Exceptions in NestJs

official Implementations: https://docs.nestjs.com/exception-filters

General Exceptions

{
  "statusCode": 500,
  "message": "Internal server error"
}

Overriding the entire response Body

throw new HttpException({
    status: HttpStatus.FORBIDDEN,
    error: 'This is a custom message',
  }, HttpStatus.FORBIDDEN);
//Yields
{
  "status": 403,
  "error": "This is a custom message"
}

But It still Lacks the Control, so what we can do is create a filter for exception for showing custom response and catching specific response such as Internal server error.

src/common/filter/http-exception.filter.ts

import {
  ArgumentsHost,
  Catch,
  ExceptionFilter,
  HttpException,
} from '@nestjs/common';
import { Request, Response } from 'express';
export interface ErrorResponse {
  timestamp: string;
  path: string;
  error: {
    name: string;
    message: Object | string;
  };
}
@Catch(HttpException)
export class HttpExceptionFilter implements ExceptionFilter {
  catch(exception: HttpException, host: ArgumentsHost) {
    const ctx = host.switchToHttp();
    const response = ctx.getResponse<Response>();
    const request = ctx.getRequest<Request>();
    let status = exception.getStatus();
    let name = exception.getResponse();
    let errorResponse: ErrorResponse = {
      timestamp: new Date().toISOString(),
      path: request.url,
      error: {
        name: status == 500 ? 
                        'Unknown' : 
                         name['error'] ?          
                         name['error'] : 
                         name,
        message: status == 500 ? 
                           'Something Went Wrong' : 
                            exception.message,
      },
    };
    //Finally Send the Modified Response
    response.status(
                      status == 500 ? 
                      400 : status
                    ).json(errorResponse);
  }
}

Use This Filter in the Controller Level or the Request Level as required

import { 
         HttpExceptionFilter 
       } from 'src/common/filter/http-exception.filter';
@UseFilters(new HttpExceptionFilter())

If You want to set it up in the Global Scope then

import { Module } from '@nestjs/common';
//Checky Nest JS,Why is this not in the documentation
import { APP_FILTER } from '@nestjs/core';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { HttpExceptionFilter } from './common/filters/http-exception.filter';
import { AppConfigModule } from './config/app/app-config.module';
@Module({
  imports: [AppConfigModule],
  controllers: [AppController],
  providers: [
    {
      provide: APP_FILTER, // <-- See This
      useValue: new HttpExceptionFilter(),
    },
    AppService,
  ],
})
export class AppModule {}