ApiQueryRandom.php

Go to the documentation of this file.

<?php

class ApiQueryRandom extends ApiQueryGeneratorBase {
    public function __construct( ApiQuery $query, $moduleName ) {
        parent::__construct( $query, $moduleName, 'rn' );
    }

    public function execute() {
        $this->run();
    }

    public function executeGenerator( $resultPageSet ) {
        $this->run( $resultPageSet );
    }

    protected function runQuery( $resultPageSet, $limit, $start, $startId, $end ) {
        $params = $this->extractRequestParams();

        $this->resetQueryParams();
        $this->addTables( 'page' );
        $this->addFields( [ 'page_id', 'page_random' ] );
        if ( is_null( $resultPageSet ) ) {
            $this->addFields( [ 'page_title', 'page_namespace' ] );
        } else {
            $this->addFields( $resultPageSet->getPageTableFields() );
        }
        $this->addWhereFld( 'page_namespace', $params['namespace'] );
        if ( $params['redirect'] || $params['filterredir'] === 'redirects' ) {
            $this->addWhereFld( 'page_is_redirect', 1 );
        } elseif ( $params['filterredir'] === 'nonredirects' ) {
            $this->addWhereFld( 'page_is_redirect', 0 );
        } elseif ( is_null( $resultPageSet ) ) {
            $this->addFields( [ 'page_is_redirect' ] );
        }
        $this->addOption( 'LIMIT', $limit + 1 );

        if ( $start !== null ) {
            $start = $this->getDB()->addQuotes( $start );
            if ( $startId !== null ) {
                $startId = (int)$startId;
                $this->addWhere( "page_random = $start AND page_id >= $startId OR page_random > $start" );
            } else {
                $this->addWhere( "page_random >= $start" );
            }
        }
        if ( $end !== null ) {
            $this->addWhere( 'page_random < ' . $this->getDB()->addQuotes( $end ) );
        }
        $this->addOption( 'ORDER BY', [ 'page_random', 'page_id' ] );

        $result = $this->getResult();
        $path = [ 'query', $this->getModuleName() ];

        $res = $this->select( __METHOD__ );
        $count = 0;
        foreach ( $res as $row ) {
            if ( $count++ >= $limit ) {
                return [ 0, "{$row->page_random}|{$row->page_id}" ];
            }
            if ( is_null( $resultPageSet ) ) {
                $title = Title::makeTitle( $row->page_namespace, $row->page_title );
                $page = [
                    'id' => (int)$row->page_id,
                ];
                ApiQueryBase::addTitleInfo( $page, $title );
                if ( isset( $row->page_is_redirect ) ) {
                    $page['redirect'] = (bool)$row->page_is_redirect;
                }
                $fit = $result->addValue( $path, null, $page );
                if ( !$fit ) {
                    return [ 0, "{$row->page_random}|{$row->page_id}" ];
                }
            } else {
                $resultPageSet->processDbRow( $row );
            }
        }

        return [ $limit - $count, null ];
    }

    public function run( $resultPageSet = null ) {
        $params = $this->extractRequestParams();

        // Since 'filterredir" will always be set in $params, we have to dig
        // into the WebRequest to see if it was actually passed.
        $request = $this->getMain()->getRequest();
        if ( $request->getCheck( $this->encodeParamName( 'filterredir' ) ) ) {
            $this->requireMaxOneParameter( $params, 'filterredir', 'redirect' );
        }

        if ( isset( $params['continue'] ) ) {
            $cont = explode( '|', $params['continue'] );
            $this->dieContinueUsageIf( count( $cont ) != 4 );
            $rand = $cont[0];
            $start = $cont[1];
            $startId = (int)$cont[2];
            $end = $cont[3] ? $rand : null;
            $this->dieContinueUsageIf( !preg_match( '/^0\.\d+$/', $rand ) );
            $this->dieContinueUsageIf( !preg_match( '/^0\.\d+$/', $start ) );
            $this->dieContinueUsageIf( $cont[2] !== (string)$startId );
            $this->dieContinueUsageIf( $cont[3] !== '0' && $cont[3] !== '1' );
        } else {
            $rand = wfRandom();
            $start = $rand;
            $startId = null;
            $end = null;
        }

        list( $left, $continue ) =
            $this->runQuery( $resultPageSet, $params['limit'], $start, $startId, $end );
        if ( $end === null && $continue === null ) {
            // Wrap around. We do this even if $left === 0 for continuation
            // (saving a DB query in this rare case probably isn't worth the
            // added code complexity it would require).
            $end = $rand;
            list( $left, $continue ) = $this->runQuery( $resultPageSet, $left, null, null, $end );
        }

        if ( $continue !== null ) {
            $endFlag = $end === null ? 0 : 1;
            $this->setContinueEnumParameter( 'continue', "$rand|$continue|$endFlag" );
        }

        if ( is_null( $resultPageSet ) ) {
            $this->getResult()->addIndexedTagName( [ 'query', $this->getModuleName() ], 'page' );
        }
    }

    public function getCacheMode( $params ) {
        return 'public';
    }

    public function getAllowedParams() {
        return [
            'namespace' => [
                ApiBase::PARAM_TYPE => 'namespace',
                ApiBase::PARAM_ISMULTI => true
            ],
            'filterredir' => [
                ApiBase::PARAM_TYPE => [ 'all', 'redirects', 'nonredirects' ],
                ApiBase::PARAM_DFLT => 'nonredirects', // for BC
            ],
            'redirect' => [
                ApiBase::PARAM_DEPRECATED => true,
                ApiBase::PARAM_DFLT => false,
            ],
            'limit' => [
                ApiBase::PARAM_TYPE => 'limit',
                ApiBase::PARAM_DFLT => 1,
                ApiBase::PARAM_MIN => 1,
                ApiBase::PARAM_MAX => ApiBase::LIMIT_BIG1,
                ApiBase::PARAM_MAX2 => ApiBase::LIMIT_BIG2
            ],
            'continue' => [
                ApiBase::PARAM_HELP_MSG => 'api-help-param-continue'
            ],
        ];
    }

    protected function getExamplesMessages() {
        return [
            'action=query&list=random&rnnamespace=0&rnlimit=2'
                => 'apihelp-query+random-example-simple',
            'action=query&generator=random&grnnamespace=0&grnlimit=2&prop=info'
                => 'apihelp-query+random-example-generator',
        ];
    }

    public function getHelpUrls() {
        return 'https://www.mediawiki.org/wiki/API:Random';
    }
}