Ushio-cn-old/yimian/iot/mqtt/smartfarm/node_modules/pino/docs/API.md

Table of Contents

• Constructor
• Logger
  • .child
  • .level
  • .fatal
  • .error
  • .warn
  • .info
  • .debug
  • .trace
  • .flush
  • level-change (event)
  • .levels.values
  • .levels.labels
  • LOG_VERSION
  • .stdSerializers
    • .req
    • .res
    • .err
  • .pretty
  • .addLevel

module.exports

.pino([options], [stream])

Parameters:

• options (object):
  • safe (boolean): avoid error caused by circular references in the object tree. Default: true.
  • name (string): the name of the logger. Default: undefined.
  • serializers (object): an object containing functions for custom serialization of objects. These functions should return an JSONifiable object and they should never throw. Each property name of this object will match to a property name is logged objects.
  • timestamp (boolean): Enables or disables the inclusion of a timestamp in the log message. slowtime has no effect if this option is set to false. Defaults: true.
  • slowtime (boolean): Outputs ISO time stamps ('2016-03-09T15:18:53.889Z') instead of Epoch time stamps (1457536759176). WARNING: This option carries a 25% performance drop. We recommend using default Epoch timestamps and transforming logs after if required. The pino -t command will do this for you (see CLI). Default: false.
  • extreme (boolean): Enables extreme mode, yields an additional 60% performance (from 250ms down to 100ms per 10000 ops). There are trade-off's should be understood before usage. See Extreme mode explained. Default: false.
  • level (string): one of 'fatal', 'error', 'warn', 'info', 'debug', 'trace'; also 'silent' is supported to disable logging. Any other value defines a custom level and requires supplying a level value via levelVal. Default: 'info'.
  • levelVal (integer): when defining a custom log level via level, set to an integer value to define the new level. Default: undefined.
  • enabled (boolean): enables logging. Default: true
• stream (Writable): a writable stream where the logs will be written. Deafult: process.stdout

Example:

'use strict'

var pino = require('pino')
var logger = pino({
  name: 'myapp',
  safe: true,
  serializers: {
    req: pino.stdSerializers.req,
    res: pino.stdSerializers.res
  }
})

Discussion:

Returns a new logger instance.

Logger

.child(bindings)

Parameters:

• bindings (object): an object of key-value pairs to include in log lines as properties.

Example:

logger.child({ a: 'property' }).info('hello child!')
// generates
// {"pid":46497,"hostname":"MacBook-Pro-di-Matteo.local","level":30,"msg":"hello child!","time":1458124707120,"v":0,"a":"property"}

Discussion:

Creates a child logger, setting all key-value pairs in bindings as properties in the log lines. All serializers will be applied to the given pair.

Child loggers use the same output stream as the parent and inherit the current log level of the parent at the time they are spawned.

From v2.x.x the log level of a child is mutable (whereas in v1.x.x it was immutable), and can be set independently of the parent. If a level property is present in the object passed to child it will override the child logger level.

For example:

var logger = pino()
logger.level = 'error'
logger.info('nope') //does not log
var child = logger.child({foo: 'bar'})
child.info('nope again') //does not log
child.level = 'info'
child.info('hooray') //will log
logger.info('nope nope nope') //will not log, level is still set to error
logger.child({ foo: 'bar', level: 'debug' }).debug('debug!')

Child loggers inherit the serializers from the parent logger but it is possible to override them.

For example:

var pino = require('./pino')

var customSerializers = {
  test: function () {
    return 'this is my serializer'
  }
}
var child = pino().child({serializers: customSerializers})

child.info({test: 'should not show up'})

Will produce the following output:

{"pid":7971,"hostname":"mycomputer.local","level":30,"time":1469488147985,"test":"this is my serializer","v":1}

Also from version 2.x.x we can spawn child loggers from child loggers, for instance:

var logger = pino()
var child = logger.child({father: true})
var childChild = child.child({baby: true})

Child logger creation is fast:

benchBunyanCreation*10000: 1291.332ms
benchBoleCreation*10000: 1630.542ms
benchPinoCreation*10000: 352.330ms
benchPinoExtremeCreation*10000: 102.282ms

Logging through a child logger has little performance penalty:

benchBunyanChild*10000: 1343.933ms
benchBoleChild*10000: 1605.969ms
benchPinoChild*10000: 334.573ms
benchPinoExtremeChild*10000: 152.792ms

Spawning children from children has negligible overhead:

benchBunyanChildChild*10000: 1397.202ms
benchPinoChildChild*10000: 338.930ms
benchPinoExtremeChildChild*10000: 150.143ms

.level

Example:

logger.level = 'info'

Discussion:

Set this property to the desired logging level. In order of priority, available levels are:

1. 'fatal'
2. 'error'
3. 'warn'
4. 'info'
5. 'debug'
6. 'trace'

The logging level is a minimum level. For instance if logger.level is 'info' then all 'fatal', 'error', 'warn', and 'info' logs will be enabled.

You can pass 'silent' to disable logging.

.fatal([obj], msg, [...])

Parameters:

• obj (object): object to be serialized
• msg (string): the log message to write
• ... (*): format string values when msg is a format string

Discussion:

Log at 'fatal' level the given msg. If the first argument is an object, all its properties will be included in the JSON line. If more args follows msg, these will be used to format msg using util.format.

.error([obj], msg, [...])

Parameters:

• obj (object): object to be serialized
• msg (string): the log message to write
• ... (*): format string values when msg is a format string

Discussion:

Log at 'error' level the given msg. If the first argument is an object, all its properties will be included in the JSON line. If more args follows msg, these will be used to format msg using util.format.

.warn([obj], msg, [...])

Parameters:

• obj (object): object to be serialized
• msg (string): the log message to write
• ... (*): format string values when msg is a format string

Discussion:

Log at 'warn' level the given msg. If the first argument is an object, all its properties will be included in the JSON line. If more args follows msg, these will be used to format msg using util.format.

.info([obj], msg, [...])

Parameters:

• obj (object): object to be serialized
• msg (string): the log message to write
• ... (*): format string values when msg is a format string

Discussion:

Log at 'info' level the given msg. If the first argument is an object, all its properties will be included in the JSON line. If more args follows msg, these will be used to format msg using util.format.

.debug([obj], msg, [...])

Parameters:

• obj (object): object to be serialized
• msg (string): the log message to write
• ... (*): format string values when msg is a format string

Discussion:

Log at 'debug' level the given msg. If the first argument is an object, all its properties will be included in the JSON line. If more args follows msg, these will be used to format msg using util.format.

.trace([obj], msg, [...])

Parameters:

• obj (object): object to be serialized
• msg (string): the log message to write
• ... (*): format string values when msg is a format string

Discussion:

Log at 'trace' level the given msg. If the first argument is an object, all its properties will be included in the JSON line. If more args follows msg, these will be used to format msg using util.format.

.flush()

Discussion:

Flushes the content of the buffer in extreme mode. It has no effect if extreme mode is not enabled.

.on('level-change', fn)

Example:

var listener = function (lvl, val, prevLvl, prevVal) {
  console.log(lvl, val, prevLvl, prevVal)
}
logger.on('level-change', listener)
logger.level = 'trace' // trigger console message
logger.removeListener('level-change', listener)
logger.level = 'info' // no message, since listener was removed

Discussion:

Registers a listener function that is triggered when the level is changed.

The listener is passed four arguments: levelLabel, levelValue, previousLevelLabel, previousLevelValue.

Note: When browserified, this functionality will only be available if the events module has been required elsewhere (e.g. if you're using streams in the browser). This allows for a trade-off between bundle size and functionality.

.levels.values

Example:

pino.levels.values.error === 50 // true

Discussion:

Returns the mappings of level names to their respective internal number representation. This property is available as a static property or as an instance property.

.levels.labels

Example:

pino.levels.labels[50] === 'error' // true

Discussion:

Returns the mappings of level internal level numbers to their string representations. This property is available as a static property or as an instance property.

.LOG_VERSION

Discussion:

Read only. Holds the current log format version (as output in the v property of each log record). This property is available as a static property or as an instance property.

.stdSerializers

Available as a static property, the stdSerializers provide functions for serializing objects common to many projects.

.req

Generates a JSONifiable object from the HTTP request object passed to the createServer callback of Node's HTTP server.

It returns an object in the form:

{
  pid: 93535,
  hostname: 'your host',
  level: 30,
  msg: 'my request',
  time: '2016-03-07T12:21:48.766Z',
  v: 0,
  req: {
    method: 'GET',
    url: '/',
    headers: {
      host: 'localhost:50201',
      connection: 'close'
    },
    remoteAddress: '::ffff:127.0.0.1',
    remotePort: 50202
  }
}

.res

Generates a JSONifiable object from the HTTP response object passed to the createServer callback of Node's HTTP server.

It returns an object in the form:

{
  pid: 93581,
  hostname: 'myhost',
  level: 30,
  msg: 'my response',
  time: '2016-03-07T12:23:18.041Z',
  v: 0,
  res: {
    statusCode: 200,
    header: 'HTTP/1.1 200 OK\r\nDate: Mon, 07 Mar 2016 12:23:18 GMT\r\nConnection: close\r\nContent-Length: 5\r\n\r\n'
  }
}

.err

Serializes an Error object if passed in as an property.

{
  "pid": 40510,
  "hostname": "MBP-di-Matteo",
  "level": 50,
  "msg": "an error",
  "time": 1459433282301,
  "v": 1,
  "type": "Error",
  "stack": "Error: an error\n    at Object.<anonymous> (/Users/matteo/Repositories/pino/example.js:16:7)\n    at Module._compile (module.js:435:26)\n    at Object.Module._extensions..js (module.js:442:10)\n    at Module.load (module.js:356:32)\n    at Function.Module._load (module.js:313:12)\n    at Function.Module.runMain (module.js:467:10)\n    at startup (node.js:136:18)\n    at node.js:963:3"
}

.pretty([options])

Parameters:

• options (object):
  • timeTransOnly (boolean): if set to true, it will only covert the unix timestamp to ISO 8601 date format, and reserialize the JSON (equivalent to pino -t).
  • formatter (function): a custom function to format the line, is passed the JSON object as an argument and should return a string value.

Example:

'use strict'

var pino = require('pino')
var pretty = pino.pretty()
pretty.pipe(process.stdout)
var log = pino({
  name: 'app',
  safe: true
}, pretty)

log.child({ widget: 'foo' }).info('hello')
log.child({ widget: 'bar' }).warn('hello 2')

Discussion:

Provides access to the CLI log prettifier as an API.

.addLevel(name, lvl)

Defines a new level for new logger instances. Returns true on success and false if there was a conflict (level name or number already exists).

Example:

var pino = require('pino')
pino.addLevel('myLevel', 35)
var log = pino({level: 'myLevel'})
log.myLevel('a message')