@eclipse-emfcloud/model-logger

Model Logger

This module provides a flexible logging factory that allows both default console logging and custom logging implementations.

Default behavior

The logger outputs messages to the console by default. To use the logger, import the getLogger function and create a logger instance with an optional name:

import { getLogger } from '@eclipse-emfcloud/model-logger';

export class AddressBook {
  // Retrieve the logger
  logger = getLogger('AddressBook');

  addAddress = (newAddress: Address): boolean => {
    const addresses = this.getAddressBook();

    if (!addresses.find((address) => compareAddresses(address, newAddress))) {
      logger.debug('Adding a new address');
      // [AddressBook]: Adding a new address
      addresses.push(newAddress);
      return true;
    } else {
      logger.error('Trying to add an existing address');
      // [AddressBook]: Trying to add an existing address
    }

    return false;
  };
}

The logger supports five log levels similar to the standard Console interface methods: log, error, debug, warn and info.

Override behavior

You can override the default logging behavior to implement custom logging strategies, such as logging to both console and file system.

To customize the logger, override the LOGGER_FACTORY.getLogger method with your implementation:

// index.ts
import * as fs from 'fs';
import path from 'path';
import { LOGGER_FACTORY } from '@eclipse-emfcloud/model-logger';

const logFilePath = path.resolve(__dirname, 'logs.txt');

// User-specific logger
LOGGER_FACTORY.getLogger = (name?: string) => ({
  error: (...messages: unknown[]) => {
    console.error(name ? `${name}:` : '', ...messages);
    fs.appendFileSync(
      logFilePath,
      `[error${name ? ` - ${name}:` : ''}]: ${messages.join(' ')}\n`
    );
  },
  warn: (...messages: unknown[]) => {
    console.warn(name ? `${name}:` : '', ...messages);
    fs.appendFileSync(
      logFilePath,
      `[warn${name ? ` - ${name}:` : ''}]: ${messages.join(' ')}\n`
    );
  },
  info: (...messages: unknown[]) => {
    console.info(name ? `${name}:` : '', ...messages);
    fs.appendFileSync(
      logFilePath,
      `[info${name ? ` - ${name}:` : ''}]: ${messages.join(' ')}\n`
    );
  },
  log: (...messages: unknown[]) => {
    console.log(name ? `${name}:` : '', ...messages);
    fs.appendFileSync(
      logFilePath,
      `[log${name ? ` - ${name}:` : ''}]: ${messages.join(' ')}\n`
    );
  },
  debug: (...messages: unknown[]) => {
    console.debug(name ? `${name}:` : '', ...messages);
    fs.appendFileSync(
      logFilePath,
      `[debug${name ? ` - ${name}:` : ''}]: ${messages.join(' ')}\n`
    );
  },
});

After overriding the factory, all subsequent calls to getLogger() will return your custom implementation while maintaining the named logger functionality.