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';
        }
}