73 lines
1.9 KiB
Python
73 lines
1.9 KiB
Python
 
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"""Async SQLAlchemy engine/session management (SPEC §2 ``app/db.py``)."""
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from __future__ import annotations
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from collections.abc import AsyncIterator
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from contextlib import asynccontextmanager
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from sqlalchemy.ext.asyncio import (
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AsyncEngine,
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AsyncSession,
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async_sessionmaker,
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create_async_engine,
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)
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from sqlalchemy.orm import DeclarativeBase
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from app.config import get_settings
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_engine: AsyncEngine | None = None
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_sessionmaker: async_sessionmaker[AsyncSession] | None = None
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class Base(DeclarativeBase):
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"""Declarative base for all ORM models."""
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def get_engine() -> AsyncEngine:
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"""Return (creating on first use) the process-wide async engine."""
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global _engine
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if _engine is None:
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_engine = create_async_engine(
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get_settings().database_url,
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pool_pre_ping=True,
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future=True,
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)
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return _engine
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def get_sessionmaker() -> async_sessionmaker[AsyncSession]:
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"""Return the process-wide session factory."""
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global _sessionmaker
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if _sessionmaker is None:
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_sessionmaker = async_sessionmaker(
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get_engine(), expire_on_commit=False, class_=AsyncSession
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)
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return _sessionmaker
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@asynccontextmanager
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async def session_scope() -> AsyncIterator[AsyncSession]:
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"""Transactional session context manager for workers and scripts."""
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async with get_sessionmaker()() 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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async def get_session() -> AsyncIterator[AsyncSession]:
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"""FastAPI dependency yielding a request-scoped session."""
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async with get_sessionmaker()() as session:
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yield session
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async def dispose_engine() -> None:
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"""Dispose the engine (used on app shutdown)."""
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global _engine, _sessionmaker
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if _engine is not None:
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await _engine.dispose()
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_engine = None
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_sessionmaker = None
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