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#!/usr/bin/env perl
use strict;
use warnings;
use lib qw(lib);
use File::Spec;
use URI::file;
use RDF::Query;
unless (@ARGV) {
print STDERR <<"END";
USAGE: $0 query.rq data.rdf [ data2.rdf ... ]
Reads in a SPARQL query from query.rq, and RDF/XML data from the data.rdf files.
The SPARQL query is executed against a triplestore containing data from the
data files, and query results are printed to standard output.
END
exit;
}
# get the query file from the arguments array
my $query_file = shift(@ARGV);
#open the query file and read in the query
my $sparql = do { local($/) = undef; open(my $fh, '<:utf8', $query_file); <$fh> };
# construct the query object
my $query = RDF::Query->new( $sparql );
unless ($query) {
# the query couldn't be constructed. print out the reason why.
warn RDF::Query->error;
exit;
}
# read in the list of files with RDF/XML content for querying
my @files = map { File::Spec->rel2abs( $_ ) } @ARGV;
# create a temporary triplestore, and wrap it into a model
my $store = RDF::Trine::Store::DBI->temporary_store();
my $model = RDF::Trine::Model->new( $store );
# create a rdf/xml parser object that we'll use to read in the rdf data
my $parser = RDF::Trine::Parser->new('rdfxml');
# loop over all the files
foreach my $i (0 .. $#files) {
my $file = $files[ $i ];
# $uri is the URI object used as the base uri for parsing
my $uri = URI::file->new_abs( $file );
my $content = do { open( my $fh, '<', $file ); local($/) = undef; <$fh> };
$parser->parse_into_model( $uri, $content, $model );
}
# execute the query against data contained in the model
my $iter = $query->execute( $model );
# print the results as a string to standard output
print $iter->as_string;
### or, if you want to iterator over each result row:
# while (my $s = $iter->next) {
# print $s . "\n";
# }
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