Error Mapper for NestJS

A TypeScript library for NestJS that provides flexible error mapping from custom errors to response handlers.

Installation

npm install @seungkyu/error-mapper

Usage

1. Set global

Apply the interceptor globally so that error mapping works across all controllers and routes.

import {NestFactory, Reflector} from '@nestjs/core';
import {AppModule} from './app.module';
import {MapErrorInterceptor} from '@seungkyu/error-mapper';

async function bootstrap() {
    const app = await NestFactory.create(AppModule);

    const reflector = app.get(Reflector);

    app.useGlobalInterceptors(new MapErrorInterceptor(reflector));

    await app.listen(process.env.PORT ?? 3000);
}

bootstrap();

2. Set scope

Apply to specific controllers or routes

If you want to apply error mapping only to specific parts of your application, you can use @UseInterceptors.

@Controller()
@UseInterceptors(MapErrorInterceptor)
export class AppController {
    constructor(private readonly appService: AppService) {
    }
}

3. Internal Error Mapping

Transform one error into another custom error

import {Controller, Get, UseInterceptors} from '@nestjs/common';
import {AppService} from './app.service';
import {MapErrorInterceptor, MapError} from '@seungkyu/error-mapper';

export class SeungkyuSourceError extends Error {
    constructor() {
        super('SeungkyuSourceError constructor');
    }
}

export class SeungkyuTargetError extends Error {
    constructor() {
        super('SeungkyuTargetError constructor');
    }
}

@Controller()
@UseInterceptors(MapErrorInterceptor)
export class AppController {
    constructor(private readonly appService: AppService) {
    }

    @MapError({
        sourceError: SeungkyuSourceError,
        targetError: SeungkyuTargetError,
        message: 'InternalSeungkyuError mapped to BadRequestException',
    })
    @Get('seungkyu')
    getHello(): string {
        throw new SeungkyuSourceError();
        return this.appService.getHello();
    }
}

Configuration

| Option | Type | Required | Default | Description | |-------------|--------|----------|---------------------------------|-----------------------------------------------------------------------------------------------| | sourceError | Error | ✅ | - | The internal error class to match (e.g., UserNotFoundError). | | targetError | Error | ✅ | - | The exception class to be thrown when the source error is caught (e.g., BadRequestException). | | message | string | ❌ | error message in original error | An optional custom message to override the original error message. |

4. HTTP Error Mapping

Transform error into HTTP response (HttpException)

import {Controller, Get, HttpStatus, UseInterceptors} from '@nestjs/common';
import {AppService} from './app.service';
import {MapErrorInterceptor, MapError} from '@seungkyu/error-mapper';

export class SeungkyuSourceError extends Error {
    constructor() {
        super('SeungkyuSourceError constructor');
    }
}

@Controller()
@UseInterceptors(MapErrorInterceptor)
export class AppController {
    constructor(private readonly appService: AppService) {
    }

    @MapError({
        sourceError: SeungkyuSourceError,
        status: HttpStatus.BAD_REQUEST,
        message: 'mapped to status',
    })
    @Get('seungkyu')
    getHello(): string {
        throw new SeungkyuSourceError();
        return this.appService.getHello();
    }
}

Configuration

| Option | Type | Required | Default | Description | |-------------|--------|----------|---------------------------------|------------------------------------------------------------------| | sourceError | Error | ✅ | - | Error class to match (e.g., UserNotFoundError) | | status | number | ✅ | - | HTTP status code returned when the error is thrown | | message | string | ❌ | error message in original error | Optional custom message (defaults to the original error message) |

Example

Using with Swagger

case1: Custom error message

case2: Default error message

Contact

• Email: [email protected]