G'day Moosers,
I'm writing a piece of code where I'm making use of the Maybe[DateTime]
construct. An event may not have occurred (in which case we want undef), or
it may have (in which case we want a DateTime object). I'm sucking in a
hunk of XML which represents the dates, and I have code that can convert a
hunk of XML (represented in a hash structure) into a DateTime object or undef:
use Moose::Util::TypeConstraints;
use DateTime;
use DateTime::Format::Natural;
class_type 'DateTime';
coerce 'Maybe[DateTime]' => from 'HashRef' => via {
warn "\n\n\n*** COERCING DATETIME ***\n\n\n";
if ($_->{nil} eq "true") { return undef; }
return DateTime::Format::Natural->new->parse_datetime($_->{content})
};
When trying to run this code, Moose is sad that it doesn't know about the
Maybe[DateTime] type:
Cannot find type 'Maybe[DateTime]', perhaps you forgot to load it at
/usr/lib/perl5/site_perl/5.10/Moose/Util/TypeConstraints.pm line 506
If I simply try to coerce DateTime, then I can't legitimately return undef,
because that fails the type constraint. If I declare `class_type
'Maybe[DateTime]'` then the coerce code runs, but Moose still complains that
the type constraint fails:
Attribute (last_blog_post_at) does not pass the type constraint because:
Validation failed for 'Maybe[DateTime]' failed with value undef (not isa
Maybe[DateTime]) at
/usr/lib/perl5/site_perl/5.10/Moose/Meta/Attribute.pm line 753
FWIW, the attribute in question looks like this:
has last_blog_post_at => ( isa => 'Maybe[DateTime]', coerce => 1 );
I'm using Moose 0.87.
Any advice would be appreciated.
Many thanks,
Paul
--
Paul Fenwick <[email protected]> | http://perltraining.com.au/
Director of Training | Ph: +61 3 9354 6001
Perl Training Australia | Fax: +61 3 9354 2681
