''"), comment='this is employee addr')age = Column(INTEGER(11), nullable=False, server_default=text("'0'"), comment='this is employee age')Phone = Column(String(32), nullable=False, server_default=text("'0'"), comment='this is employee phone')employee = relationship('Employee')

你也可以直接修改数据库，然后用第二步方法生成新的orm

四、mysql orm刷回数据库

安装依赖：

pip install alembic

在orm employee_object.py同级目录创建一个文件，employee_orm_update.py用于将orm修改刷回数据库。
代码如下:

#!encoding=utf-8
import os
import re
import shutil
import pymysql
from os.path import dirname, abspathhost_name = "127.0.0.1"
password = "yourpassword"
db = "mydb"
port = 3306class EmployeeUpgrade:def __init__(self):self.connect = pymysql.connect(host=host_name, port=port, user='root', passwd=password, local_infile=True,charset='utf8')self.cur = self.connect.cursor()self.delete_config()self.cur.execute("Create Database If Not Exists {} Character Set UTF8;".format(db))self.cur.execute("use {};".format(db))self.cur.execute("drop table if exists alembic_version;")self.change_config()@classmethoddef change_config(cls):os.system("alembic init alembic")cls.config_util(os.path.join(dirname(abspath(__file__)), "alembic.ini"), 'sqlalchemy.url =','sqlalchemy.url = mysql+pymysql://root:{0}@{1}:{2}/{3}'.format(password, host_name, port, db))cls.config_util(os.path.join(dirname(abspath(__file__)), 'alembic', 'env.py'),'target_metadata = None','from employee_object import Base\n''target_metadata = Base.metadata')@classmethoddef config_util(cls, config_path, s_from, s_to):config_str = ''with open(config_path, 'r', encoding='utf-8') as f:str_list = f.readlines()for s in str_list:if len(re.findall("^{0}".format(s_from), s)) > 0:s = s_to + '\n'config_str += swith open(config_path, 'w', encoding='utf-8') as f:f.write(config_str)@staticmethoddef delete_config():try:if os.path.exists(os.path.join(dirname(abspath(__file__)), 'alembic')):shutil.rmtree(os.path.join(dirname(abspath(__file__)), 'alembic'))os.remove(os.path.join(dirname(abspath(__file__)), 'alembic.ini'))except Exception as ex:print(str(ex))def up_to_date(self):os.system("alembic revision --autogenerate -m 'init'")os.system("alembic upgrade head")self.delete_config()if __name__ == '__main__':EmployeeUpgrade().up_to_date()

核心代码：
执行：
alembic init alembic
修改：
alembic.ini
env.py
执行
alembic revision --autogenerate -m 'init'
alembic upgrade head

五、参考

sqlacodegen: 链接
SQLAlchemy 链接
Alembic 链接