includes/api/ApiQueryRandom.php

   1 <?php
   2
   3 /**
   4  * API for MediaWiki 1.8+
   5  *
   6  * Created on Monday, January 28, 2008
   7  *
   8  * Copyright © 2008 Brent Garber
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License along
  21  * with this program; if not, write to the Free Software Foundation, Inc.,
  22  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  23  * http://www.gnu.org/copyleft/gpl.html
  24  *
  25  * @file
  26  */
  27
  28 if ( !defined( 'MEDIAWIKI' ) ) {
  29         // Eclipse helper - will be ignored in production
  30         require_once( 'ApiQueryBase.php' );
  31 }
  32
  33 /**
  34  * Query module to get list of random pages
  35  *
  36  * @ingroup API
  37  */
  38
  39  class ApiQueryRandom extends ApiQueryGeneratorBase {
  40
  41         public function __construct( $query, $moduleName ) {
  42                 parent::__construct( $query, $moduleName, 'rn' );
  43         }
  44
  45         public function execute() {
  46                 $this->run();
  47         }
  48
  49         public function executeGenerator( $resultPageSet ) {
  50                 $this->run( $resultPageSet );
  51         }
  52
  53         protected function prepareQuery( $randstr, $limit, $namespace, &$resultPageSet, $redirect ) {
  54                 $this->resetQueryParams();
  55                 $this->addTables( 'page' );
  56                 $this->addOption( 'LIMIT', $limit );
  57                 $this->addWhereFld( 'page_namespace', $namespace );
  58                 $this->addWhereRange( 'page_random', 'newer', $randstr, null );
  59                 $this->addWhereFld( 'page_is_redirect', $redirect );
  60                 $this->addOption( 'USE INDEX', 'page_random' );
  61                 if ( is_null( $resultPageSet ) ) {
  62                         $this->addFields( array( 'page_id', 'page_title', 'page_namespace' ) );
  63                 } else {
  64                         $this->addFields( $resultPageSet->getPageTableFields() );
  65                 }
  66         }
  67
  68         protected function runQuery( &$resultPageSet ) {
  69                 $res = $this->select( __METHOD__ );
  70                 $count = 0;
  71                 foreach ( $res as $row ) {
  72                         $count++;
  73                         if ( is_null( $resultPageSet ) ) {
  74                                 // Prevent duplicates
  75                                 if ( !in_array( $row->page_id, $this->pageIDs ) ) {
  76                                         $fit = $this->getResult()->addValue(
  77                                                         array( 'query', $this->getModuleName() ),
  78                                                         null, $this->extractRowInfo( $row ) );
  79                                         if ( !$fit ) {
  80                                                 // We can't really query-continue a random list.
  81                                                 // Return an insanely high value so
  82                                                 // $count < $limit is false
  83                                                 return 1E9;
  84                                         }
  85                                         $this->pageIDs[] = $row->page_id;
  86                                 }
  87                         } else {
  88                                 $resultPageSet->processDbRow( $row );
  89                         }
  90                 }
  91
  92                 return $count;
  93         }
  94
  95         public function run( $resultPageSet = null ) {
  96                 $params = $this->extractRequestParams();
  97                 $result = $this->getResult();
  98                 $this->pageIDs = array();
  99
 100                 $this->prepareQuery( wfRandom(), $params['limit'], $params['namespace'], $resultPageSet, $params['redirect'] );
 101                 $count = $this->runQuery( $resultPageSet );
 102                 if ( $count < $params['limit'] ) {
 103                         /* We got too few pages, we probably picked a high value
 104                          * for page_random. We'll just take the lowest ones, see
 105                          * also the comment in Title::getRandomTitle()
 106                          */
 107                         $this->prepareQuery( 0, $params['limit'] - $count, $params['namespace'], $resultPageSet, $params['redirect'] );
 108                         $this->runQuery( $resultPageSet );
 109                 }
 110
 111                 if ( is_null( $resultPageSet ) ) {
 112                         $result->setIndexedTagName_internal( array( 'query', $this->getModuleName() ), 'page' );
 113                 }
 114         }
 115
 116         private function extractRowInfo( $row ) {
 117                 $title = Title::makeTitle( $row->page_namespace, $row->page_title );
 118                 $vals = array();
 119                 $vals['id'] = intval( $row->page_id );
 120                 ApiQueryBase::addTitleInfo( $vals, $title );
 121                 return $vals;
 122         }
 123
 124         public function getCacheMode( $params ) {
 125                 return 'public';
 126         }
 127
 128         public function getAllowedParams() {
 129                 return array(
 130                         'namespace' => array(
 131                                 ApiBase::PARAM_TYPE => 'namespace',
 132                                 ApiBase::PARAM_ISMULTI => true
 133                         ),
 134                         'limit' => array(
 135                                 ApiBase::PARAM_TYPE => 'limit',
 136                                 ApiBase::PARAM_DFLT => 1,
 137                                 ApiBase::PARAM_MIN => 1,
 138                                 ApiBase::PARAM_MAX => 10,
 139                                 ApiBase::PARAM_MAX2 => 20
 140                         ),
 141                         'redirect' => false,
 142                 );
 143         }
 144
 145         public function getParamDescription() {
 146                 return array(
 147                         'namespace' => 'Return pages in these namespaces only',
 148                         'limit' => 'Limit how many random pages will be returned',
 149                         'redirect' => 'Load a random redirect instead of a random page'
 150                 );
 151         }
 152
 153         public function getDescription() {
 154                 return array(
 155                         'Get a set of random pages',
 156                         '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 ',
 157                         '      random page on your list, "List of fictional monkeys" will *always* be second, "List of people on stamps of Vanuatu" third, etc',
 158                         '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'
 159                 );
 160         }
 161
 162         protected function getExamples() {
 163                 return 'api.php?action=query&list=random&rnnamespace=0&rnlimit=2';
 164         }
 165
 166         public function getVersion() {
 167                 return __CLASS__ . ': $Id: ApiQueryRandom.php overlordq$';
 168         }
 169 }