NAME

Log::Any::Adapter::JSON - One-line JSON logging of arbitrary structured data

SYNOPSIS

Get a logger and specify the output destination:

use Log::Any '$log';
use Log::Any::Adapter ('JSON', '/path/to/file.log');

# or

use Log::Any '$log';
use Log::Any::Adapter;

my $handle = ...; # FH, pipe, etc

Log::Any::Adapter->set('JSON', $handle);

Log some data:

$log->info('Hello, world');
$log->info('Hello, %s', $name);
$log->debug('Blabla', { tracking_id => 42 });
$log->debug('Blorgle', { foo => 'bar' }, [qw/a b c/], 'last thing');

DESCRIPTION

This Log::Any adapter logs formatted messages and arbitrary structured data in a single line of JSON per entry. You must pass a filename or an open handle to which the entries will be printed.

Optionally you may pass an encoding argument which will be used to apply a binmode layer to the output handle. The default encoding is UTF-8.

OUTPUT

Logged data fields

The adapter expects a string and an optional list @items.

If the string has no formatting tokens, it is included in the log entry in the message field as-is.

If the string has formatting tokens, @items is checked to verify that the next N values are scalars, where N is the number of tokens in the string. If the number is the same, the string and tokens are combined using sprintf() and the resulting string is included in the log entry in the message field. If the token and value counts don't match, the adapter croaks.

After the format processing, the remainder of the items array is processed. It may hold arrayrefs, which are included in a top- level key named list_data; additional scalars, which are pushed into the additional_messages key; and hashrefs. The first hashref encountered has its keys promoted to top-level keys in the log entry, while additional hashrefs are included in a top-level key named hash_data.

Other fields

In addition, the log entry will have the following fields:

• time
• level
• category

EXAMPLES

Plain text message

$log->debug('a simple message');

Output is a single line with JSON like:

{
  "category":"main",
  "level":"debug",
  "message":"hello, world",
  "time":"2021-03-03T17:23:25.73124"
}

Formatted message

my $val = "string";
my $num = 2;

$log->debug('a formatted %s with %d tokens', $val, $num);

Output is a single line with JSON like:

{
  "category":"main",
  "level":"debug",
  "message":"a formatted string with 2 tokens",
  "time":"2021-03-03T17:23:25.73124"
}

Single hashref

The first hashref encountered has its keys elevated to the top level.

$log->debug('the message', { tracker => 42 });

Output is a single line with JSON like:

{
  "category":"main",
  "level":"debug",
  "message":"the message",
  "time":"2021-03-03T17:23:25.73124",
  "tracker":42
}

Reserved key names that may not be used in the first hashref include:

* category
* context
* level
* message
* time

Additional hashrefs and arrayrefs

$log->debug('the message', { tracker => 42 }, { foo => 'bar'});

Output is a single line with JSON like:

{
  "category":"main",
  "hash_data":{
    "foo":"bar"
  },
  "level":"debug",
  "message":"the message",
  "time":"2021-03-03T17:23:25.73124",
  "tracker":42
}

Another example:

$log->debug('the message', { tracker => 42 }, {foo => 'bar'}, [1..3]);

Output is a single line with JSON like:

{
  "category":"main",
  "hash_data":[
    {"foo":"bar"}
  ],
  "level":"debug",
  "list_data":[
    [1,2,3]
  ],
  "message":"the message",
  "time":"2021-03-03T17:23:25.73124",
  "tracker":42

}

Additional messages

Any scalars that are passed that are not consumed as the values of formatting tokens will be included in an additional_messages key.

$log->debug('a simple message', 'foo', 'bar');

Output is a single line with JSON like:

{
  "additional_messages":[
    'foo',
    'bar'
  ],
  "category":"main",
  "level":"debug",
  "message":"hello, world",
  "time":"2021-03-03T17:23:25.73124"
}

SEE ALSO

Log::Any

Log::Any::Adapter