Log an error without stack and other properties

[fengxinming]

winston@3

module.exports = format((info, opts) => {
  // ...
  return info;
});

When I log an error, and then the var info become an error, I expect the info.message is error

[DABH]

This is by design. If I understand correctly, you just want to log the error message without the other error properties. In that case, I would recommend just logging err.message or whatever property you desire, rather than logging the entire error object.

[aegyed91]

@DABH what to do if i want to log an error with stack trace and other properties?

logger.error(new Error('whatever'))

Is only going to log "whatever" and i am losing my stack trace. Because of this line: https://github.com/winstonjs/winston/blob/master/lib/winston/create-logger.js#L52

[DABH]

I think there is an unresolved issue there. I'm looking into it. Looks like this is the kind of workaround you need to do for now since Error properties are non-enumerable for some reason (thanks JS designers):

const winston = require('winston');
const format = winston.format;

const enumerateErrorFormat = format(info => {
  if (info.message instanceof Error) {
    info.message = Object.assign({
      message: info.message.message,
      stack: info.message.stack
    }, info.message);
  }

  if (info instanceof Error) {
    return Object.assign({
      message: info.message,
      stack: info.stack
    }, info);
  }

  return info;
});

const logger = winston.createLogger({
  level: 'debug',
  format: format.combine(
    enumerateErrorFormat(),
    format.json()
  ),
  transports: [
    new winston.transports.Console(),
  ],
});

logger.log('error', new Error('whatever'));

See #1338 . I'll see what I can do about figuring out a better solution for Errors that doesn't require this extra format snippet.

[aegyed91]

Thx @DABH for pointing to the correct issue, indeed this workaround seem to work.