Node File Logger

A simple logger for logging exceptions and error details in a log file.

``
_ _ _ _____ _ _ _
| \ | | ___ __| | ___ | ___(_) | ___ | | ___ __ _ __ _ ___ _ __
| \| |/ _ \ / _ |/ _ \ | |_ | | |/ _ \ | | / _ \ / _ |/ _ |/ _ \ '__|
| |\ | (_) | (_| | __/ | _| | | | __/ | |__| (_) | (_| | (_| | __/ |
|_| \_|\___/ \__,_|\___| |_| |_|_|\___| |_____\___/ \__, |\__, |\___|_|
|___/ |___/
``

Docs & Features

Dependencies

moment.js
moment-timezone.js
node-stringify.js

Suports all logging levels

- DEBUG: The DEBUG Level designates fine-grained informational events that are most useful to debug an application.
- TRACE: The TRACE Level designates finer-grained informational events than the DEBUG
- INFO: The INFO level designates informational messages that highlight the progress of the application at coarse-grained level.
- WARN: The WARN level designates potentially harmful situations.
- ERROR: The ERROR level designates error events that might still allow the application to continue running.
- FATAL: The FATAL level designates very severe error events that will presumably lead the application to abort.

Create date-wise log files

It has an option to create a new log file for the current date which will be named like YYYY-MM-DD-log.log

Extras

- Allows logging the service name & method name
- Allows logging a short error message and an entire error object (optional)
- Error objects are stringified and then logged to the log file

Has a callback

It allows you to run a callback after the logging process.

Steps to use

Installation

npm install node-file-logger --save

Create instance of Node file logger

`javascript
// Ceate an instance of node file logger
const log = require('node-file-logger');
log.SetUserOptions(options); // Options are optional
`

Using options

`javascript
// It is recommended to set options in a separate module and include it in the code
// Everything in the example below are default values
const options = {
timeZone: 'America/Los_Angeles',
folderPath: './logs/',
dateBasedFileNaming: true,
// Required only if dateBasedFileNaming is set to false
fileName: 'All_Logs',
// Required only if dateBasedFileNaming is set to true
fileNamePrefix: 'Logs_',
fileNameSuffix: '',
fileNameExtension: '.log',

dateFormat: 'YYYY-MM-DD',
timeFormat: 'HH:mm:ss.SSS',
logLevel: 'debug',
onlyFileLogging: true
}

// Note: If you set dateBasedFileNaming to false, then a log file will be created at the folder path with the provided fileName.
// If set to true then a logfile will be created with the name provided in the options

log.SetUserOptions(options);
`

Examples

Simple logging to a file with date-based log file naming

`javascript
const options = {
folderPath: './logs/',
dateBasedFileNaming: true,
fileNamePrefix: 'DailyLogs_',
fileNameExtension: '.log',
dateFormat: 'YYYY_MM_D',
timeFormat: 'h:mm:ss A',
}

const log = require('node-file-logger');
log.SetUserOptions(options);

// Log a simple error message
log.Info('Some informational log message');

// *
// Ouput in Logfile:
// File name : ./logs/Logs_2018_02_23.log
// 5:52:28 PM | Info | Some informational log message
// *

// Log an error message with service and method names
log.Error('Something has failed!', 'Some service', 'Some method');

// *
// Ouput in Logfile:
// File name : ./logs/Logs_2018_02_23.log
// 5:52:28 PM | Error | Service: Some service | Method: Some method | Some error message
// *

// Log an fatal error message with service and method names and error object
log.Fatal('Something has failed!', 'Some service', 'Some method', errorObj);

// *
// Ouput in Logfile:
// File name : ./logs/Logs_2018_02_23.log
// 5:52:28 PM | Fatal | Service: Some service | Method: Some method | Something is broken
{
unhandledException: Something serious has happened
}
// *

// Log an error message with callback
log.Info('Something has failed!', null, null, null, function() {
// Do something
});

`

Simple logging to a file without date-based file naming

`javascript
const options = {
folderPath: './logs/',
dateBasedFileNaming: false,
fileName: 'All_Logs.log',
dateFormat: 'YYYY_MM_D',
timeFormat: 'h:mm:ss A',
}

const log = require('node-file-logger');
log.SetUserOptions(options);

// Log a simple error message
log.Info('Some informational log message');


// *
// Ouput in Logfile:
// File name : ./logs/All_Logs.log
// 2018_02_23 5:52:28 PM | Info | Some informational log message
// *
``

API Reference

Methods:

$3

Sets user options for node file logger

| Parameter | Description | Datatype | Optional |
| --------- |-------------| ---------| -------- |
| object | _Configuration Object_ | object | no |

#### Details of the configuration object

| Parameter | Description | Datatype | Default Value |
| --------- |-------------| ---------| -------- |
| folderPath | _Path of the folder where log file will be saved_ | string | ./logs/ |
| dateBasedFileNaming | _If set to true, date based file naming standard will be followed for log file_ | boolean |true |
| fileName | _Needed in case of single log file, where dateBasedFileNaming is set to false_ | string | All_Logs |
| fileNamePrefix | _Log file name prefix_ | string | Logs_ |
| fileNameSuffix | _Log file name suffix_ | string | '' |
| fileNameExtension | _Log file name extension_ | string | .log |
| dateFormat | _Date format for timestamp logging_ | string | YYYY-MM-DD |
| timeFormat | _Time format for timestamp logging_ | string | HH:mm:ss.SSS |
| logLevel | _Allowed values - debug, prod, prod-trace (Details below)_ | string | debug |
| onlyFileLogging | _If set to false then messages are logged to console as well_ | boolean | true |

#### Details of log levels
'prod' and 'prod-trace' levels are suitable for production releases

| Log level name | Description |
| --------- |-------------|
| debug | All log level messages are logged |
| prod | Only 'warn', 'info', 'error' and 'fatal' messages are logged. 'debug' and 'trace' messages are not logged. |
| prod-trace | Only 'debug' messages are not logged. All the others are logged. |

$3

Logs a debug message in the log file

| Parameter | Description | Datatype | Optional |
| --------- |-------------| ---------| -------- |
| errorMessage | _Error message to be logged in the file_ | string | no |
| serviceName | _Service name from which info was logged_ | string | yes |
| methodName | _Method name from which info was logged_ | string | yes |
| errorObj | _Error object that needs to be logged_ | object | yes |
| callback | _Callback method that is called after error logging (may return an error)_ | function | yes |

$3

Logs a trace message in the log file

| Parameter | Description | Datatype | Optional |
| --------- |-------------| ---------| -------- |
| errorMessage | _Error message to be logged in the file_ | string | no |
| serviceName | _Service name from which info was logged_ | string | yes |
| methodName | _Method name from which info was logged_ | string | yes |
| errorObj | _Error object that needs to be logged_ | object | yes |
| callback | _Callback method that is called after error logging (may return an error)_ | function | yes |

$3

Logs a informational message in the log file

| Parameter | Description | Datatype | Optional |
| --------- |-------------| ---------| -------- |
| errorMessage | _Error message to be logged in the file_ | string | no |
| serviceName | _Service name from which info was logged_ | string | yes |
| methodName | _Method name from which info was logged_ | string | yes |
| errorObj | _Error object that needs to be logged_ | object | yes |
| callback | _Callback method that is called after error logging (may return an error)_ | function | yes |

$3

Logs a warning message in the log file

| Parameter | Description | Datatype | Optional |
| --------- |-------------| ---------| -------- |
| errorMessage | _Error message to be logged in the file_ | string | no |
| serviceName | _Service name from which info was logged_ | string | yes |
| methodName | _Method name from which info was logged_ | string | yes |
| errorObj | _Error object that needs to be logged_ | object | yes |
| callback | _Callback method that is called after error logging (may return an error)_ | function | yes |

$3

Logs a error message in the log file

| Parameter | Description | Datatype | Optional |
| --------- |-------------| ---------| -------- |
| errorMessage | _Error message to be logged in the file_ | string | no |
| serviceName | _Service name from which info was logged_ | string | yes |
| methodName | _Method name from which info was logged_ | string | yes |
| errorObj | _Error object that needs to be logged_ | object | yes |
| callback | _Callback method that is called after error logging (may return an error)_ | function | yes |

$3

Logs a fatal error message in the log file

| Parameter | Description | Datatype | Optional |
| --------- |-------------| ---------| -------- |
| errorMessage | _Error message to be logged in the file_ | string | no |
| serviceName | _Service name from which info was logged_ | string | yes |
| methodName | _Method name from which info was logged_ | string | yes |
| errorObj | _Error object that needs to be logged_ | object | yes |
| callback | _Callback method that is called after error logging (may return an error)_ | function | yes |

$3

Used to log any kind of log message in the log file (Custom Log level)

| Parameter | Description | Datatype | Optional |
| --------- |-------------| ---------| -------- |
| logLevel | _Log level - 'debug', 'trace', 'info', 'warn', 'error', 'fatal', on any custom log level _ | string | no |
| errorMessage | _Error message to be logged in the file_ | string | no |
| serviceName | _Service name from which info was logged_ | string | yes |
| methodName | _Method name from which info was logged_ | string | yes |
| errorObj | _Error object that needs to be logged_ | object | yes |
| callback | _Callback method that is called after error logging (may return an error)_ | function | yes |

License

Apache 2.0