错误处理模式 是做什么的？
面向生产应用的、一致且健壮的错误处理模式。
何时激活
- 为新模块或服务设计错误类型或异常层次结构
- 为不可靠的外部依赖添加重试逻辑或断路器
- 审查 API 端点以检查缺失的错误处理
- 实现面向用户的错误消息和反馈
- 调试级联故障或静默错误吞没
核心原则
- 快速失败和显式报错 — 在错误发生的边界处将其暴露；不要将其埋没
- 类型化错误优于字符串消息 — 错误是带有结构的一等公民
- 用户消息 ≠ 开发者消息 — 向用户显示友好的文本，在服务端记录完整的上下文
- 绝不静默吞没错误 — 每个
catch块必须要么处理、要么重新抛出、要么记录日志 - 错误是 API 契约的一部分 — 记录客户端可能收到的每个错误代码
TypeScript / JavaScript
类型化错误类
// 为你的领域定义错误层次结构
export class AppError extends Error {
constructor(
message: string,
public readonly code: string,
public readonly statusCode: number = 500,
public readonly details?: unknown,
) {
super(message)
this.name = this.constructor.name
// 在转译为 ES5 JavaScript 后维持正确的原型链。
// 当扩展内置的 Error 类时，`instanceof` 检查（例如 `error instanceof NotFoundError`）
// 需要此设置才能正确工作。
Object.setPrototypeOf(this, new.target.prototype)
}
}
export class NotFoundError extends AppError {
constructor(resource: string, id: string) {
super(`${resource} not found: ${id}`, 'NOT_FOUND', 404)
}
}
export class ValidationError extends AppError {
constructor(message: string, details: { field: string; message: string }[]) {
super(message, 'VALIDATION_ERROR', 422, details)
}
}
export class UnauthorizedError extends AppError {
constructor(reason = 'Authentication required') {
super(reason, 'UNAUTHORIZED', 401)
}
}
export class RateLimitError extends AppError {
constructor(public readonly retryAfterMs: number) {
super('Rate limit exceeded', 'RATE_LIMITED', 429)
}
}
Result 模式（无抛出风格）
适用于预期会发生失败且失败很常见的操作（解析、外部调用）：
type Result<T, E = AppError> =
| { ok: true; value: T }
| { ok: false; error: E }
function ok<T>(value: T): Result<T> {
return { ok: true, value }
}
function err<E>(error: E): Result<never, E> {
return { ok: false, error }
}
// 用法
async function fetchUser(id: string): Promise<Result<User>> {
try {
const user = await db.users.findUnique({ where: { id } })
if (!user) return err(new NotFoundError('User', id))
return ok(user)
} catch (e) {
return err(new AppError('Database error', 'DB_ERROR'))
}
}
const result = await fetchUser('abc-123')
if (!result.ok) {
// TypeScript 在此处知道 result.error 的类型
logger.error('Failed to fetch user', { error: result.error })
return
}
// TypeScript 在此处知道 result.value 的类型
console.log(result.value.email)
API 错误处理器（Next.js / Express）
import { NextRequest, NextResponse } from 'next/server'
function handleApiError(error: unknown): NextResponse {
// 已知的应用错误
if (error instanceof AppError) {
return NextResponse.json(
{
error: {
code: error.code,
message: error.message,
...(error.details ? { details: error.details } : {}),
},
},
{ status: error.statusCode },
)
}
// Zod 验证错误
if (error instanceof z.ZodError) {
return NextResponse.json(
{
error: {
code: 'VALIDATION_ERROR',
message: 'Request validation failed',
details: error.issues.map(i => ({
field: i.path.join('.'),
message: i.message,
})),
},
},
{ status: 422 },
)
}
// 意外错误 — 记录详情，返回通用消息
console.error('Unexpected error:', error)
return NextResponse.json(
{ error: { code: 'INTERNAL_ERROR', message: 'An unexpected error occurred' } },
{ status: 500 },
)
}
export async function POST(req: NextRequest) {
try {
// ... 处理逻辑
} catch (error) {
return handleApiError(error)
}
}
React 错误边界
import { Component, ErrorInfo, ReactNode } from 'react'
interface Props {
fallback: ReactNode
onError?: (error: Error, info: ErrorInfo) => void
children: ReactNode
}
interface State {
hasError: boolean
error: Error | null
}
export class ErrorBoundary extends Component<Props, State> {
state: State = { hasError: false, error: null }
static getDerivedStateFromError(error: Error): State {
return { hasError: true, error }
}
componentDidCatch(error: Error, info: ErrorInfo) {
this.props.onError?.(error, info)
console.error('Unhandled React error:', error, info)
}
render() {
if (this.state.hasError) return this.props.fallback
return this.props.children
}
}
// 用法
<ErrorBoundary fallback={<p>Something went wrong. Please refresh.</p>}>
<MyComponent />
</ErrorBoundary>
Python
自定义异常层次结构
class AppError(Exception):
"""基础应用错误。"""
def __init__(self, message: str, code: str, status_code: int = 500):
super().__init__(message)
self.code = code
self.status_code = status_code
class NotFoundError(AppError):
def __init__(self, resource: str, id: str):
super().__init__(f"{resource} not found: {id}", "NOT_FOUND", 404)
class ValidationError(AppError):
def __init__(self, message: str, details: list[dict] | None = None):
super().__init__(message, "VALIDATION_ERROR", 422)
self.details = details or []
FastAPI 全局异常处理器
from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse
app = FastAPI()
@app.exception_handler(AppError)
async def app_error_handler(request: Request, exc: AppError) -> JSONResponse:
return JSONResponse(
status_code=exc.status_code,
content={"error": {"code": exc.code, "message": str(exc)}},
)
@app.exception_handler(Exception)
async def generic_error_handler(request: Request, exc: Exception) -> JSONResponse:
# 记录完整详情，返回通用消息
logger.exception("Unexpected error", exc_info=exc)
return JSONResponse(
status_code=500,
content={"error": {"code": "INTERNAL_ERROR", "message": "An unexpected error occurred"}},
)
Go
哨兵错误与错误包装
package domain
import "errors"
// 用于类型检查的哨兵错误
var (
ErrNotFound = errors.New("not found")
ErrUnauthorized = errors.New("unauthorized")
ErrConflict = errors.New("conflict")
)
// 使用上下文包装错误 — 绝不丢失原始错误
func (r *UserRepository) FindByID(ctx context.Context, id string) (*User, error) {
user, err := r.db.QueryRow(ctx, "SELECT * FROM users WHERE id = $1", id)
if errors.Is(err, sql.ErrNoRows) {
return nil, fmt.Errorf("user %s: %w", id, ErrNotFound)
}
if err != nil {
return nil, fmt.Errorf("querying user %s: %w", id, err)
}
return user, nil
}
// 在处理程序级别，解包以确定响应
func (h *Handler) GetUser(w http.ResponseWriter, r *http.Request) {
user, err := h.service.GetUser(r.Context(), chi.URLParam(r, "id"))
if err != nil {
switch {
case errors.Is(err, domain.ErrNotFound):
writeError(w, http.StatusNotFound, "not_found", err.Error())
case errors.Is(err, domain.ErrUnauthorized):
writeError(w, http.StatusForbidden, "forbidden", "Access denied")
default:
slog.Error("unexpected error", "err", err)
writeError(w, http.StatusInternalServerError, "internal_error", "An unexpected error occurred")
}
return
}
writeJSON(w, http.StatusOK, user)
}
使用指数退避的重试
interface RetryOptions {
maxAttempts?: number
baseDelayMs?: number
maxDelayMs?: number
retryIf?: (error: unknown) => boolean
}
async function withRetry<T>(
fn: () => Promise<T>,
options: RetryOptions = {},
): Promise<T> {
const {
maxAttempts = 3,
baseDelayMs = 500,
maxDelayMs = 10_000,
retryIf = () => true,
} = options
let lastError: unknown
for (let attempt = 1; attempt <= maxAttempts; attempt++) {
try {
return await fn()
} catch (error) {
lastError = error
if (attempt === maxAttempts || !retryIf(error)) throw error
const jitter = Math.random() * baseDelayMs
const delay = Math.min(baseDelayMs * 2 ** (attempt - 1) + jitter, maxDelayMs)
await new Promise(resolve => setTimeout(resolve, delay))
}
}
throw lastError
}
// 用法：重试瞬态网络错误，不重试 4xx
const data = await withRetry(() => fetch('/api/data').then(r => r.json()), {
maxAttempts: 3,
retryIf: (error) => !(error instanceof AppError && error.statusCode < 500),
})
面向用户的错误消息
将错误代码映射为人类可读的消息。将技术细节排除在用户可见文本之外。
const USER_ERROR_MESSAGES: Record<string, string> = {
NOT_FOUND: 'The requested item could not be found.',
UNAUTHORIZED: 'Please sign in to continue.',
FORBIDDEN: "You don't have permission to do that.",
VALIDATION_ERROR: 'Please check your input and try again.',
RATE_LIMITED: 'Too many requests. Please wait a moment and try again.',
INTERNAL_ERROR: 'Something went wrong on our end. Please try again later.',
}
export function getUserMessage(code: string): string {
return USER_ERROR_MESSAGES[code] ?? USER_ERROR_MESSAGES.INTERNAL_ERROR
}
错误处理检查清单
在合并任何涉及错误处理的代码之前：
- 每个
catch块都处理、重新抛出或记录 — 没有静默吞没 - API 错误遵循标准信封格式
{ error: { code, message } } - 面向用户的消息不包含堆栈跟踪或内部细节
- 完整的错误上下文已在服务端记录
- 自定义错误类扩展了带有
code字段的基础AppError - 异步函数将错误暴露给调用者 — 没有无回退的“即发即忘”
- 重试逻辑仅重试可重试的错误（非 4xx 客户端错误）
- React 组件被
ErrorBoundary包裹以处理渲染错误