feat: 开发采集、采集箱和商品编辑功能

server/db.py

@@ -0,0 +1,50 @@
+"""数据库引擎与会话工厂（SQLite 本地过渡 / PostgreSQL 生产）。"""
+from __future__ import annotations
+
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+from sqlalchemy.orm import DeclarativeBase
+
+from config import get_settings
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+_engine = None
+_session_factory = None
+
+
+def get_engine():
+    global _engine
+    if _engine is None:
+        settings = get_settings()
+        connect_args: dict = {}
+        # SQLite 需允许多线程/多协程访问同一文件
+        if settings.database_url.startswith("sqlite"):
+            connect_args["check_same_thread"] = False
+        _engine = create_async_engine(
+            settings.database_url,
+            echo=False,
+            future=True,
+            connect_args=connect_args,
+        )
+    return _engine
+
+
+def get_session_factory() -> async_sessionmaker[AsyncSession]:
+    global _session_factory
+    if _session_factory is None:
+        _session_factory = async_sessionmaker(
+            get_engine(),
+            class_=AsyncSession,
+            expire_on_commit=False,
+        )
+    return _session_factory
+
+
+async def get_db():
+    """FastAPI 依赖：请求级 AsyncSession。"""
+    factory = get_session_factory()
+    async with factory() as session:
+        yield session