feat: 修复代码审核报告问题

database.py

@@ -0,0 +1,39 @@
+"""数据库连接与初始化"""
+from pathlib import Path
+
+from sqlalchemy import create_engine, event
+from sqlalchemy.orm import sessionmaker, declarative_base
+
+from config import settings
+
+engine = create_engine(
+    f"sqlite:///{settings.database_path}",
+    connect_args={"check_same_thread": False},
+    echo=False,
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+Base = declarative_base()
+
+
+@event.listens_for(engine, "connect")
+def _set_sqlite_pragma(dbapi_conn, connection_record):
+    """启用 SQLite 外键约束"""
+    cursor = dbapi_conn.cursor()
+    cursor.execute("PRAGMA foreign_keys=ON")
+    cursor.close()
+
+
+def get_db():
+    """FastAPI 依赖注入用数据库会话"""
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+
+def init_db():
+    """创建所有数据表，并确保数据库目录存在"""
+    Path(settings.DATABASE_URL).parent.mkdir(parents=True, exist_ok=True)
+    Base.metadata.create_all(bind=engine)