Backend Error Handling

Backend Error Handling

Service Pattern

async getById(id: string) {
  try {
    const item = await this.prisma.feature.findUnique({ where: { id } });
    if (!item) throw new CustomHttpException('Not found', HttpStatus.NOT_FOUND);
    return item;
  } catch (error) {
    handleException(error, false, {});
  }
}

Every public service method uses try/catch → handleException.

Throw Business Errors

throw new CustomHttpException('Slug already exists', HttpStatus.BAD_REQUEST);
throw new CustomHttpException('Not found', HttpStatus.NOT_FOUND);
throw new CustomForbiddenException('Must be admin');

Response Helpers

// Single entity
return sendSuccessfulResponse(data);
// → { status: 'success', data }

// List with count
return sendCustomResponse({ data: requests, count });
// → { status: 'success', data, count }

// Custom fields
return sendCustomResponse({ data, count, types });

Never return raw Prisma objects from controllers.

Global Filters

Register once in app.module.ts:

{ provide: APP_FILTER, useClass: AllExceptionsFilter },
{ provide: APP_FILTER, useClass: PrismaExceptionFilter },

Error Response Shapes

Custom Exceptions

CustomHttpException, CustomBadRequestException, CustomNotFoundException, CustomForbiddenException — flag customError: true skips verbose logging.

Logging

File logs in logs/ — daily rotation. LoggingInterceptor for request timing. Uncaught → logs/uncaughtException.txt.