git.r.bdr.sh - rbdr/cologne/blob - lib/loggers/file.js

   1 'use strict';
   2
   3 const Fs = require('fs');
   4 const Utilities = require('../utilities');
   5
   6 /**
   7  * Logger for files.
   8  *
   9  * @memberof Loggers
  10  * @implements ILogger
  11  * @class File
  12  */
  13 module.exports = class FileLogger {
  14   constructor(config) {
  15
  16     /**
  17      * Path to the file it will write to, must be readable.
  18      *
  19      * @name file
  20      * @instance
  21      * @memberof Loggers.File
  22      * @type string
  23      * @default null
  24      */
  25     this.file = null;
  26
  27     /**
  28      * The formatter it will use to output the log. If not present it
  29      * will output raw JSON
  30      *
  31      * @name formatter
  32      * @instance
  33      * @memberof Loggers.File
  34      * @type IFormatter
  35      * @default null
  36      */
  37     this.formatter = null;
  38
  39     Object.assign(this, config);
  40
  41     this._stream = Fs.createWriteStream(this.file, { flags: 'a' });
  42   }
  43
  44   /**
  45    * Main entry point, for each incoming argument it will attempt to
  46    * format and send to the stream to be written.
  47    *
  48    * @function log
  49    * @instance
  50    * @memberof Loggers.File
  51    * @return {undefined}
  52    */
  53   log(...logs) {
  54
  55     for (const log of logs) {
  56       this._stream.write(this._format(log) + '\n');
  57     }
  58   }
  59
  60   _format(logObject) {
  61
  62     if (this.formatter) {
  63       return this.formatter.format(logObject);
  64     }
  65
  66     return Utilities.stringify(logObject);
  67   }
  68 };