ApiQueryRandom.php

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<?php

class ApiQueryRandom extends ApiQueryGeneratorBase {

    private $pageIDs;

    public function __construct( $query, $moduleName ) {
        parent::__construct( $query, $moduleName, 'rn' );
    }

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

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

    protected function prepareQuery( $randstr, $limit, $namespace, &$resultPageSet, $redirect ) {
        $this->resetQueryParams();
        $this->addTables( 'page' );
        $this->addOption( 'LIMIT', $limit );
        $this->addWhereFld( 'page_namespace', $namespace );
        $this->addWhereRange( 'page_random', 'newer', $randstr, null );
        $this->addWhereFld( 'page_is_redirect', $redirect );
        $this->addOption( 'USE INDEX', 'page_random' );
        if ( is_null( $resultPageSet ) ) {
            $this->addFields( array( 'page_id', 'page_title', 'page_namespace' ) );
        } else {
            $this->addFields( $resultPageSet->getPageTableFields() );
        }
    }

    protected function runQuery( $resultPageSet = null ) {
        $res = $this->select( __METHOD__ );
        $count = 0;
        foreach ( $res as $row ) {
            $count++;
            if ( is_null( $resultPageSet ) ) {
                // Prevent duplicates
                if ( !in_array( $row->page_id, $this->pageIDs ) ) {
                    $fit = $this->getResult()->addValue(
                            array( 'query', $this->getModuleName() ),
                            null, $this->extractRowInfo( $row ) );
                    if ( !$fit ) {
                        // We can't really query-continue a random list.
                        // Return an insanely high value so
                        // $count < $limit is false
                        return 1E9;
                    }
                    $this->pageIDs[] = $row->page_id;
                }
            } else {
                $resultPageSet->processDbRow( $row );
            }
        }

        return $count;
    }

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

        $this->prepareQuery( wfRandom(), $params['limit'], $params['namespace'], $resultPageSet, $params['redirect'] );
        $count = $this->runQuery( $resultPageSet );
        if ( $count < $params['limit'] ) {
            /* We got too few pages, we probably picked a high value
             * for page_random. We'll just take the lowest ones, see
             * also the comment in Title::getRandomTitle()
             */
            $this->prepareQuery( 0, $params['limit'] - $count, $params['namespace'], $resultPageSet, $params['redirect'] );
            $this->runQuery( $resultPageSet );
        }

        if ( is_null( $resultPageSet ) ) {
            $result->setIndexedTagName_internal( array( 'query', $this->getModuleName() ), 'page' );
        }
    }

    private function extractRowInfo( $row ) {
        $title = Title::makeTitle( $row->page_namespace, $row->page_title );
        $vals = array();
        $vals['id'] = intval( $row->page_id );
        ApiQueryBase::addTitleInfo( $vals, $title );
        return $vals;
    }

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

    public function getAllowedParams() {
        return array(
            'namespace' => array(
                ApiBase::PARAM_TYPE => 'namespace',
                ApiBase::PARAM_ISMULTI => true
            ),
            'limit' => array(
                ApiBase::PARAM_TYPE => 'limit',
                ApiBase::PARAM_DFLT => 1,
                ApiBase::PARAM_MIN => 1,
                ApiBase::PARAM_MAX => 10,
                ApiBase::PARAM_MAX2 => 20
            ),
            'redirect' => false,
        );
    }

    public function getParamDescription() {
        return array(
            'namespace' => 'Return pages in these namespaces only',
            'limit' => 'Limit how many random pages will be returned',
            'redirect' => 'Load a random redirect instead of a random page'
        );
    }

    public function getResultProperties() {
        return array(
            '' => array(
                'id' => 'integer',
                'ns' => 'namespace',
                'title' => 'string'
            )
        );
    }

    public function getDescription() {
        return array(
            'Get a set of random pages',
            'NOTE: Pages are listed in a fixed sequence, only the starting point is random. This means that if, for example, "Main Page" is the first ',
            '      random page on your list, "List of fictional monkeys" will *always* be second, "List of people on stamps of Vanuatu" third, etc',
            'NOTE: If the number of pages in the namespace is lower than rnlimit, you will get fewer pages. You will not get the same page twice'
        );
    }

    public function getExamples() {
        return 'api.php?action=query&list=random&rnnamespace=0&rnlimit=2';
    }

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