I have a type constraint I've set up, called 'MyApp::DateOnly'. It's for a DateTime object with certain restrictions.

type 'MyApp::DateOnly' => as 'DateTime'
    => where {     blessed($_)
               &&  $_->isa('DateTime')
               &&  $_->hour == 0  &&  $_->min == 0  && $_->sec == 0
           };

[download]

I have also included a couple of simple coercions, so that the user can pass a properly-formatted string as a convenience, and so that DateTime objects are made to follow the limitations of the type:

coerce  'Search::DateOnly' => from 'DateTime'
    => via { $_->truncate(to => 'day') };

coerce  'Search::DateOnly' => from 'Str'
    => via
    {
        state $parser = DateTime::Format::Strptime->new(
                         pattern => '%Y/%m/%d');
        $parser->parse_datetime($_);
    };

[download]

This all works fine.

Now I need to allow undef as a null value for certain attributes. I thought I could set up such an attribute like this:

has foo => (
            is       => 'ro',
            isa      => 'Maybe[MyApp::DateOnly]',
            coerce   => 1,
           );

[download]

but it doesn't work -- not only does it fail on undef arguments, it won't even accept and coerce the Str or DateTime arguments it did before! Is Maybe[] processing not done automatically? How do I enable it for this type constraint?

In reply to Moose type question by Sue D. Nymme

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