refactor(db): 修复异步连接池无界增长，并完成 SQLAlchemy 2.0 迁移与分层归位 (#6320)

app/db/models/userconfig.py

@@ -1,5 +1,6 @@
-from sqlalchemy import Column, String, UniqueConstraint, JSON
-from sqlalchemy.orm import Session
+from typing import Any, Optional
+from sqlalchemy import String, UniqueConstraint, JSON, select
+from sqlalchemy.orm import Mapped, Session, mapped_column
 
 from app.db import db_query, db_update, get_id_column, Base
 
@@ -10,11 +11,11 @@ class UserConfig(Base):
     """
     id = get_id_column()
     # 用户名
-    username = Column(String)
+    username: Mapped[Optional[str]] = mapped_column(String)
     # 配置键
-    key = Column(String)
+    key: Mapped[Optional[str]] = mapped_column(String)
     # 值
-    value = Column(JSON)
+    value: Mapped[Optional[Any]] = mapped_column(JSON)
 
     __table_args__ = (
         # 用户名和配置键联合唯一
@@ -24,10 +25,9 @@ class UserConfig(Base):
     @classmethod
     @db_query
     def get_by_key(cls, db: Session, username: str, key: str):
-        return db.query(cls) \
-                 .filter(cls.username == username) \
-                 .filter(cls.key == key) \
-                 .first()
+        return db.execute(
+            select(cls).where(cls.username == username, cls.key == key)
+        ).scalars().first()
 
     @db_update
     def delete_by_key(self, db: Session, username: str, key: str):