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Week 7 - logutils gem - yet another (lightweight, simple) logging library in Ruby

Sooner or later you will debug your code and add some print statements to help you along. Example:

puts "[debug] value: #{value}"
puts "[debug] value.class.name: #{value.class.name}

A "better" way is to use a logger that lets you turn off and on your debug messages as needed and why not a add some more message classes for errors or warnings, for example?

The "classic" message class hierarchy reads:

  • [OFF]
  • FATAL
  • ERROR
  • WARN
  • INFO
  • DEBUG
  • [ALL]

What's the logutils gem?

Using the logutils gem - yet another logging library - you can print all messages and more. Start by getting a logger e.g.:

logger = LogUtils::Logger.new

And now you can use the "standard" methods such as #debug, #info, #warn, etc.

logger.debug "msg"
logger.info "another msg"
logger.warn "another msg"
logger.error "another msg"
logger.fatal "another msg"

To turn on/off debug messages or any others in the hierarchy use the level attribute. Example:

logger.level = :info

Will print only message of class info and above and, thus, turn off debug messages.

Logging Mixin

What else? For your convenience you can include the logging machinery in a Ruby class with a single line using the Logging mixin e.g.

include LogUtils::Logging

This will add/mixin the logger attribute reader e.g.

def logger
  @logger ||= Logger[ self ]
end

And you're all setup to start logging. Example:

class SampleClass

 include Logging

  def initialize
    logger.info 'Hello, SampleClass!'
  end
end

Bonus: Log to the database using LogDb

To log to the database use an addon, that is, the logutils-activerecord gem. Example:

require 'logutils'
require 'logutils/activerecord'   # Note: will also require 'active_record'

include LogUtils    # lets you use Logger instead of LogUtils::Logger

logger = Logger[ 'Test' ]
logger.info 'Hello, LogUtils!'

LOG_DB_CONFIG = {
  adapter:   'sqlite3',
  database:  ':memory:'
}

ActiveRecord::Base.establish_connection( LOG_DB_CONFIG )

LogDb.create   # create logs table
LogDb.setup    # setup handler that saves logs in the database

logger.info '¡Hola! LogUtils'
logger.warn 'Servus LogUtils!'

To create the logs table in the database use:

LogDb.create

Just a shortcut for:

create_table :logs do |t|
  t.string  :msg,   null: false
  t.string  :level, null: false  # e.g. fatal, error, warn, info, debug
  t.string  :app
  t.string  :tag
  t.integer :pid
  t.integer :tid, limit: 8
  t.string  :ts
  t.timestamps
end

To start logging to the database add a log event handler that stores log messages in the database. Use:

LogDb.setup

To dump all log messages to the console you can use the log model. Example:

LogDb::Model::Log.order('created_at DESC').each do |log|
  puts "[#{log.level}] #{log.msg}"
end

Will print:

[info] ¡Hola! LogUtils
[warn] Servus LogUtils!

That's it. Happy logging.

Find Out More

logutils

logutils-activerecord