python sqlalchemy-migrate 使用方法

1：下载相关模块

    pip install sqlalchemy

    pip install sqlalchemy-migrate

 

2:创建model （model.py),这里用来绑定数据库，创建sqlmodel，当然你也可以吧数据库设置和model分开。

#coding:utf-8

#made by dewei

from sqlalchemy import *

from sqlalchemy.ext.declarative import declarative_base  # db 基类

from sqlalchemy import Column, Integer, String, DateTime  # 相应的列

from sqlalchemy.orm import sessionmaker, relationship, backref, scoped_session  # 执行的相关方法

from sqlalchemy.dialects.mysql import LONGTEXT

 

import os

"""

设置数据库参数

"""

MYSQL_DB = 'sqlalchemy_migratetest'

MYSQL_USER = 'root'

MYSQL_PASSWD = 'dewei'

MYSQL_HOST = 'localhost'

MYSQL_POST = 3306

 

basedir = os.path.abspath(os.path.dirname(__file__))

SQLALCHEMY_DATABASE_URI = "mysql://%s:%s@%s:%s/%s?charset=utf8" % (MYSQL_USER, MYSQL_PASSWD, MYSQL_HOST, MYSQL_POST, MYSQL_DB)

SQLALCHEMY_MIGRATE_REPO = os.path.join(basedir, 'db_repository')  # 设置数据库迁移保存的文件夹，用来sqlalchemymigrate

 

db = create_engine(SQLALCHEMY_DATABASE_URI, echo=True)

 

Base = declarative_base()

db_session = scoped_session(sessionmaker(autocommit=False,

                                         autoflush=False,

                                         bind=db))

 

Base.query = db_session.query_property()

 

def isenit_db():

    Base.metadata.create_all(bind=db)

 

class User(Base):

    __tablename__ = "user"

    id = Column(Integer, primary_key=True)

    username = Column(String(100), unique=True, nullable=False)

    password = Column(String(200), nullable=False)

    email = Column(String(200), nullable=False)

 

    def __init__(self, username, password, email):

        self.username = username

        self.password = password

self.email = email

 

    def repr(self):

        return "" % (self.username, self.password)

 

3：生成 数据库并创建migrate迁移初始化 db_create.py

from model import SQLALCHEMY_DATABASE_URI, SQLALCHEMY_MIGRATE_REPO, db, Base

from migrate.versioning import api

import os.path

 

Base.metadata.create_all(bind=db)

 

if not os.path.exists(SQLALCHEMY_MIGRATE_REPO):

    api.create(SQLALCHEMY_MIGRATE_REPO, 'database repository')

    api.version_control(SQLALCHEMY_DATABASE_URI, SQLALCHEMY_MIGRATE_REPO)

else:

    api.version_control(SQLALCHEMY_DATABASE_URI, SQLALCHEMY_MIGRATE_REPO, api.version(SQLALCHEMY_MIGRATE_REPO))

 

当完成本py后 执行一次 仅一次就好， python db_create.py 这样数据库就创建好了 并且migrate也初始化完成，然后创建第四部，以后 添加数据库 就使用他就可以了

 

4 创建同步数据库py db_migrate.py

import imp

from migrate.versioning import api

from model import Base

from model import SQLALCHEMY_DATABASE_URI, SQLALCHEMY_MIGRATE_REPO

 

migration = SQLALCHEMY_MIGRATE_REPO + '/versions/d_migration.py' % (api.db_version(SQLALCHEMY_DATABASE_URI, SQLALCHEMY_MIGRATE_REPO) + 1)

tmp_module = imp.new_module('old_model')

old_model = api.create_model(SQLALCHEMY_DATABASE_URI, SQLALCHEMY_MIGRATE_REPO)

exec old_model in tmp_module.__dict__

script = api.make_update_script_for_model(SQLALCHEMY_DATABASE_URI, SQLALCHEMY_MIGRATE_REPO, tmp_module.meta, Base.metadata)

open(migration, 'wt').write(script)

api.upgrade(SQLALCHEMY_DATABASE_URI, SQLALCHEMY_MIGRATE_REPO)

print 'New migration saved as ' + migration

print 'Current database version: ' + str(api.db_version(SQLALCHEMY_DATABASE_URI, SQLALCHEMY_MIGRATE_REPO))

 

完成后 试着修改一次数据库 比如给user添加个新的字段 然后执行 python db_migrate.py 去sql里看看 已经添加完成了！