python 数据库迁移

步骤

• 初始化

  alembic init alembic

• 配置初始数据库

  export DATABASE_URL='postgresql://postgres:password@localhost:5432/alembic_test1'

• 创建迁移脚本

  alembic revision --autogenerate -m "init"

• 设置 env.py

  from logging.config import fileConfig
  from sqlalchemy import engine_from_config
  from sqlalchemy import pool
  
  from alembic import context
  
  from open_webui.env import DATABASE_URL
  from open_webui.models import Base
  from open_webui.models import audios, auths, channels, chats, conference_table, config as config_model, courses, demos, document_stars, document_words, documents, feedbacks, file_chapters, files, folders, functions, groups, knowledge, memories, messages, models, ppt_tmpls, ppt_topics, ppts, prompts, references, tags, template, tools, translate_words, users
  print("Tables in metadata:", Base.metadata.tables.keys())
  
  # 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.
  if config.config_file_name is not None:
      fileConfig(config.config_file_name)
  
  config.set_main_option('sqlalchemy.url', DATABASE_URL)
  # 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() -> None:
      """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() -> None:
      """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()

• 手动升级

  alembic upgrade head

• 配置启动时执行升级

  def run_migrations():
      logger.info("Running migrations")
      try:
          logger.info("Loading alembic configuration, path: %s", BACKEND_DIR / "alembic.ini")
          alembic_cfg = Config(BACKEND_DIR / "alembic.ini")
  
          # 支持 pyinstaller
          if getattr(sys, 'frozen', False):
              alembic_cfg.set_main_option('script_location', os.path.join(getattr(sys, '_MEIPASS', '.'), 'alembic'))
          command.upgrade(alembic_cfg, "head")
      except Exception as e:
          logger.exception(f"Error running migrations: {e}")
  
  run_migrations()