ApiQueryLinks.php

Go to the documentation of this file.

<?php
class ApiQueryLinks extends ApiQueryGeneratorBase {

    const LINKS = 'links';
    const TEMPLATES = 'templates';

    private $table, $prefix, $description, $helpUrl;

    public function __construct( ApiQuery $query, $moduleName ) {
        switch ( $moduleName ) {
            case self::LINKS:
                $this->table = 'pagelinks';
                $this->prefix = 'pl';
                $this->description = 'link';
                $this->titlesParam = 'titles';
                $this->titlesParamDescription = 'Only list links to these titles. Useful ' .
                    'for checking whether a certain page links to a certain title.';
                $this->helpUrl = 'https://www.mediawiki.org/wiki/API:Properties#links_.2F_pl';
                break;
            case self::TEMPLATES:
                $this->table = 'templatelinks';
                $this->prefix = 'tl';
                $this->description = 'template';
                $this->titlesParam = 'templates';
                $this->titlesParamDescription = 'Only list these templates. Useful ' .
                    'for checking whether a certain page uses a certain template.';
                $this->helpUrl = 'https://www.mediawiki.org/wiki/API:Properties#templates_.2F_tl';
                break;
            default:
                ApiBase::dieDebug( __METHOD__, 'Unknown module name' );
        }

        parent::__construct( $query, $moduleName, $this->prefix );
    }

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

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

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

    private function run( $resultPageSet = null ) {
        if ( $this->getPageSet()->getGoodTitleCount() == 0 ) {
            return; // nothing to do
        }

        $params = $this->extractRequestParams();

        $this->addFields( array(
            'pl_from' => $this->prefix . '_from',
            'pl_namespace' => $this->prefix . '_namespace',
            'pl_title' => $this->prefix . '_title'
        ) );

        $this->addTables( $this->table );
        $this->addWhereFld( $this->prefix . '_from', array_keys( $this->getPageSet()->getGoodTitles() ) );
        $this->addWhereFld( $this->prefix . '_namespace', $params['namespace'] );

        if ( !is_null( $params[$this->titlesParam] ) ) {
            $lb = new LinkBatch;
            foreach ( $params[$this->titlesParam] as $t ) {
                $title = Title::newFromText( $t );
                if ( !$title ) {
                    $this->setWarning( "\"$t\" is not a valid title" );
                } else {
                    $lb->addObj( $title );
                }
            }
            $cond = $lb->constructSet( $this->prefix, $this->getDB() );
            if ( $cond ) {
                $this->addWhere( $cond );
            }
        }

        if ( !is_null( $params['continue'] ) ) {
            $cont = explode( '|', $params['continue'] );
            $this->dieContinueUsageIf( count( $cont ) != 3 );
            $op = $params['dir'] == 'descending' ? '<' : '>';
            $plfrom = intval( $cont[0] );
            $plns = intval( $cont[1] );
            $pltitle = $this->getDB()->addQuotes( $cont[2] );
            $this->addWhere(
                "{$this->prefix}_from $op $plfrom OR " .
                "({$this->prefix}_from = $plfrom AND " .
                "({$this->prefix}_namespace $op $plns OR " .
                "({$this->prefix}_namespace = $plns AND " .
                "{$this->prefix}_title $op= $pltitle)))"
            );
        }

        $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 = array();
        if ( count( $this->getPageSet()->getGoodTitles() ) != 1 ) {
            $order[] = $this->prefix . '_from' . $sort;
        }
        if ( count( $params['namespace'] ) != 1 ) {
            $order[] = $this->prefix . '_namespace' . $sort;
        }

        $order[] = $this->prefix . '_title' . $sort;
        $this->addOption( 'ORDER BY', $order );
        $this->addOption( 'USE INDEX', $this->prefix . '_from' );
        $this->addOption( 'LIMIT', $params['limit'] + 1 );

        $res = $this->select( __METHOD__ );

        if ( is_null( $resultPageSet ) ) {
            $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 = array();
                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 = array();
            $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 array(
            'namespace' => array(
                ApiBase::PARAM_TYPE => 'namespace',
                ApiBase::PARAM_ISMULTI => true
            ),
            'limit' => array(
                ApiBase::PARAM_DFLT => 10,
                ApiBase::PARAM_TYPE => 'limit',
                ApiBase::PARAM_MIN => 1,
                ApiBase::PARAM_MAX => ApiBase::LIMIT_BIG1,
                ApiBase::PARAM_MAX2 => ApiBase::LIMIT_BIG2
            ),
            'continue' => null,
            $this->titlesParam => array(
                ApiBase::PARAM_ISMULTI => true,
            ),
            'dir' => array(
                ApiBase::PARAM_DFLT => 'ascending',
                ApiBase::PARAM_TYPE => array(
                    'ascending',
                    'descending'
                )
            ),
        );
    }

    public function getParamDescription() {
        $desc = $this->description;

        return array(
            'namespace' => "Show {$desc}s in this namespace(s) only",
            'limit' => "How many {$desc}s to return",
            'continue' => 'When more results are available, use this to continue',
            $this->titlesParam => $this->titlesParamDescription,
            'dir' => 'The direction in which to list',
        );
    }

    public function getDescription() {
        return "Returns all {$this->description}s from the given page(s).";
    }

    public function getExamples() {
        $desc = $this->description;
        $name = $this->getModuleName();

        return array(
            "api.php?action=query&prop={$name}&titles=Main%20Page" => "Get {$desc}s from the [[Main Page]]",
            "api.php?action=query&generator={$name}&titles=Main%20Page&prop=info"
                => "Get information about the {$desc} pages in the [[Main Page]]",
            "api.php?action=query&prop={$name}&titles=Main%20Page&{$this->prefix}namespace=2|10"
                => "Get {$desc}s from the Main Page in the User and Template namespaces",
        );
    }

    public function getHelpUrls() {
        return $this->helpUrl;
    }
}