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.\" ========================================================================
.\"
.IX Title "Mojo::Log 3pm"
.TH Mojo::Log 3pm 2024-05-15 "perl v5.38.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
Mojo::Log \- Simple logger
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&  use Mojo::Log;
\&
\&  # Log to STDERR
\&  my $log = Mojo::Log\->new;
\&
\&  # Customize log file location and minimum log level
\&  my $log = Mojo::Log\->new(path => \*(Aq/var/log/mojo.log\*(Aq, level => \*(Aqwarn\*(Aq);
\&
\&  # Log messages
\&  $log\->trace(\*(AqDoing stuff\*(Aq);
\&  $log\->debug(\*(AqNot sure what is happening here\*(Aq);
\&  $log\->info(\*(AqFYI: it happened again\*(Aq);
\&  $log\->warn(\*(AqThis might be a problem\*(Aq);
\&  $log\->error(\*(AqGarden variety error\*(Aq);
\&  $log\->fatal(\*(AqBoom\*(Aq);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Mojo::Log is a simple logger for Mojo projects.
.SH EVENTS
.IX Header "EVENTS"
Mojo::Log inherits all events from Mojo::EventEmitter and can emit the following new ones.
.SS message
.IX Subsection "message"
.Vb 1
\&  $log\->on(message => sub ($log, $level, @lines) {...});
.Ve
.PP
Emitted when a new message gets logged.
.PP
.Vb 1
\&  $log\->on(message => sub ($log, $level, @lines) { say "$level: ", @lines });
.Ve
.SH ATTRIBUTES
.IX Header "ATTRIBUTES"
Mojo::Log implements the following attributes.
.SS color
.IX Subsection "color"
.Vb 2
\&  my $bool = $log\->color;
\&  $log     = $log\->color($bool);
.Ve
.PP
Colorize log messages with the levels \f(CW\*(C`warn\*(C'\fR, \f(CW\*(C`error\*(C'\fR and \f(CW\*(C`fatal\*(C'\fR using Term::ANSIColor, defaults to the value of
the \f(CW\*(C`MOJO_LOG_COLOR\*(C'\fR environment variables. Note that this attribute is \fBEXPERIMENTAL\fR and might change without
warning!
.SS format
.IX Subsection "format"
.Vb 2
\&  my $cb = $log\->format;
\&  $log   = $log\->format(sub {...});
.Ve
.PP
A callback for formatting log messages.
.PP
.Vb 1
\&  $log\->format(sub ($time, $level, @lines) { "[2018\-11\-08 14:20:13.77168] [28320] [info] I ♥ Mojolicious\en" });
.Ve
.SS handle
.IX Subsection "handle"
.Vb 2
\&  my $handle = $log\->handle;
\&  $log       = $log\->handle(IO::Handle\->new);
.Ve
.PP
Log filehandle used by default "message" event, defaults to opening "path" or \f(CW\*(C`STDERR\*(C'\fR.
.SS history
.IX Subsection "history"
.Vb 2
\&  my $history = $log\->history;
\&  $log        = $log\->history([[time, \*(Aqdebug\*(Aq, \*(AqThat went wrong\*(Aq]]);
.Ve
.PP
The last few logged messages.
.SS level
.IX Subsection "level"
.Vb 2
\&  my $level = $log\->level;
\&  $log      = $log\->level(\*(Aqdebug\*(Aq);
.Ve
.PP
Active log level, defaults to \f(CW\*(C`trace\*(C'\fR. Available log levels are \f(CW\*(C`trace\*(C'\fR, \f(CW\*(C`debug\*(C'\fR, \f(CW\*(C`info\*(C'\fR, \f(CW\*(C`warn\*(C'\fR, \f(CW\*(C`error\*(C'\fR and
\&\f(CW\*(C`fatal\*(C'\fR, in that order.
.SS max_history_size
.IX Subsection "max_history_size"
.Vb 2
\&  my $size = $log\->max_history_size;
\&  $log     = $log\->max_history_size(5);
.Ve
.PP
Maximum number of logged messages to store in "history", defaults to \f(CW10\fR.
.SS path
.IX Subsection "path"
.Vb 2
\&  my $path = $log\->path
\&  $log     = $log\->path(\*(Aq/var/log/mojo.log\*(Aq);
.Ve
.PP
Log file path used by "handle".
.SS short
.IX Subsection "short"
.Vb 2
\&  my $bool = $log\->short;
\&  $log     = $log\->short($bool);
.Ve
.PP
Generate short log messages without a timestamp but with journald log level prefix, suitable for systemd environments,
defaults to the value of the \f(CW\*(C`MOJO_LOG_SHORT\*(C'\fR environment variables.
.SH METHODS
.IX Header "METHODS"
Mojo::Log inherits all methods from Mojo::EventEmitter and implements the following new ones.
.SS append
.IX Subsection "append"
.Vb 1
\&  $log\->append("[2018\-11\-08 14:20:13.77168] [28320] [info] I ♥ Mojolicious\en");
.Ve
.PP
Append message to "handle".
.SS capture
.IX Subsection "capture"
.Vb 2
\&  my $messages = $log\->capture;
\&  my $messages = $log\->capture(\*(Aqdebug\*(Aq);
.Ve
.PP
Capture log messages for as long as the returned object exists, useful for testing log messages.
.PP
.Vb 7
\&  # Test your log messages
\&  my $messages = $log\->capture(\*(Aqtrace\*(Aq);
\&  $log\->fatal(\*(AqSomething very bad happened\*(Aq);
\&  $log\->trace(\*(AqJust some debug information\*(Aq);
\&  like $messages, qr/Something very bad happened/, \*(Aqlogs contain fatal message\*(Aq;
\&  like $messages\->[\-1], qr/Just some debug information/, \*(Aqtrace message was last\*(Aq;
\&  undef $messages;
.Ve
.SS context
.IX Subsection "context"
.Vb 1
\&  my $new = $log\->context(\*(Aq[extra]\*(Aq, \*(Aq[information]\*(Aq);
.Ve
.PP
Construct a new child Mojo::Log object that will include context information with every log message.
.PP
.Vb 5
\&  # Log with context
\&  my $log = Mojo::Log\->new;
\&  my $context = $log\->context(\*(Aq[17a60115]\*(Aq);
\&  $context\->debug(\*(AqThis is a log message with context information\*(Aq);
\&  $context\->info(\*(AqAnd another\*(Aq);
.Ve
.SS debug
.IX Subsection "debug"
.Vb 3
\&  $log = $log\->debug(\*(AqYou screwed up, but that is ok\*(Aq);
\&  $log = $log\->debug(\*(AqAll\*(Aq, \*(Aqcool\*(Aq);
\&  $log = $log\->debug(sub {...});
.Ve
.PP
Emit "message" event and log \f(CW\*(C`debug\*(C'\fR message.
.SS error
.IX Subsection "error"
.Vb 3
\&  $log = $log\->error(\*(AqYou really screwed up this time\*(Aq);
\&  $log = $log\->error(\*(AqWow\*(Aq, \*(Aqseriously\*(Aq);
\&  $log = $log\->error(sub {...});
.Ve
.PP
Emit "message" event and log \f(CW\*(C`error\*(C'\fR message.
.SS fatal
.IX Subsection "fatal"
.Vb 3
\&  $log = $log\->fatal(\*(AqIts over...\*(Aq);
\&  $log = $log\->fatal(\*(AqBye\*(Aq, \*(Aqbye\*(Aq);
\&  $log = $log\->fatal(sub {...});
.Ve
.PP
Emit "message" event and log \f(CW\*(C`fatal\*(C'\fR message.
.SS info
.IX Subsection "info"
.Vb 3
\&  $log = $log\->info(\*(AqYou are bad, but you prolly know already\*(Aq);
\&  $log = $log\->info(\*(AqOk\*(Aq, \*(Aqthen\*(Aq);
\&  $log = $log\->info(sub {...});
.Ve
.PP
Emit "message" event and log \f(CW\*(C`info\*(C'\fR message.
.SS is_level
.IX Subsection "is_level"
.Vb 1
\&  my $bool = $log\->is_level(\*(Aqdebug\*(Aq);
.Ve
.PP
Check active log "level".
.PP
.Vb 3
\&  # True
\&  $log\->level(\*(Aqdebug\*(Aq)\->is_level(\*(Aqdebug\*(Aq);
\&  $log\->level(\*(Aqdebug\*(Aq)\->is_level(\*(Aqinfo\*(Aq);
\&
\&  # False
\&  $log\->level(\*(Aqinfo\*(Aq)\->is_level(\*(Aqdebug\*(Aq);
\&  $log\->level(\*(Aqfatal\*(Aq)\->is_level(\*(Aqwarn\*(Aq);
.Ve
.SS new
.IX Subsection "new"
.Vb 3
\&  my $log = Mojo::Log\->new;
\&  my $log = Mojo::Log\->new(level => \*(Aqwarn\*(Aq);
\&  my $log = Mojo::Log\->new({level => \*(Aqwarn\*(Aq});
.Ve
.PP
Construct a new Mojo::Log object and subscribe to "message" event with default logger.
.SS trace
.IX Subsection "trace"
.Vb 3
\&  $log = $log\->trace(\*(AqWhatever\*(Aq);
\&  $log = $log\->trace(\*(AqWho\*(Aq, \*(Aqcares\*(Aq);
\&  $log = $log\->trace(sub {...});
.Ve
.PP
Emit "message" event and log \f(CW\*(C`trace\*(C'\fR message.
.SS warn
.IX Subsection "warn"
.Vb 3
\&  $log = $log\->warn(\*(AqDont do that Dave...\*(Aq);
\&  $log = $log\->warn(\*(AqNo\*(Aq, \*(Aqreally\*(Aq);
\&  $log = $log\->warn(sub {...});
.Ve
.PP
Emit "message" event and log \f(CW\*(C`warn\*(C'\fR message.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Mojolicious, Mojolicious::Guides, <https://mojolicious.org>.