SparqlClient.php

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<?php
namespace MediaWiki\Sparql;
 
use Http;
use MediaWiki\Http\HttpRequestFactory;
 
class SparqlClient {
 
    const MAX_GET_SIZE = 2048;
 
    private $userAgent;
 
    private $timeout = 30;
 
    private $endpoint;
 
    private $options = [];
 
    private $requestFactory;
 
    public function __construct( $url, HttpRequestFactory $requestFactory ) {
        $this->endpoint = $url;
        $this->requestFactory = $requestFactory;
        $this->userAgent = Http::userAgent() . " SparqlClient";
    }
 
    public function setTimeout( $timeout ) {
        if ( $timeout >= 0 ) {
            $this->timeout = $timeout;
        }
        return $this;
    }
 
    public function setClientOptions( $options ) {
        $this->options = $options;
        return $this;
    }
 
    public function getUserAgent() {
        return $this->userAgent;
    }
 
    public function setUserAgent( $agent ) {
        $this->userAgent = $agent;
    }
 
    public function appendUserAgent( $agent ) {
        $this->userAgent .= ' ' . $agent;
    }
 
    public function query( $sparql, $rawData = false ) {
        if ( empty( $this->endpoint ) ) {
            throw new SparqlException( 'Endpoint URL can not be empty' );
        }
        $queryData = [ "query" => $sparql, "format" => "json" ];
        $options = array_merge( [ 'method' => 'GET' ], $this->options );
 
        if ( empty( $options['userAgent'] ) ) {
            $options['userAgent'] = $this->userAgent;
        }
 
        if ( $this->timeout >= 0 ) {
            // Blazegraph setting, see https://wiki.blazegraph.com/wiki/index.php/REST_API
            $queryData['maxQueryTimeMillis'] = $this->timeout * 1000;
            $options['timeout'] = $this->timeout;
        }
 
        if ( strlen( $sparql ) > self::MAX_GET_SIZE ) {
            // big requests go to POST
            $options['method'] = 'POST';
            $options['postData'] = 'query=' . urlencode( $sparql );
            unset( $queryData['query'] );
        }
 
        $url = wfAppendQuery( $this->endpoint, $queryData );
        $request = $this->requestFactory->create( $url, $options, __METHOD__ );
 
        $status = $request->execute();
 
        if ( !$status->isOK() ) {
            throw new SparqlException( "HTTP error: {$status->getWikiText()}" );
        }
        $result = $request->getContent();
        \Wikimedia\suppressWarnings();
        $data = json_decode( $result, true );
        \Wikimedia\restoreWarnings();
        if ( $data === null || $data === false ) {
            throw new SparqlException( "HTTP request failed, response:\n" .
                substr( $result, 1024 ) );
        }
 
        return $this->extractData( $data, $rawData );
    }
 
    private function extractData( $data, $rawData = false ) {
        $result = [];
        if ( $data && !empty( $data['results'] ) ) {
            $vars = $data['head']['vars'];
            $resrow = [];
            foreach ( $data['results']['bindings'] as $row ) {
                foreach ( $vars as $var ) {
                    if ( !isset( $row[$var] ) ) {
                        $resrow[$var] = null;
                        continue;
                    }
                    if ( $rawData ) {
                        $resrow[$var] = $row[$var];
                    } else {
                        $resrow[$var] = $row[$var]['value'];
                    }
                }
                $result[] = $resrow;
            }
        }
        return $result;
    }
 
}