/ 
Mixin-Historian-0.101350
River stage zero No dependents
/ Mixin::Historian

NAME

Mixin::Historian - a mixin for recording history about objects

VERSION

version 0.101350

SYNOPSIS

package My::Object;
use Mixin::Historian -history => {
  driver => {
    class => 'YourDriver',
    ...,
  },
};

# Later...
my $object = My::Object->retrieve(1234);

$object->add_history({
  type     => 'lava damage',
  severity => 'very badly burned',
  volcano  => 'Eyjafjallajokull',
});

DESCRIPTION

Mixin::Historian is an application of Mixin::ExtraFields. If you're not familiar with it, you should read about it, both in its documentation and in this article about Mixin::ExtraFields.

Generally, it provides simple mechanism for write-only history. Importing the -history group will get you the add_history method, which generally will accept one hashref with at least a type key. This will be passed along to the driver's add_history method.

TODO

I have shoehorned an extra layer of functionality into the Historian driver that I use in my employer's code. When initialized, the Historian mixin is told all legal types, something like this:

type_map => {
  'lava damage' => {
    severity => { required => 1, store_as => 'extra_1' },
    volcano  => { required => 0, store_as => 'extra_2' },
  },
  ...
}

This way, history entries can be validated before writing. The store_as entries indicate how the arguments to add_history are mapped to database columns. The entire argument is also stored in one field as JSON, and a few other attributes are always required (like by_whom) and some are added just in time (like logged_at).

This feature is not yet present in the CPAN library because I have not yet found a suitable decomposition of concerns to make it a component.

AUTHOR

Ricardo Signes <rjbs@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2010 by Ricardo Signes.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.