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  • Python使用Alembic框架进行数据库版本管理

      安装

    pip install alembic
    

      初始化

    alembic init alembic
    

      修改配置alembic.ini

    sqlalchemy.url = driver://user:pass@localhost/dbname
    

      修改env.py

    import sys
    from logging.config import fileConfig
    from os.path import abspath, dirname
    
    from alembic import context
    from sqlalchemy import engine_from_config
    from sqlalchemy import pool
    
    sys.path.append(dirname(dirname(abspath(__file__))))
    from models.models import Base
    
    # this is the Alembic Config object, which provides
    # access to the values within the .ini file in use.
    config = context.config
    
    # Interpret the config file for Python logging.
    # This line sets up loggers basically.
    fileConfig(config.config_file_name)
    
    # add your model's MetaData object here
    # for 'autogenerate' support
    # from myapp import mymodel
    # target_metadata = mymodel.Base.metadata
    target_metadata = Base.metadata
    
    
    # other values from the config, defined by the needs of env.py,
    # can be acquired:
    # my_important_option = config.get_main_option("my_important_option")
    # ... etc.
    
    
    def run_migrations_offline():
        """Run migrations in 'offline' mode.
    
        This configures the context with just a URL
        and not an Engine, though an Engine is acceptable
        here as well.  By skipping the Engine creation
        we don't even need a DBAPI to be available.
    
        Calls to context.execute() here emit the given string to the
        script output.
    
        """
        url = config.get_main_option("sqlalchemy.url")
        context.configure(
            url=url,
            target_metadata=target_metadata,
            literal_binds=True,
            dialect_opts={"paramstyle": "named"},
        )
    
        with context.begin_transaction():
            context.run_migrations()
    
    
    def run_migrations_online():
        """Run migrations in 'online' mode.
    
        In this scenario we need to create an Engine
        and associate a connection with the context.
    
        """
        connectable = engine_from_config(
            config.get_section(config.config_ini_section),
            prefix="sqlalchemy.",
            poolclass=pool.NullPool,
        )
    
        with connectable.connect() as connection:
            context.configure(
                connection=connection, target_metadata=target_metadata
            )
    
            with context.begin_transaction():
                context.run_migrations()
    
    
    if context.is_offline_mode():
        run_migrations_offline()
    else:
        run_migrations_online()

      创建第一个版本

    alembic revision --autogenerate -m "init"  
    

      修改模型

    alembic revision --autogenerate -m "update"
    

      升级

    alembic upgrade head  #每次要创建新的版本,需要执行数据库升级到新版本的命令,才能继续更新版本

      降级

    alembic downgrade 版本号
    

      

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  • 原文地址:https://www.cnblogs.com/john-xiong/p/13338290.html
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