NestJS handle service exceptions

Question

I'm working on a NestJS app where my services are not always called by a controller or any http request at all. Rather some services are called by a cron schedule to periodically fetch data.

What would be the best way to handle errors in this scenario? I implemented a "catch-all" exception filter, but when my service is called "internally" (not by a controller/request), there error does not get caught and I have an uncaught promise error.

florian norbert bepunkt florian norbert bepunkt · Accepted Answer · 2020-03-09T22:22:03

See my question here: Use global nest module in decorator

This decorator catches errors of a class method and logs them. The logging part is not necessary, you could implement your own error handling logic.

import { Inject } from '@nestjs/common';
import { LoggerService } from '../../logger/logger.service';

export function logErrorDecorator(bubble = false) {
  const injectLogger = Inject(LoggerService);

  return (target: any, propertyKey: string, propertyDescriptor: PropertyDescriptor) => {
    injectLogger(target, 'logger'); // this is the same as using constructor(private readonly logger: LoggerService) in a class

    //get original method
    const originalMethod = propertyDescriptor.value;

    //redefine descriptor value within own function block
    propertyDescriptor.value = async function(...args: any[]) {
      try {
        return await originalMethod.apply(this, args);
      } catch (error) {
        const logger: LoggerService = this.logger;

        logger.setContext(target.constructor.name);
        logger.error(error.message, error.stack);

        // rethrow error, so it can bubble up
        if (bubble) {
          throw error;
        }
      }
    };
  };
}

With this decorator you can simply add the logErrorDecorator() to your service class methods

NestJS handle service exceptions

1 Answers