feature request: before log hook

[alexey2baranov]

Hi there!
Can you add beforeLog hook into logger constructor, pls

It is very handful for setting additional data before logging payload by streams. For example we would like to use it to store additional data from cls-context like req_id and user.

For example:
logger.debug( {sum: 200}, "add sum to account")
can be added some additional data from beforeLog hook {req_id: context.req_id, user: context.user}

[alexey2baranov]

maybe helps somebody

import Logger from "bunyan";

export default class extends Logger {
  _emit() {
    this.emit('beforeEmit', ...arguments)
    // @ts-ignore
    super._emit(...arguments)
  }
}