pino-pretty/lib/utils/prettify-object.js

Prettifier for Pino log lines

'use strict'

module.exports = prettifyObject

const {
  LOGGER_KEYS
} = require('../constants')

const stringifySafe = require('fast-safe-stringify')
const joinLinesWithIndentation = require('./join-lines-with-indentation')
const prettifyError = require('./prettify-error')

/**
 * @typedef {object} PrettifyObjectParams
 * @property {object} log The object to prettify.
 * @property {boolean} [excludeLoggerKeys] Indicates if known logger specific
 * keys should be excluded from prettification. Default: `true`.
 * @property {string[]} [skipKeys] A set of object keys to exclude from the
 *  * prettified result. Default: `[]`.
 * @property {PrettyContext} context The context object built from parsing
 * the options.
 */

/**
 * Prettifies a standard object. Special care is taken when processing the object
 * to handle child objects that are attached to keys known to contain error
 * objects.
 *
 * @param {PrettifyObjectParams} input
 *
 * @returns {string} The prettified string. This can be as little as `''` if
 * there was nothing to prettify.
 */
function prettifyObject ({
  log,
  excludeLoggerKeys = true,
  skipKeys = [],
  context
}) {
  const {
    EOL: eol,
    IDENT: ident,
    customPrettifiers,
    errorLikeObjectKeys: errorLikeKeys,
    objectColorizer,
    singleLine,
    colorizer
  } = context
  const keysToIgnore = [].concat(skipKeys)

  /* istanbul ignore else */
  if (excludeLoggerKeys === true) Array.prototype.push.apply(keysToIgnore, LOGGER_KEYS)

  let result = ''

  // Split object keys into two categories: error and non-error
  const { plain, errors } = Object.entries(log).reduce(({ plain, errors }, [k, v]) => {
    if (keysToIgnore.includes(k) === false) {
      // Pre-apply custom prettifiers, because all 3 cases below will need this
      const pretty = typeof customPrettifiers[k] === 'function'
        ? customPrettifiers[k](v, k, log, { colors: colorizer.colors })
        : v
      if (errorLikeKeys.includes(k)) {
        errors[k] = pretty
      } else {
        plain[k] = pretty
      }
    }
    return { plain, errors }
  }, { plain: {}, errors: {} })

  if (singleLine) {
    // Stringify the entire object as a single JSON line
    /* istanbul ignore else */
    if (Object.keys(plain).length > 0) {
      result += objectColorizer.greyMessage(stringifySafe(plain))
    }
    result += eol
    // Avoid printing the escape character on escaped backslashes.
    result = result.replace(/\\\\/gi, '\\')
  } else {
    // Put each object entry on its own line
    Object.entries(plain).forEach(([keyName, keyValue]) => {
      // custom prettifiers are already applied above, so we can skip it now
      let lines = typeof customPrettifiers[keyName] === 'function'
        ? keyValue
        : stringifySafe(keyValue, null, 2)

      if (lines === undefined) return

      // Avoid printing the escape character on escaped backslashes.
      lines = lines.replace(/\\\\/gi, '\\')

      const joinedLines = joinLinesWithIndentation({ input: lines, ident, eol })
      result += `${ident}${keyName}:${joinedLines.startsWith(eol) ? '' : ' '}${joinedLines}${eol}`
    })
  }

  // Errors
  Object.entries(errors).forEach(([keyName, keyValue]) => {
    // custom prettifiers are already applied above, so we can skip it now
    const lines = typeof customPrettifiers[keyName] === 'function'
      ? keyValue
      : stringifySafe(keyValue, null, 2)

    if (lines === undefined) return

    result += prettifyError({ keyName, lines, eol, ident })
  })

  return result
}