typescript 45 lines · 6 steps

Catch-all routes and error shaping in NestJS

A wildcard controller turns unmatched routes into 404s, and an exception filter renders every HttpException as consistent JSON.

Explained by highlit
NestJS Intermediate exception-handling routing middleware error-formatting
1import {
2 Controller,
3 All,
4 Req,
5 NotFoundException,
6 HttpException,
7 ExceptionFilter,
8 Catch,
9 ArgumentsHost,
10 HttpStatus,
11} from '@nestjs/common';
12import { Request, Response } from 'express';
13 
14@Controller('*')
15export class NotFoundController {
16 @All()
17 handleUnknownRoute(@Req() req: Request): never {
18 throw new NotFoundException(
19 `Cannot ${req.method} ${req.originalUrl}`,
20 );
21 }
22}
23 
24@Catch(HttpException)
25export class HttpExceptionFilter implements ExceptionFilter {
26 catch(exception: HttpException, host: ArgumentsHost) {
27 const ctx = host.switchToHttp();
28 const res = ctx.getResponse<Response>();
29 const req = ctx.getRequest<Request>();
30 const status = exception.getStatus();
31 const payload = exception.getResponse();
32 
33 res.status(status).json({
34 statusCode: status,
35 error: HttpStatus[status] ?? 'Error',
36 message:
37 typeof payload === 'string'
38 ? payload
39 : (payload as { message?: string | string[] }).message ??
40 exception.message,
41 path: req.originalUrl,
42 timestamp: new Date().toISOString(),
43 });
44 }
45}
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1A wildcard @Controller('*') gives you a single place to reject every route your app doesn't explicitly handle.
  2. 2An ExceptionFilter lets you intercept thrown exceptions and control the exact response body clients receive.
  3. 3Normalizing error payloads to a fixed shape makes APIs predictable for the clients that consume them.

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