[Bug]: Nested objects in defaultMeta won't merge with nested objects in the log meta

[MitchellCash]

🔎 Search Terms

defaultMeta, nested, object

The problem

When defaultMeta sets a nested object it won't be merged with another nested object in the log meta using the same key. Instead, the nested object in the log meta overrides the defaultMeta nested object, instead of merging them.

This might be by design due to any performance or other concerns of iterating through nested objects, but thought I would raise it nonetheless.

What version of Winston presents the issue?

v3.7.2

What version of Node are you using?

v16.14.1

If this worked in a previous version of Winston, which was it?

No response

Minimum Working Example

import { hostname } from 'node:os';
import * as winston from 'winston';

const logger = winston.createLogger({
  level: 'info',
  format: winston.format.combine(winston.format.json()),
  transports: [new winston.transports.File({ filename: 'logs/application.log' })],
  defaultMeta: {
    syslog: {
      hostname: hostname()
    }
  }
});

logger.info(undefined, { env: "dev" };

// RESULT (✅):
// {"env":"dev","syslog":{"hostname":"app-server-01"}}

logger.info(undefined, { env: "dev", syslog: { timestamp: new Date() }};

// RESULT (❌):
// {"env":"dev","syslog":{"timestamp":"2022-04-07T09:15:41.636Z"}}

// EXPECTATION (✅):
// {"env":"dev","syslog":{"hostname":"app-server-01","timestamp":"2022-04-07T09:15:41.636Z"}}

Additional information

No response

[MitchellCash]

Apologies, I didn't even look at the pinned issue #2029 which links to #1884, both of which cover my described issue! Will close this and look forward to future updates!

[wbt]

@MitchellCash Can you try temporarily using 3.7.1 and see if that solves your issue?
It accidentally broke some code (#2103) without a major version bump, so we quickly rolled back the changes in a 3.7.2, but anticipate re-rolling out those changes once #2103 is fixed. It would be nice if you can test and verify whether that's going to fix your issue when the rollout happens, and running 3.7.1 is a reasonable strategy to test for that.

[MitchellCash]

@wbt I pinned to version 3.7.1 and unfortunately it didn't fix the above issue. I performed the same tests outlined in the top post and had the same results.

[wbt]

Hmm, that's unfortunate. It might be a good test case for @maverick1872 to have a look at.

[maverick1872]

This is by design currently. As it stands the meta implementation doesn't support a deep merge strategy as it's a departure from the current merge strategy.

Id like to get add a configuration that allows one to define a merge strategy on a given logger instance but fixing the current issues is higher priority. Unfortunately I'm pretty slammed with other responsibilities right now so I've been unable to diagnose the issues with the latest release let alone investigate new features.

I welcome any contributions though! 😁