David Golden
and 6 contributors


Metabase::Fact::Hash - fact subtype for simple hashes


version 0.024


  # defining the fact class
  package MyComment;
  use Metabase::Fact::Hash;
  our @ISA = qw/Metabase::Fact::Hash/;

  sub required_keys { qw/poster/ }

  sub optional_keys { qw/comment/ }

  sub content_metadata {
    my $self = shift;
    return {
      poster => [ '//str' => $self->content->{poster} ],

  sub validate_content {
    my $self = shift;
    $self->SUPER::validate_content; # required and optional keys

    # other analysis of values

...and then...

  # using the fact class
  my $fact = MyFact->new(
    resource => 'RJBS/Metabase-Fact-0.001.tar.gz',
    content => {
      poster  => 'larry',
      comment => 'Metabase rocks!',



Many (if not most) facts to be stored in a Metabase are just hashes of simple data. Metabase::Fact::Hash is a subclass of Metabase::Fact with most of the required Fact methods already implemented. If you write your class as a subclass of Metabase::Fact::Hash, you can store simple hashes in it.

You should implement required_keys and/or optional_keys as shown in the SYNOPSIS. The superclass valiate_content will ensure that required keys exist and that only required an optional keys exist. You may wish to subclass validate_content to validate the specific content of the hash given to the constructor.

You may wish to implement a content_metadata method to generate metadata about the hash contents.


Arguments provided to new



The canonical resource (URI) the Fact relates to. For CPAN distributions, this would be a cpan:///distfile/ URL. (See URI::cpan.)



A reference to the actual information associated with the fact. The exact form of the content is up to each Fact class to determine.


For information on the methods provided by this class, see Metabase::Fact.


Please report any bugs or feature using the CPAN Request Tracker. Bugs can be submitted through the web interface at http://rt.cpan.org/Dist/Display.html?Queue=Metabase-Fact

When submitting a bug or request, please include a test file or a patch to an existing test-file that illustrates the bug or desired feature.


  • David Golden <dagolden@cpan.org>

  • Ricardo Signes <rjbs@cpan.org>

  • H.Merijn Brand <hmbrand@cpan.org>


This software is Copyright (c) 2014 by David Golden.

This is free software, licensed under:

  The Apache License, Version 2.0, January 2004