# SQLAlchemy 无效请求错误：会话已在刷新中。

- **ID:** `python/flask-sqlalchemy-session-scope`
- **领域:** python
- **类别:** data_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

在会话已经在刷新过程中尝试提交或刷新，通常由于嵌套事务导致。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 3.x | active | — | — |

## 解决方案

1. **** (95% 成功率)
   ```
   Ensure one commit per request: use Flask-SQLAlchemy's teardown to remove session.
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy(app)
# In route: db.session.add(obj); db.session.commit() only once
   ```
2. **** (85% 成功率)
   ```
   Use session.begin_nested() for subtransactions and commit at end.
   ```

## 无效尝试

- **** — Exacerbates nested transaction issues. (80% 失败率)
- **** — May lose changes and not solve the underlying concurrency issue. (60% 失败率)