Upload app/core/db.py

app/core/db.py

@@ -0,0 +1,69 @@
+"""Async SQLAlchemy engine, session factory, and FastAPI dependency.
+
+Driver-agnostic: works with both aiosqlite (dev) and asyncpg (prod).
+"""
+
+from __future__ import annotations
+
+from collections.abc import AsyncGenerator
+from typing import Any
+
+from sqlalchemy.ext.asyncio import (
+    AsyncEngine,
+    AsyncSession,
+    async_sessionmaker,
+    create_async_engine,
+)
+from sqlalchemy.orm import DeclarativeBase
+
+from app.core.config import get_settings
+
+
+class Base(DeclarativeBase):
+    """Declarative base for all ORM models.
+
+    Re-exported here so Alembic env.py can import it from a single location.
+    """
+
+
+# === Engine & Session Factory ===
+
+_settings = get_settings()
+
+# SQLite needs check_same_thread=False even for async — handled by aiosqlite.
+# echo=False in production; controlled by env if needed later.
+_engine_kwargs: dict[str, Any] = {"echo": False, "future": True}
+
+# For PostgreSQL asyncpg, pool sizing matters; for SQLite it's irrelevant.
+if not _settings.DATABASE_URL.startswith("sqlite"):
+    _engine_kwargs["pool_size"] = 5
+    _engine_kwargs["max_overflow"] = 10
+    _engine_kwargs["pool_pre_ping"] = True
+
+engine: AsyncEngine = create_async_engine(_settings.DATABASE_URL, **_engine_kwargs)
+
+AsyncSessionLocal: async_sessionmaker[AsyncSession] = async_sessionmaker(
+    bind=engine,
+    expire_on_commit=False,
+    class_=AsyncSession,
+    autoflush=False,
+)
+
+
+# === Dependency ===
+
+
+async def get_db() -> AsyncGenerator[AsyncSession, None]:
+    """FastAPI dependency that yields an AsyncSession and ensures cleanup."""
+    async with AsyncSessionLocal() as session:
+        try:
+            yield session
+        except Exception:
+            await session.rollback()
+            raise
+        # No explicit close needed — async context manager handles it.
+
+
+async def dispose_engine() -> None:
+    """Dispose of the engine on application shutdown."""
+    await engine.dispose()