提供基本前后端骨架

app/database.py

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+"""
+数据库连接与会话管理
+
+使用 SQLAlchemy 2.0 异步模式。
+"""
+
+import logging
+from collections.abc import AsyncGenerator
+from pathlib import Path
+
+from sqlalchemy.ext.asyncio import (
+    AsyncSession,
+    async_sessionmaker,
+    create_async_engine,
+)
+from sqlalchemy.orm import DeclarativeBase
+
+from app.core.config import settings
+
+logger = logging.getLogger(__name__)
+
+
+class Base(DeclarativeBase):
+    """SQLAlchemy 声明式基类"""
+    pass
+
+
+def _ensure_sqlite_dir() -> None:
+    """
+    确保 SQLite 数据库目录存在
+    
+    如果配置使用 SQLite，自动创建数据库文件所在的目录。
+    """
+    if settings.database_type != "sqlite":
+        return
+    
+    db_path = Path(settings.database_sqlite_path)
+    db_dir = db_path.parent
+    
+    if not db_dir.exists():
+        logger.info(f"创建数据库目录: {db_dir.absolute()}")
+        db_dir.mkdir(parents=True, exist_ok=True)
+
+
+# 确保 SQLite 目录存在
+_ensure_sqlite_dir()
+
+# 创建异步引擎
+engine = create_async_engine(
+    settings.database_url,
+    echo=settings.database_echo,
+    future=True,
+)
+
+# 创建异步会话工厂
+async_session_factory = async_sessionmaker(
+    engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+    autocommit=False,
+    autoflush=False,
+)
+
+
+async def get_db() -> AsyncGenerator[AsyncSession, None]:
+    """
+    获取数据库会话（依赖注入用）
+    
+    Yields:
+        异步数据库会话
+    """
+    async with async_session_factory() as session:
+        try:
+            yield session
+        finally:
+            await session.close()
+
+
+async def init_db() -> None:
+    """初始化数据库（创建所有表）"""
+    # 导入所有模型以确保它们被注册
+    from app.models import (  # noqa: F401
+        User,
+        UserBalance,
+        BalanceTransaction,
+        RedeemCode,
+        RedeemCodeBatch,
+        RedeemCodeUsageLog,
+    )
+    
+    logger.info(f"初始化数据库: {settings.database_url}")
+    async with engine.begin() as conn:
+        await conn.run_sync(Base.metadata.create_all)
+    logger.info("数据库初始化完成")
+
+
+async def close_db() -> None:
+    """关闭数据库连接"""
+    await engine.dispose()
+