ApiQueryLinks.php

Go to the documentation of this file.

<?php
use MediaWiki\Cache\LinkBatchFactory;
use MediaWiki\Linker\LinksMigration;
use MediaWiki\ParamValidator\TypeDef\NamespaceDef;
use MediaWiki\Title\Title;
use Wikimedia\ParamValidator\ParamValidator;
use Wikimedia\ParamValidator\TypeDef\IntegerDef;
 
class ApiQueryLinks extends ApiQueryGeneratorBase {
 
    private const LINKS = 'links';
    private const TEMPLATES = 'templates';
 
    private $table, $prefix, $titlesParam, $helpUrl;
 
    private $linkBatchFactory;
 
    private $linksMigration;
 
    public function __construct(
        ApiQuery $query,
        $moduleName,
        LinkBatchFactory $linkBatchFactory,
        LinksMigration $linksMigration
    ) {
        switch ( $moduleName ) {
            case self::LINKS:
                $this->table = 'pagelinks';
                $this->prefix = 'pl';
                $this->titlesParam = 'titles';
                $this->helpUrl = 'https://www.mediawiki.org/wiki/Special:MyLanguage/API:Links';
                break;
            case self::TEMPLATES:
                $this->table = 'templatelinks';
                $this->prefix = 'tl';
                $this->titlesParam = 'templates';
                $this->helpUrl = 'https://www.mediawiki.org/wiki/Special:MyLanguage/API:Templates';
                break;
            default:
                ApiBase::dieDebug( __METHOD__, 'Unknown module name' );
        }
 
        parent::__construct( $query, $moduleName, $this->prefix );
        $this->linkBatchFactory = $linkBatchFactory;
        $this->linksMigration = $linksMigration;
    }
 
    public function execute() {
        $this->run();
    }
 
    public function getCacheMode( $params ) {
        return 'public';
    }
 
    public function executeGenerator( $resultPageSet ) {
        $this->run( $resultPageSet );
    }
 
    private function run( $resultPageSet = null ) {
        $pages = $this->getPageSet()->getGoodPages();
        if ( $pages === [] ) {
            return; // nothing to do
        }
 
        $params = $this->extractRequestParams();
 
        if ( isset( $this->linksMigration::$mapping[$this->table] ) ) {
            [ $nsField, $titleField ] = $this->linksMigration->getTitleFields( $this->table );
            $queryInfo = $this->linksMigration->getQueryInfo( $this->table );
            $this->addTables( $queryInfo['tables'] );
            $this->addJoinConds( $queryInfo['joins'] );
        } else {
            $this->addTables( $this->table );
            $nsField = $this->prefix . '_namespace';
            $titleField = $this->prefix . '_title';
        }
 
        $this->addFields( [
            'pl_from' => $this->prefix . '_from',
            'pl_namespace' => $nsField,
            'pl_title' => $titleField,
        ] );
 
        $this->addWhereFld( $this->prefix . '_from', array_keys( $pages ) );
 
        $multiNS = true;
        $multiTitle = true;
        if ( $params[$this->titlesParam] ) {
            // Filter the titles in PHP so our ORDER BY bug avoidance below works right.
            $filterNS = $params['namespace'] ? array_fill_keys( $params['namespace'], true ) : false;
 
            $lb = $this->linkBatchFactory->newLinkBatch();
            foreach ( $params[$this->titlesParam] as $t ) {
                $title = Title::newFromText( $t );
                if ( !$title || $title->isExternal() ) {
                    $this->addWarning( [ 'apiwarn-invalidtitle', wfEscapeWikiText( $t ) ] );
                } elseif ( !$filterNS || isset( $filterNS[$title->getNamespace()] ) ) {
                    $lb->addObj( $title );
                }
            }
            $cond = $lb->constructSet( $this->prefix, $this->getDB() );
            if ( $cond ) {
                $this->addWhere( $cond );
                $multiNS = count( $lb->data ) !== 1;
                $multiTitle = count( array_merge( ...$lb->data ) ) !== 1;
            } else {
                // No titles so no results
                return;
            }
        } elseif ( $params['namespace'] ) {
            $this->addWhereFld( $nsField, $params['namespace'] );
            $multiNS = $params['namespace'] === null || count( $params['namespace'] ) !== 1;
        }
 
        if ( $params['continue'] !== null ) {
            $db = $this->getDB();
            $cont = $this->parseContinueParamOrDie( $params['continue'], [ 'int', 'int', 'string' ] );
            $op = $params['dir'] == 'descending' ? '<=' : '>=';
            $this->addWhere( $db->buildComparison( $op, [
                "{$this->prefix}_from" => $cont[0],
                $nsField => $cont[1],
                $titleField => $cont[2],
            ] ) );
        }
 
        $sort = ( $params['dir'] == 'descending' ? ' DESC' : '' );
        // Here's some MySQL craziness going on: if you use WHERE foo='bar'
        // and later ORDER BY foo MySQL doesn't notice the ORDER BY is pointless
        // but instead goes and filesorts, because the index for foo was used
        // already. To work around this, we drop constant fields in the WHERE
        // clause from the ORDER BY clause
        $order = [];
        if ( count( $pages ) !== 1 ) {
            $order[] = $this->prefix . '_from' . $sort;
        }
        if ( $multiNS ) {
            $order[] = $nsField . $sort;
        }
        if ( $multiTitle ) {
            $order[] = $titleField . $sort;
        }
        if ( $order ) {
            $this->addOption( 'ORDER BY', $order );
        }
        $this->addOption( 'LIMIT', $params['limit'] + 1 );
 
        $res = $this->select( __METHOD__ );
 
        if ( $resultPageSet === null ) {
            $this->executeGenderCacheFromResultWrapper( $res, __METHOD__, 'pl' );
 
            $count = 0;
            foreach ( $res as $row ) {
                if ( ++$count > $params['limit'] ) {
                    // We've reached the one extra which shows that
                    // there are additional pages to be had. Stop here...
                    $this->setContinueEnumParameter( 'continue',
                        "{$row->pl_from}|{$row->pl_namespace}|{$row->pl_title}" );
                    break;
                }
                $vals = [];
                ApiQueryBase::addTitleInfo( $vals, Title::makeTitle( $row->pl_namespace, $row->pl_title ) );
                $fit = $this->addPageSubItem( $row->pl_from, $vals );
                if ( !$fit ) {
                    $this->setContinueEnumParameter( 'continue',
                        "{$row->pl_from}|{$row->pl_namespace}|{$row->pl_title}" );
                    break;
                }
            }
        } else {
            $titles = [];
            $count = 0;
            foreach ( $res as $row ) {
                if ( ++$count > $params['limit'] ) {
                    // We've reached the one extra which shows that
                    // there are additional pages to be had. Stop here...
                    $this->setContinueEnumParameter( 'continue',
                        "{$row->pl_from}|{$row->pl_namespace}|{$row->pl_title}" );
                    break;
                }
                $titles[] = Title::makeTitle( $row->pl_namespace, $row->pl_title );
            }
            $resultPageSet->populateFromTitles( $titles );
        }
    }
 
    public function getAllowedParams() {
        return [
            'namespace' => [
                ParamValidator::PARAM_TYPE => 'namespace',
                ParamValidator::PARAM_ISMULTI => true,
                NamespaceDef::PARAM_EXTRA_NAMESPACES => [ NS_MEDIA, NS_SPECIAL ],
            ],
            'limit' => [
                ParamValidator::PARAM_DEFAULT => 10,
                ParamValidator::PARAM_TYPE => 'limit',
                IntegerDef::PARAM_MIN => 1,
                IntegerDef::PARAM_MAX => ApiBase::LIMIT_BIG1,
                IntegerDef::PARAM_MAX2 => ApiBase::LIMIT_BIG2
            ],
            'continue' => [
                ApiBase::PARAM_HELP_MSG => 'api-help-param-continue',
            ],
            $this->titlesParam => [
                ParamValidator::PARAM_ISMULTI => true,
            ],
            'dir' => [
                ParamValidator::PARAM_DEFAULT => 'ascending',
                ParamValidator::PARAM_TYPE => [
                    'ascending',
                    'descending'
                ]
            ],
        ];
    }
 
    protected function getExamplesMessages() {
        $name = $this->getModuleName();
        $path = $this->getModulePath();
 
        return [
            "action=query&prop={$name}&titles=Main%20Page"
                => "apihelp-{$path}-example-simple",
            "action=query&generator={$name}&titles=Main%20Page&prop=info"
                => "apihelp-{$path}-example-generator",
            "action=query&prop={$name}&titles=Main%20Page&{$this->prefix}namespace=2|10"
                => "apihelp-{$path}-example-namespaces",
        ];
    }
 
    public function getHelpUrls() {
        return $this->helpUrl;
    }
}