If you want to change all the default logging for that specific model, you can simply use User. logger = Logger. new(STDOUT) or wherever you want to log to. In the same way, ActiveRecord::Base.
In a Rails app, logs are stored under the /log folder.
Since the logger library comes with Ruby, there's no need to install any gems or other libraries. To begin using the logger library, simply require 'logger' and create a new Logger object. Any messages written to the Logger object will be written to the log file.
You can create a Logger object yourself from inside any model. Just pass the file name to the constructor and use the object like the usual Rails logger
:
class User < ActiveRecord::Base
def my_logger
@@my_logger ||= Logger.new("#{Rails.root}/log/my.log")
end
def before_save
my_logger.info("Creating user with name #{self.name}")
end
end
Here I used a class attribute to memoize the logger. This way it won't be created for every single User object that gets created, but you aren't required to do that. Remember also that you can inject the my_logger
method directly into the ActiveRecord::Base
class (or into some superclass of your own if you don't like to monkey patch too much) to share the code between your app's models.
Update
I made a gem based on the solution below, called multi_logger. Just do this in the initializer:
MultiLogger.add_logger('post')
and call
Rails.logger.post.error('hi')
# or call logger.post.error('hi') if it is accessible.
and you are done.
If you want to code it yourself, see below:
A more complete solution would be to place the following in your lib/
or config/initializers/
directory.
The benefit is that you can setup formatter to prefix timestamps or severity to the logs automatically. This is accessible from anywhere in Rails, and looks neater by using the singleton pattern.
# Custom Post logger
require 'singleton'
class PostLogger < Logger
include Singleton
def initialize
super(Rails.root.join('log/post_error.log'))
self.formatter = formatter()
self
end
# Optional, but good for prefixing timestamps automatically
def formatter
Proc.new{|severity, time, progname, msg|
formatted_severity = sprintf("%-5s",severity.to_s)
formatted_time = time.strftime("%Y-%m-%d %H:%M:%S")
"[#{formatted_severity} #{formatted_time} #{$$}] #{msg.to_s.strip}\n"
}
end
class << self
delegate :error, :debug, :fatal, :info, :warn, :add, :log, :to => :instance
end
end
PostLogger.error('hi')
# [ERROR 2012-09-12 10:40:15] hi
A decent option that works for me is to just add a fairly plain class to your app/models
folder such as app/models/my_log.rb
class MyLog
def self.debug(message=nil)
@my_log ||= Logger.new("#{Rails.root}/log/my.log")
@my_log.debug(message) unless message.nil?
end
end
then in your controller, or really almost anywhere that you could reference a model's class from within your rails app, i.e. anywhere you could do Post.create(:title => "Hello world", :contents => "Lorum ipsum");
or something similar you can log to your custom file like this
MyLog.debug "Hello world"
Define a logger class in (say) app/models/special_log.rb:
class SpecialLog
LogFile = Rails.root.join('log', 'special.log')
class << self
cattr_accessor :logger
delegate :debug, :info, :warn, :error, :fatal, :to => :logger
end
end
initialize the logger in (say) config/initializers/special_log.rb:
SpecialLog.logger = Logger.new(SpecialLog::LogFile)
SpecialLog.logger.level = 'debug' # could be debug, info, warn, error or fatal
Anywhere in your app, you can log with:
SpecialLog.debug("something went wrong")
# or
SpecialLog.info("life is good")
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