Catalyst

Section: User Contributed Perl Documentation (3)
Updated: 2021-02-08
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NAME

Log::Log4perl::Catalyst - Log::Log4perl Catalyst Module

SYNOPSIS

In your main Catalyst application module:

  use Log::Log4perl::Catalyst;

    # Either make Log4perl act like the Catalyst default logger:
  __PACKAGE__->log(Log::Log4perl::Catalyst->new());

    # or use a Log4perl configuration file, utilizing the full 
    # functionality of Log4perl
  __PACKAGE__->log(Log::Log4perl::Catalyst->new('l4p.conf'));

... and then sprinkle logging statements all over any code executed by Catalyst:

    $c->log->debug("This is using log4perl!");

DESCRIPTION

This module provides Log4perl functions to Catalyst applications. It was inspired by Catalyst::Log::Log4perl on CPAN, but has been completely rewritten and uses a different approach to unite Catalyst and Log4perl.

Log4perl provides loggers, usually associated with the current package, which can then be remote-controlled by a central configuration. This means that if you have a controller function like

    package MyApp::Controller::User;

    sub add : Chained('base'): PathPart('add'): Args(0) {
        my ( $self, $c ) = @_;

        $c->log->info("Adding a user");
        # ...
    }

Level-based control is available via the following methods:

   $c->log->debug("Reading configuration");
   $c->log->info("Adding a user");
   $c->log->warn("Can't read configuration ($!)");
   $c->log->error("Can't add user ", $user);
   $c->log->fatal("Database down, aborting request");

But that's not all, Log4perl is much more powerful.

The logging statement can be suppressed or activated based on a Log4perl file that looks like

      # All MyApp loggers opened up for DEBUG and above
    log4perl.logger.MyApp = DEBUG, Screen
    # ...

      # All loggers block messages below INFO
    log4perl.logger=INFO, Screen
    # ...

respectively. See the Log4perl manpage on how to perform fine-grained log-level and location filtering, and how to forward messages not only to the screen or to log files, but also to databases, email appenders, and much more.

Also, you can change the message layout. For example if you want to know where a particular statement was logged, turn on file names and line numbers:

    # Log4perl configuration file
    # ...
    log4perl.appender.Screen.layout.ConversionPattern = \
          %F{1}-%L: %p %m%n

Messages will then look like

    MyApp.pm-1869: INFO Saving user profile for user "wonko"

Or want to log a request's IP address with every log statement? No problem with Log4perl, just call

    Log::Log4perl::MDC->put( "ip", $c->req->address() );

at the beginning of the request cycle and use

    # Log4perl configuration file
    # ...
    log4perl.appender.Screen.layout.ConversionPattern = \
          [%d]-%X{ip} %F{1}-%L: %p %m%n

as a Log4perl layout. Messages will look like

    [2010/02/22 23:25:55]-123.122.108.10 MyApp.pm-1953: INFO Reading profile for user "wonko"

Again, check the Log4perl manual page, there's a plethora of configuration options.

METHODS

new($config, [%options])

If called without parameters, new() initializes Log4perl in a way so that messages are logged similarly to Catalyst's default logging mechanism. If you provide a configuration, either the name of a configuration file or a reference to a scalar string containing the configuration, it will call Log4perl with these parameters.

The second (optional) parameter is a list of key/value pairs:

  'autoflush'   =>  1   # Log without buffering ('abort' not supported)
  'watch_delay' => 30   # If set, use L<Log::Log4perl>'s init_and_watch

_flush()

Flushes the cache.

abort($abort)

Clears the logging system's internal buffers without logging anything.

Using :easy Macros with Catalyst

If you're tired of typing

    $c->log->debug("...");

and would prefer to use Log4perl's convenient :easy mode macros like

    DEBUG "...";

then just pull those macros in via Log::Log4perl's :easy mode and start cranking:

    use Log::Log4perl qw(:easy);

      # ... use macros later on
    sub base :Chained('/') :PathPart('apples') :CaptureArgs(0) {
        my ( $self, $c ) = @_;

        DEBUG "Handling apples";
    }

Note the difference between Log4perl's initialization in Catalyst, which uses the Catalyst-specific Log::Log4perl::Catalyst module (top of this page), and making use of Log4perl's loggers with the standard Log::Log4perl loggers and macros. While initialization requires Log4perl to perform dark magic to conform to Catalyst's different logging strategy, obtaining Log4perl's logger objects or calling its macros are unchanged.

Instead of using Catalyst's way of referencing the ``context'' object $c to obtain logger references via its log() method, you can just as well use Log4perl's get_logger() or macros to access Log4perl's logger singletons. The result is the same.

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

AUTHOR

Please contribute patches to the project on Github:

    http://github.com/mschilli/log4perl

Send bug reports or requests for enhancements to the authors via our

MAILING LIST (questions, bug reports, suggestions/patches): log4perl-devel@lists.sourceforge.net

Authors (please contact them via the list above, not directly): Mike Schilli <m@perlmeister.com>, Kevin Goess <cpan@goess.org>

Contributors (in alphabetical order): Ateeq Altaf, Cory Bennett, Jens Berthold, Jeremy Bopp, Hutton Davidson, Chris R. Donnelly, Matisse Enzer, Hugh Esco, Anthony Foiani, James FitzGibbon, Carl Franks, Dennis Gregorovic, Andy Grundman, Paul Harrington, Alexander Hartmaier David Hull, Robert Jacobson, Jason Kohles, Jeff Macdonald, Markus Peter, Brett Rann, Peter Rabbitson, Erik Selberg, Aaron Straup Cope, Lars Thegler, David Viner, Mac Yang.