ln-772-error-handler-setup

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ln-772-error-handler-setup

Type: L3 Worker Category: 7XX Project Bootstrap Parent: ln-770-crosscutting-setup

Configures global error handling for .NET and Python backend applications.

类型： L3 工作流 分类： 7XX 项目初始化 父节点： ln-770-crosscutting-setup

为.NET和Python后端应用配置全局错误处理。

Overview

概述

Aspect	Details
Input	Context Store from ln-770
Output	Exception handling middleware and custom exceptions
Stacks	.NET (ASP.NET Core Middleware), Python (FastAPI exception handlers)

方面	详情
输入	来自ln-770的上下文存储
输出	异常处理中间件和自定义异常
技术栈	.NET (ASP.NET Core Middleware), Python (FastAPI exception handlers)

Phase 1: Receive Context

阶段1：接收上下文

Accept Context Store from coordinator.

Required Context:

```
STACK
```
: .NET or Python
```
FRAMEWORK
```
: ASP.NET Core or FastAPI
```
PROJECT_ROOT
```
: Project directory path
```
ENVIRONMENT
```
: Development or Production

Idempotency Check:

.NET: Grep for

GlobalExceptionMiddleware

UseExceptionHandler

Python: Grep for

@app.exception_handler

exception_handlers.py

If found: Return
```
{ "status": "skipped" }
```

接收来自协调器的上下文存储。

必填上下文：

```
STACK
```
: .NET 或 Python
```
FRAMEWORK
```
: ASP.NET Core 或 FastAPI
```
PROJECT_ROOT
```
: 项目目录路径
```
ENVIRONMENT
```
: 开发环境或生产环境

幂等性检查：

.NET: Grep for

GlobalExceptionMiddleware

UseExceptionHandler

Python: Grep for

@app.exception_handler

exception_handlers.py

若已存在：返回
```
{ "status": "skipped" }
```

Phase 2: Research Error Handling Patterns

阶段2：研究错误处理模式

Use MCP tools to get up-to-date documentation.

For .NET:

MCP ref: "ASP.NET Core global exception handling middleware"
Context7: /dotnet/aspnetcore

For Python:

MCP ref: "FastAPI exception handlers custom exceptions"
Context7: /tiangolo/fastapi

Key Patterns to Research:

Middleware pipeline positioning
Exception type mapping to HTTP status codes
ProblemDetails (RFC 7807) format
Development vs Production error details
Logging integration

使用MCP工具获取最新文档。

针对.NET：

MCP ref: "ASP.NET Core global exception handling middleware"
Context7: /dotnet/aspnetcore

针对Python：

MCP ref: "FastAPI exception handlers custom exceptions"
Context7: /tiangolo/fastapi

需研究的关键模式：

中间件管道定位
异常类型到HTTP状态码的映射
ProblemDetails (RFC 7807) 格式
开发环境与生产环境的错误详情差异
日志集成

Phase 3: Decision Points

阶段3：决策点

Q1: Error Response Format

Q1：错误响应格式

Option	Description
ProblemDetails (RFC 7807) (Recommended)	Standardized format, widely adopted
Custom Format	Project-specific requirements

选项	描述
ProblemDetails (RFC 7807)（推荐）	标准化格式，被广泛采用
自定义格式	符合项目特定需求

Q2: Error Detail Level

Q2：错误详情级别

Environment	Stack Trace	Inner Exceptions	Request Details
Development	✓ Show	✓ Show	✓ Show
Production	✗ Hide	✗ Hide	✗ Hide

环境	堆栈跟踪	内部异常	请求详情
开发环境	✓ 显示	✓ 显示	✓ 显示
生产环境	✗ 隐藏	✗ 隐藏	✗ 隐藏

Q3: Error Taxonomy

Q3：错误分类

Define standard error codes:

Code	HTTP Status	Description
`VALIDATION_ERROR`	400	Invalid input data
`UNAUTHORIZED`	401	Authentication required
`FORBIDDEN`	403	Insufficient permissions
`NOT_FOUND`	404	Resource not found
`CONFLICT`	409	Resource state conflict
`INTERNAL_ERROR`	500	Unexpected server error

定义标准错误码：

代码	HTTP状态码	描述
`VALIDATION_ERROR`	400	输入数据无效
`UNAUTHORIZED`	401	需要身份验证
`FORBIDDEN`	403	权限不足
`NOT_FOUND`	404	资源未找到
`CONFLICT`	409	资源状态冲突
`INTERNAL_ERROR`	500	服务器意外错误

Phase 4: Generate Configuration

阶段4：生成配置

.NET Output Files

.NET 输出文件

File	Purpose
`Middleware/GlobalExceptionMiddleware.cs`	Exception handling middleware
`Exceptions/AppException.cs`	Base exception class
`Exceptions/ValidationException.cs`	Validation errors
`Exceptions/NotFoundException.cs`	Not found errors
`Models/ErrorResponse.cs`	Error response model

Generation Process:

Use MCP ref to get current ASP.NET Core exception handling patterns
Generate GlobalExceptionMiddleware with:
- Exception type to HTTP status mapping
- Logging of exceptions
- ProblemDetails response format
- Environment-aware detail level
Generate custom exception classes

Registration Code:

csharp

app.UseMiddleware<GlobalExceptionMiddleware>();

文件	用途
`Middleware/GlobalExceptionMiddleware.cs`	异常处理中间件
`Exceptions/AppException.cs`	基础异常类
`Exceptions/ValidationException.cs`	验证错误类
`Exceptions/NotFoundException.cs`	资源未找到错误类
`Models/ErrorResponse.cs`	错误响应模型

生成流程：

使用MCP参考获取当前ASP.NET Core异常处理模式
生成GlobalExceptionMiddleware，包含：
- 异常类型到HTTP状态码的映射
- 异常日志记录
- ProblemDetails响应格式
- 感知环境的详情级别
生成自定义异常类

注册代码：

csharp

app.UseMiddleware<GlobalExceptionMiddleware>();

Python Output Files

Python 输出文件

File	Purpose
`exceptions/app_exceptions.py`	Custom exception classes
`exceptions/handlers.py`	FastAPI exception handlers
`models/error_response.py`	Pydantic error models

Generation Process:

Use MCP ref to get current FastAPI exception handling patterns
Generate exception handlers with:
- HTTPException handling
- Custom AppException handling
- Validation error handling
- Request validation error handling
Generate custom exception classes

Registration Code:

python

app.add_exception_handler(AppException, app_exception_handler)
app.add_exception_handler(RequestValidationError, validation_exception_handler)

文件	用途
`exceptions/app_exceptions.py`	自定义异常类
`exceptions/handlers.py`	FastAPI异常处理器
`models/error_response.py`	Pydantic错误模型

生成流程：

使用MCP参考获取当前FastAPI异常处理模式
生成异常处理器，包含：
- HTTPException处理
- 自定义AppException处理
- 验证错误处理
- 请求验证错误处理
生成自定义异常类

注册代码：

python

app.add_exception_handler(AppException, app_exception_handler)
app.add_exception_handler(RequestValidationError, validation_exception_handler)

Phase 5: Validate

阶段5：验证

Validation Steps:

Syntax check:

.NET:
```
dotnet build --no-restore
```

Python:

python -m py_compile exceptions/handlers.py

Test error handling:
- Create test endpoint that throws exception
- Verify error response format
- Check that stack trace hidden in Production

Expected Error Response (ProblemDetails):

json

{
  "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1",
  "title": "Validation Error",
  "status": 400,
  "detail": "Invalid input data",
  "instance": "/api/users",
  "errors": [
    { "field": "email", "message": "Invalid email format" }
  ],
  "traceId": "abc-123-def-456"
}

验证步骤：

语法检查：

.NET:
```
dotnet build --no-restore
```

Python:

python -m py_compile exceptions/handlers.py

测试错误处理：
- 创建抛出异常的测试端点
- 验证错误响应格式
- 检查生产环境中堆栈跟踪是否被隐藏

预期错误响应（ProblemDetails格式）：

json

{
  "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1",
  "title": "Validation Error",
  "status": 400,
  "detail": "Invalid input data",
  "instance": "/api/users",
  "errors": [
    { "field": "email", "message": "Invalid email format" }
  ],
  "traceId": "abc-123-def-456"
}

Return to Coordinator

返回协调器

json

{
  "status": "success",
  "files_created": [
    "Middleware/GlobalExceptionMiddleware.cs",
    "Exceptions/AppException.cs",
    "Models/ErrorResponse.cs"
  ],
  "packages_added": [],
  "registration_code": "app.UseMiddleware<GlobalExceptionMiddleware>();",
  "message": "Configured global exception handling"
}

json

{
  "status": "success",
  "files_created": [
    "Middleware/GlobalExceptionMiddleware.cs",
    "Exceptions/AppException.cs",
    "Models/ErrorResponse.cs"
  ],
  "packages_added": [],
  "registration_code": "app.UseMiddleware<GlobalExceptionMiddleware>();",
  "message": "Configured global exception handling"
}

Reference Links

参考链接

Version: 2.0.0 Last Updated: 2026-01-10

版本： 2.0.0 最后更新： 2026-01-10