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package Catmandu::Exporter::RDF;
use namespace::clean;
use Catmandu::Sane;
use Moo;
use RDF::Trine::Serializer;
use RDF::Trine::Model;
use RDF::aREF;
our $VERSION = '0.32';
with 'Catmandu::RDF';
with 'Catmandu::Exporter';
# internal attributes
has decoder => (
is => 'lazy'
);
has serializer => (
is => 'lazy'
);
has model => (
is => 'lazy'
);
sub _build_decoder {
RDF::aREF::Decoder->new(
ns => $_[0]->ns // ($_[0]->ns eq 0 ? { } : RDF::NS->new),
callback => $_[0]->model
);
}
sub _build_serializer {
RDF::Trine::Serializer->new($_[0]->type // 'ntriples');
}
sub _build_model {
my $self = shift;
# Streaming output when we have type => NTriples
if (lc($self->type // 'ntriples') eq 'ntriples') {
sub {
require RDF::Trine::Statement;
eval {
my $st = RDF::aREF::Decoder::trine_statement(@_);
$self->fh->print($self->serializer->statement_as_string($st));
};
$self->decoder->error($@) if $@;
};
}
else {
RDF::Trine::Model->new;
}
}
sub add {
my ($self, $aref) = @_;
$self->decoder->decode($aref, keep_bnode_map => 1);
}
sub commit {
my ($self) = @_;
if (ref $self->model eq 'RDF::Trine::Model') {
$self->model->end_bulk_ops;
$self->decoder->clean_bnodes;
$self->serializer->serialize_model_to_file( $self->fh, $self->model );
}
}
1;
__END__
=head1 NAME
Catmandu::Exporter::RDF - serialize RDF data
=head1 SYNOPSIS
In Perl code:
use Catmandu -all;
my $exporter = exporter('RDF',
file => 'export.rdf',
type => 'XML',
fix => 'rdf.fix'
);
$exporter->add( $aref ); # pass RDF data in aREF encoding
$exporter->commit;
=head1 DESCRIPTION
This L<Catmandu::Exporter> exports RDF data in different RDF serializations.
=head1 CONFIGURATION
=over
=item file
=item fh
=item encoding
=item fix
Default configuration options of L<Catmandu::Exporter>. The option C<fix> is
supported as derived from L<Catmandu::Fixable>. For every C<add> or for every
item in C<add_many> the given fixes will be applied first.
=item type
A serialization form can be set with option C<type> with default value
C<NTriples>. The option must refer to a subclass of L<RDF::Trine::Serializer>,
for instance C<Turtle> for RDF/Turtle with L<RDF::Trine::Serializer::Turtle>.
The first letter is transformed uppercase, so C<< format => 'turtle' >> will
work as well. In addition there are aliases C<ttl> for C<Turtle>, C<n3> for
C<Notation3>, C<xml> and C<XML> for C<RDFXML>, C<json> for C<RDFJSON>.
When the option C<type> is set to 'NTriples' the export can be streamed in all
other cases the results are exported in bulk after C<commit()>.
=item ns
The option C<ns> can refer to an instance of or to a constructor argument of
L<RDF::NS>. Use a fixed date, such as "C<20130816>" to make sure your URI
namespace prefixes are stable.
=back
=head1 METHODS
See also L<Catmandu::Exporter>.
=head2 add( ... )
RDF data is added given in B<another RDF Encoding Form (aREF)> as
implemented with L<RDF::aREF> and defined at L<http://github.com/gbv/aref>.
=head2 count
Returns the number of times C<add> has been called. In contrast to other
Catmandu exporters, this does not reflect the number of exporter records
because RDF data is always merged to one RDF graph.
=head2 uri( $uri )
Expand and abbreviated with L<RDF::NS>. For instance "C<dc:title>" is expanded
to "C<http://purl.org/dc/elements/1.1/title>".
=cut
=head1 SEE ALSO
Serialization is based on L<RDF::Trine::Serializer>.
=encoding utf8
=cut
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