node.jsnestjs

NestJS - async operation inside error filter


In our NestJS-app we've set up a custom error filter, that catches a certain type of error. For those errors we need to perform a request to elasticsearch in order to log the corresponding error information. Since the elasticsearch request is async I've defined the catch method async:

@Catch(MyExceptionType)
@Injectable()
export class MyExceptionFilter implements ExceptionFilter {

    constructor(private readonly elasticsearchService: ElasticsearchService) { }

    async catch(exception: MyExceptionType, host: ArgumentsHost) {
        const ctx      = host.switchToHttp();
        const request  = ctx.getRequest<MyRequestModel>();
        const response = ctx.getResponse<MyResponseModel>();

        const elasticSearchPayload = PayloadBuilder.of(request, exception);
        await this.elasticsearchService.report(elasticSearchPayload);
        // ...
        response.status(exception.getStatus()).json({...});
    }
}

Now - so far this works fine, but I'm wondering if this is actually ok to do, as the ExceptionFilter interface strictly declares catch to be a synchronous method.

Could we run into trouble doing this?


Solution

  • ExceptionFilters are to define your error handling logic. I don't think it should be an issue having it async, Nest just won't wait for the logic to finish, however, it shouldn't invoke any other exception handlers due to how it's custom filter code is written.