改用mysql

backend/app/core/db.py

@@ -1,18 +1,17 @@
-"""SQLAlchemy 2.x 同步引擎 + 会话管理（MVP: SQLite）。
+"""SQLAlchemy 2.x 同步引擎 + 会话管理。
 
-切换 PostgreSQL 时（扩展接口 1）：
-1. DATABASE_URL 改为 postgresql+asyncpg://...
-2. 引擎换 create_async_engine + async_sessionmaker
-3. get_session 改 async generator + yield
-4. 业务层 Repository 调用加 await
+支持 MySQL / SQLite，通过 DATABASE_URL 自动切换。
 """
 
 from collections.abc import Generator
 
-from sqlalchemy import create_engine
+from sqlalchemy import create_engine, event, text
 from sqlalchemy.orm import Session, sessionmaker
 
 from app.core.config import get_settings
+from app.core.logging import get_logger
+
+logger = get_logger(__name__)
 
 _engine = None
 _session_factory: sessionmaker[Session] | None = None
@@ -22,24 +21,48 @@ def get_engine():
     global _engine
     if _engine is None:
         settings = get_settings()
-        _engine = create_engine(
-            settings.database_url,
-            pool_pre_ping=True,
-            echo=False,
-            # SQLite 专属：启用 WAL 模式（并发读 + 写串行化）
-            connect_args={"check_same_thread": False} if "sqlite" in settings.database_url else {},
-        )
-        # SQLite: 启用 WAL 模式与外键约束
-        if "sqlite" in settings.database_url:
-            from sqlalchemy import event, text
 
+        engine_kwargs = {
+            "pool_pre_ping": True,
+            "echo": False,
+        }
+
+        if settings.is_mysql:
+            # MySQL 配置
+            engine_kwargs.update({
+                "pool_size": 10,
+                "max_overflow": 20,
+                "pool_recycle": 3600,  # 1 小时回收连接，防止 MySQL 超时断开
+                "connect_args": {
+                    "charset": "utf8mb4",
+                },
+            })
+        elif settings.is_sqlite:
+            # SQLite 配置
+            engine_kwargs["connect_args"] = {"check_same_thread": False}
+
+        _engine = create_engine(settings.database_url, **engine_kwargs)
+
+        # SQLite: 启用 WAL 模式 + 外键约束
+        if settings.is_sqlite:
             @event.listens_for(_engine, "connect")
-            def _set_sqlite_pragma(dbapi_conn, _):  # type: ignore[no-untyped-def]
+            def _set_sqlite_pragma(dbapi_conn, _):
                 cursor = dbapi_conn.cursor()
                 cursor.execute("PRAGMA journal_mode=WAL")
                 cursor.execute("PRAGMA foreign_keys=ON")
                 cursor.close()
 
+        # MySQL: 设置字符集和 SQL 模式
+        if settings.is_mysql:
+            @event.listens_for(_engine, "connect")
+            def _set_mysql_session(dbapi_conn, _):
+                cursor = dbapi_conn.cursor()
+                cursor.execute("SET NAMES utf8mb4")
+                cursor.execute("SET SESSION sql_mode='STRICT_TRANS_TABLES,NO_ZERO_DATE,NO_ZERO_IN_DATE,ERROR_FOR_DIVISION_BY_ZERO'")
+                cursor.close()
+
+        logger.info("Database engine created: %s", "MySQL" if settings.is_mysql else "SQLite")
+
     return _engine
 
 
@@ -73,4 +96,4 @@ def dispose_engine() -> None:
     if _engine is not None:
         _engine.dispose()
     _engine = None
-    _session_factory = None
+    _session_factory = None