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package Catmandu::Fix::rdf_ldf_statements;
use Catmandu::Sane;
use Moo;
use RDF::LDF;
use Catmandu::Fix::Has;
has path => (fix_arg => 1);
has subject => (fix_opt => 1, default => sub { undef });
has predicate => (fix_opt => 1, default => sub { undef });
has url => (fix_opt => 1, default => sub { undef });
has client => (is => 'lazy');
with 'Catmandu::Fix::SimpleGetValue';
sub _build_client {
my ($self) = @_;
my $url = $self->url // 'http://data.linkeddatafragments.org/viaf';
RDF::LDF->new(url => $url);
}
sub emit_value {
my ($self,$var,$fixer) = @_;
my $subject_var = $fixer->capture($self->subject);
my $predicate_var = $fixer->capture($self->predicate);
my $client_var = $fixer->capture($self->client);
my $it = $fixer->generate_var;
my $st = $fixer->generate_var;
my $perl = <<EOF;
if (is_value(${var})) {
my ${it} = ${client_var}->get_statements(${subject_var},${predicate_var},${var});
if (${it}) {
${var} = [];
while (my ${st} = ${it}->()) {
push \@{${var}} , ${st}->subject->uri;
}
}
}
EOF
$perl;
}
=head1 NAME
Catmandu::Fix::rdf_ldf_statements - lookup an object into a LDF endpoint
=head1 SYNOPSIS
# Replace a name with an array of matching VIAF records
# name: "\"Einstein, Albert, 1879-1955\""
rdf_ldf_statements(name,url:"http://data.linkedatafragments.org/viaf",predicate:"http://schema.org/alternateName")
# name:
# - http://viaf.org/viaf/75121530
=head1 DESCRIPTION
This L<Catmandu::Fix> can be used to find at a Linked Data Fragments endpoint
all subject URIs for which the object has a specific value found at a path. E.g.
rdf_ldf_statements(name,url:"http://data.linkedatafragments.org/viaf")
means, search at the endpoint http://data.linkedatafragments.org/viaf all the
subjects for which the object is the value found in 'name', and replace the name value
with all the found subjects.
=head1 ARGUMENTS
=over
=item subject
Optional subject URI to be used in the LDF query
=item predicate
Optional predicate URI to be used in the LDF query
=item url
Required URL to the Linked Data Fragments endpoint
=back
=head1 SEE ALSO
L<Catmandu::Fix>
=cut
1;
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