既然说了flask-sqlalchemy，怎么着也得说说flask-migration了，毕竟平时数据库变更对于非DBA来说还是挺困难的呢。。。那么，接下来请点击全文吧～
安装命令pip install flask-migrate
注意:warning:相关的表结构示例， 请点击该链接。
一、配置flask-migrate# 文件名 hello.py from flask_migrate import Migrate,MigrateCommand migrate = Migrate(app,db) manager.add_command('db',MigrateCommand)
二、使用init命令创建迁移仓库python hello.py db init Creating directory /Users/domain/mycoding/web/migrations ... done Creating directory /Users/domain/mycoding/web/migrations/versions ... done Generating /Users/domain/mycoding/web/migrations/alembic.ini ... done Generating /Users/domain/mycoding/web/migrations/env.py ... done Generating /Users/domain/mycoding/web/migrations/env.pyc ... done Generating /Users/domain/mycoding/web/migrations/README ... done Generating /Users/domain/mycoding/web/migrations/script.py.mako ... done Please edit configuration/connection/logging settings in '/Users/domain/mycoding/web/migrations/alembic.ini' before proceeding. teardown request http://localhost/
三、使用migrate命令创建迁移脚本 python hello.py db migrate -m "initial migrateion" INFO [alembic.runtime.migration] Context impl mysqlImpl. INFO [alembic.runtime.migration] Will assume non-transactional DDL. INFO [alembic.autogenerate.compare] Detected added table 'roles' INFO [alembic.autogenerate.compare] Detected added table 'users' INFO [alembic.autogenerate.compare] Detected added index 'ix_users_username' on '['username']' Generating /Users/domain/mycoding/web/migrations/versions/e89e2c8b3174_initial_migrateion.py ... done该步骤生成的迁移脚本，可在./migrations/versions/的文件夹下面查看，迁移脚本中的upgrade()和downgrade()函数，它们的作用分别是：
upgrade()：将迁移中的改动应用到数据库中。
downgrade()：将迁移中的改动从数据库中删除，即具有回滚到某个迁移点的功能。
该步骤还会在数据库中生成 alembic_version 表，该表作为flask-migrateion的迁移记录表。
四、使用upgrade命令将迁移中的改动应用到数据库中 python hello.py db upgrade INFO [alembic.runtime.migration] Context impl MySQLImpl. INFO [alembic.runtime.migration] Will assume non-transactional DDL. INFO [alembic.runtime.migration] Running upgrade -> e89e2c8b3174, initial migrateion五、使用downgrade命令回滚迁移中的数据库改动
# 首先在之前flaks-sqlalchemy表结构的user表里面添加一个email字段 # class User(db.Model): # ... # email = db.Column(db.String(32), nullable=False, server_default='') # ... # 使用python hello.py db migrate -m 'add email column to user table'命令生成迁移脚本 python hello.py db migrate -m 'add email column to user table' INFO [alembic.runtime.migration] Context impl MySQLImpl. INFO [alembic.runtime.migration] Will assume non-transactional DDL. INFO [alembic.autogenerate.compare] Detected added column 'users.email' Generating /Users/domain/mycoding/web/migrations/versions/c779bf595f79_add_email_column_to_user_table.py ... done # 使用python hello.py db upgrade将迁移脚本中的改动应用到 python hello.py db upgrade INFO [alembic.runtime.migration] Context impl MySQLImpl. INFO [alembic.runtime.migration] Will assume non-transactional DDL. INFO [alembic.runtime.migration] Running upgrade d303dfaaefba -> c779bf595f79, add email column to user table # 此时发现并不想做这个变更，想要回滚到上一个版本咋办呢，来来来，我教你个大招 python hello.py db downgrade d303dfaaefba INFO [alembic.runtime.migration] Context impl MySQLImpl. INFO [alembic.runtime.migration] Will assume non-transactional DDL. INFO [alembic.runtime.migration] Running downgrade c779bf595f79 -> d303dfaaefba, add email column to user table # d303dfaaefba为上一个版本号，可以从数据库中的alembic_version表中查询到，也可以从上面python hello.py db upgrade的最后一个INFO信息中查看到，当然也可以用./migrations/versions/的文件夹下面查看到，总之看到版本号的地方很多，就看你是否是个有心人了～至此，Flask-Migrateion的用法就整理完毕了，当然Flask-Migration还有很多用法，但是上面这些是最常用的用法，更相信的用法请参考 Flask-Migrationg官方文档 。
当然也请小伙伴们放心，在整个flask-migration迁移过程中，你的数据也会跟着迁移的，所以完全不用担心哈～
本文整理参考文档：《Flask web开发》