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60 lines
1.8 KiB
60 lines
1.8 KiB
from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker, AsyncSession
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from sqlalchemy.orm import DeclarativeBase
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from sqlalchemy import text
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from config import settings
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class Base(DeclarativeBase):
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"""SQLAlchemy ORM 基类，所有数据库模型均继承此类。"""
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pass
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# 异步数据库引擎，连接池大小 20，最大溢出 40，启用连接健康检查
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async_engine = create_async_engine(
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settings.DATABASE_URL,
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pool_size=20,
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max_overflow=40,
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pool_pre_ping=True,
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pool_recycle=3600,
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echo=False,
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)
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# 异步数据库会话工厂，用于创建数据库会话实例
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AsyncSessionLocal = async_sessionmaker(
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async_engine,
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class_=AsyncSession,
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expire_on_commit=False,
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)
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async def init_db():
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"""初始化数据库：创建所有表并执行增量迁移。"""
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async with async_engine.begin() as conn:
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from models import Base as MBase
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await conn.run_sync(MBase.metadata.create_all)
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await _run_migrations()
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async def _run_migrations():
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"""执行数据库增量迁移，在已有表上安全添加新字段。"""
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async with async_engine.begin() as conn:
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await conn.execute(text(
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"ALTER TABLE flow_definitions ADD COLUMN IF NOT EXISTS published_version_id UUID REFERENCES flow_versions(id)"
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))
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await conn.execute(text(
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"ALTER TABLE flow_definitions ADD COLUMN IF NOT EXISTS draft_definition_json JSONB"
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))
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async def get_db():
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"""FastAPI 依赖注入函数，提供数据库会话，自动提交或回滚事务。"""
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async with AsyncSessionLocal() as session:
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try:
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yield session
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await session.commit()
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except Exception:
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await session.rollback()
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raise
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finally:
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await session.close()
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