My question is the following: I want to use a subroutine to construct an array when I call the new() method to create an object using perl Moo. Please see the following example.
package Customer;
use DBI;
use 5.010;
use Data::Dumper;
use Moo;
use FindBin qw/$Bin/;
use lib "$Bin/../../../lib";
use lib '/home/fm/lib';
use TT::SQL;
has id => (
is=>'ro',
required=>1,
);
has type => (
is=>'ro',
);
has emails => (
is=>'rw',
isa => sub {getEmails() },
);
sub getEmails
{
#connecting into de DB
my $self=shift;
my $db2 = TT::SQL::get_handler("xxxxxx","xxxxx");
my $fmuser=$self->id;
my $type=$self->type;
my $query;
#checking the customer type to perform the query
if ($type eq "xxxxxxxxxx")
{
$query=xxxxxxxxxxxxxx;
}
else
{
$query=xxxxxxxxxxxxxx;
}
my $ref = $db2->execute($query,$fmuser);
my @emails;
#retrieving emails
while ( my $row = $ref->fetchrow_hashref ) {
@emails=(@emails,"$row->{email}\n");
}
return @emails;
}
1;
Basically, I'm trying to retrieve some emails from a database, and do not worry about the queries and the DB access because when I execute the following:
my $cc= Customer->new(id=>92,type=>'xxxxxxx');
@emails=$cc->getEmails();
The result in @emails is the expected. However, when I execute:
my $cc= Customer->new(id=>92,type=>'xxxxxxx');
@emails=$cc->emails;
I do not even have a result.
I'll be very grateful if I get an answer to this question. Thanks in advance guys.
You want to use either a builder method or a default, isa is for enforcing type constraints:
default:
has emails => (
is => 'rw',
default => sub {
my ($self) = @_;
return $self->getEmails();
},
);
builder:
has emails => (
is => 'rw',
builder => '_build_emails',
);
sub build_emails {
my ($self) = @_;
return $self->getEmails();
}
If the getEmails()
subroutine requires any addition startup time (e.g Getting a handle to the database) I would also suggest adding the lazy => 1
argument to your emails attribute. This will only initialize it if it called.