python sqlalchemy-migrate 使用方法

1：下載相關模塊

    pip install sqlalchemy

    pip install sqlalchemy-migrate

 

2:建立model （model.py),這裏用來綁定數據庫，建立sqlmodel，固然你也能夠吧數據庫設置和model分開。

#coding:utf-8

#made by dewei

from sqlalchemy import *

from sqlalchemy.ext.declarative import declarative_base  # db 基類

from sqlalchemy import Column, Integer, String, DateTime  # 相應的列

from sqlalchemy.orm import sessionmaker, relationship, backref, scoped_session  # 執行的相關方法

from sqlalchemy.dialects.mysql import LONGTEXT

 

import os

"""

設置數據庫參數

"""

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')  # 設置數據庫遷移保存的文件夾，用來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 數據庫並建立migrate遷移初始化 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))

 

當完成本py後 執行一次 僅一次就好， python db_create.py 這樣數據庫就建立好了 而且migrate也初始化完成，而後建立第四部，之後 添加數據庫 就使用他就能夠了

 

4 建立同步數據庫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))

 

完成後 試着修改一次數據庫 好比給user添加個新的字段 而後執行 python db_migrate.py 去sql裏看看 已經添加完成了！