Initial commit: InternalAuditInterprise

backend/app/db.py

@@ -0,0 +1,40 @@
+"""数据库引擎与会话管理。"""
+
+from __future__ import annotations
+
+from collections.abc import Iterator
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import DeclarativeBase, Session, sessionmaker
+
+from app.config import get_settings
+
+
+class Base(DeclarativeBase):
+    """所有 ORM 模型的基类。"""
+
+
+_engine = None
+_SessionLocal: sessionmaker[Session] | None = None
+
+
+def get_engine():
+    global _engine
+    if _engine is None:
+        settings = get_settings()
+        _engine = create_engine(settings.database_url, pool_pre_ping=True, future=True)
+    return _engine
+
+
+def get_sessionmaker() -> sessionmaker[Session]:
+    global _SessionLocal
+    if _SessionLocal is None:
+        _SessionLocal = sessionmaker(bind=get_engine(), expire_on_commit=False)
+    return _SessionLocal
+
+
+def get_session() -> Iterator[Session]:
+    """FastAPI 依赖注入用的会话生成器。"""
+    sm = get_sessionmaker()
+    with sm() as session:
+        yield session