Allow configuring formats per-transport within the same logger

[dandv]

What's the feature?

I have a logger with a console transport, and another transport that goes to a cloud-based logging service. For the console, I want to prefix messages with a timestamp, and colorize them. For the cloud-based logging service, I don't want timestamps because the service provides its own, and I don't want colors either.

Is this a feature you're prepared to implement, with support from us?

PRs for this feature were already sent: #427 and #422

Is configuring formats per transport already possible, but I haven't seen that capability explained in the README?

[dandv]

Nevermind, this is indeed possible, but the documentation completely omits mentioning the feature.

const logger = winston.createLogger({
  transports: [
    new winston.transports.File({
      filename: 'error.log', level: 'error',
      format: winston.format.simple(),
    }),
    new winston.transports.File({
      filename: 'combined.log', level: 'debug',
      format: winston.format.printf(info => `${new Date().toISOString(), ${info.message}`),
    }),
  ],
});

logger.error('prefixed by the timestamp only in `combined.log`');

[bradennapier]

Definitely add to docs plz

[ariestav]

@dandv The printf code in your comment does not work out of the box, there is a missing closing brace after the timestamp code.

So this line...

format: winston.format.printf(info => `${new Date().toISOString(), ${info.message}`),

...needs a closing brace like so

format: winston.format.printf(info => `${new Date().toISOString()}, ${info.message}`),

Thanks for the code and knowledge for custom formatting! Much appreciated!

[datnq102]

Nevermind, this indeed possible, but the documentation completely omits mentioning the feature.

const logger = winston.createLogger({
  transports: [
    new winston.transports.File({
      filename: 'error.log', level: 'error',
      format: winston.format.simple(),
    }),
    new winston.transports.File({
      filename: 'combined.log', level: 'debug',
      format: winston.format.printf(info => `${new Date().toISOString(), ${info.message}`),
    }),
  ],
});

logger.error('prefixed by the timestamp only in `combined.log`');

@dandv what if I have another format outside of transports and inside the create logger method. Which format will be applied?

[sarangnx]

Nevermind, this indeed possible, but the documentation completely omits mentioning the feature.

const logger = winston.createLogger({
  transports: [
    new winston.transports.File({
      filename: 'error.log', level: 'error',
      format: winston.format.simple(),
    }),
    new winston.transports.File({
      filename: 'combined.log', level: 'debug',
      format: winston.format.printf(info => `${new Date().toISOString(), ${info.message}`),
    }),
  ],
});

logger.error('prefixed by the timestamp only in `combined.log`');

@dandv what if I have another format outside of transports and inside the create logger method. Which format will be applied?

The one inside.