feat: SQLite → PostgreSQL 迁移代码改动

按 docs/数据库迁移.md 第 3 节扫雷清单落地代码层改动:

- pyproject.toml: 新增 psycopg[binary]>=3.1 依赖 (psycopg3, SQLAlchemy 2.0 时代默认, 不要再装 psycopg2)

- app/db/session.py: 非 SQLite 自动加连接池参数
  - pool_size=10, max_overflow=20, pool_recycle=3600
  - SQLite 单文件不池化, _is_sqlite 判断分支保留以便本地 dev 临时回退

- app/models/savings.py: dishes 列从 JSON 改为 JSONB
  - PG 上能用 GIN 索引和 jsonb 操作符
  - SQLite 上 JSON 实际是 TEXT, 切到 PG 后用 JSON 类型存的是 json 不是 jsonb

- alembic/versions/ef96beb47b1e_*.py: 新增迁移把 savings_record.dishes 从 json 转 jsonb
  - 用 op.get_bind().dialect.name 判断 PG 才执行 ALTER COLUMN
  - SQLite 上是 no-op (SQLite 没有 jsonb 类型)
  - 旧的 savings_shop_dishes.py 迁移保持 sa.JSON() 不动 (按文档"不改老迁移"原则)

本地切 PG 验证: 10 张表全部建出, dishes 字段为 jsonb 类型,
登录/me/美团 feed 三个真接口全 200, user 数据正确写入 PG.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

alembic/versions/ef96beb47b1e_convert_savings_record_dishes_from_json_.py

@@ -0,0 +1,36 @@
+"""convert savings_record.dishes from json to jsonb
+
+PG only. SQLite 上 JSON/JSONB 都是 TEXT, 此迁移是 no-op。
+
+Revision ID: ef96beb47b1e
+Revises: c8d9e0f1a2b3
+Create Date: 2026-05-29 10:57:21.471774
+"""
+from typing import Sequence, Union
+
+from alembic import op
+from sqlalchemy.dialects.postgresql import JSONB
+
+
+revision: str = 'ef96beb47b1e'
+down_revision: Union[str, Sequence[str], None] = 'c8d9e0f1a2b3'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    if op.get_bind().dialect.name != "postgresql":
+        return
+    op.execute(
+        "ALTER TABLE savings_record "
+        "ALTER COLUMN dishes TYPE JSONB USING dishes::JSONB"
+    )
+
+
+def downgrade() -> None:
+    if op.get_bind().dialect.name != "postgresql":
+        return
+    op.execute(
+        "ALTER TABLE savings_record "
+        "ALTER COLUMN dishes TYPE JSON USING dishes::JSON"
+    )

app/db/session.py

@@ -27,19 +27,25 @@ def _ensure_sqlite_dir(url: str) -> None:
 
 _ensure_sqlite_dir(settings.DATABASE_URL)
 
+_is_sqlite = settings.DATABASE_URL.startswith("sqlite")
+
 # SQLite 跨线程访问要 check_same_thread=False;PG/MySQL 不需要这个参数
 _connect_args: dict = {}
-if settings.DATABASE_URL.startswith("sqlite"):
+if _is_sqlite:
     _connect_args["check_same_thread"] = False
 
-engine = create_engine(
-    settings.DATABASE_URL,
-    connect_args=_connect_args,
+_engine_kwargs: dict = {
+    "connect_args": _connect_args,
     # echo 在 dev 下打 SQL,生产关掉
-    echo=settings.APP_DEBUG and not settings.is_prod,
-    future=True,
-    pool_pre_ping=True,
-)
+    "echo": settings.APP_DEBUG and not settings.is_prod,
+    "future": True,
+    "pool_pre_ping": True,
+}
+# SQLite 用单文件不需要池;PG/MySQL 必须显式池化 + recycle 防 idle 断连
+if not _is_sqlite:
+    _engine_kwargs.update(pool_size=10, max_overflow=20, pool_recycle=3600)
+
+engine = create_engine(settings.DATABASE_URL, **_engine_kwargs)
 
 SessionLocal = sessionmaker(bind=engine, autocommit=False, autoflush=False, expire_on_commit=False)
 

app/models/savings.py

@@ -8,7 +8,8 @@ from __future__ import annotations
 
 from datetime import datetime
 
-from sqlalchemy import JSON, DateTime, ForeignKey, Integer, String, func
+from sqlalchemy import DateTime, ForeignKey, Integer, String, func
+from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.orm import Mapped, mapped_column
 
 from app.db.base import Base
@@ -28,8 +29,8 @@ class SavingsRecord(Base):
     title: Mapped[str | None] = mapped_column(String(128), nullable=True)
     # 店铺名(订单明细卡标题,如「窑鸡王（王府井店）」)
     shop_name: Mapped[str | None] = mapped_column(String(128), nullable=True)
-    # 菜品名列表(JSON),前 2 道直接展示,其余收进「还有 N 道菜」展开。SQLite 存为 TEXT。
-    dishes: Mapped[list[str]] = mapped_column(JSON, nullable=False, default=list)
+    # 菜品名列表(JSONB),PG 上可建 GIN 索引,前 2 道直接展示,其余收进「还有 N 道菜」展开。
+    dishes: Mapped[list[str]] = mapped_column(JSONB, nullable=False, default=list)
     # 来源:demo(演示) / compare(真实比价上报)
     source: Mapped[str] = mapped_column(String(16), nullable=False, default="compare")
 

pyproject.toml

@@ -17,6 +17,9 @@ dependencies = [
     "sqlalchemy>=2.0.35",
     "alembic>=1.13.3",
 
+    # PostgreSQL 驱动 (psycopg3, SQLAlchemy 2.0 时代默认, 不要再装 psycopg2)
+    "psycopg[binary]>=3.1",
+
     # JWT 签名 / 校验
     "pyjwt[crypto]>=2.9.0",