includes/api/ApiQueryRandom.php

   1 <?php
   2
   3 /**
   4  *
   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 /**
  29  * Query module to get list of random pages
  30  *
  31  * @ingroup API
  32  */
  33
  34 class ApiQueryRandom extends ApiQueryGeneratorBase {
  35
  36         public function __construct( $query, $moduleName ) {
  37                 parent::__construct( $query, $moduleName, 'rn' );
  38         }
  39
  40         public function execute() {
  41                 $this->run();
  42         }
  43
  44         public function executeGenerator( $resultPageSet ) {
  45                 $this->run( $resultPageSet );
  46         }
  47
  48         /**
  49          * @param  $randstr
  50          * @param  $limit
  51          * @param  $namespace
  52          * @param $resultPageSet ApiPageSet
  53          * @param  $redirect
  54          * @return void
  55          */
  56         protected function prepareQuery( $randstr, $limit, $namespace, &$resultPageSet, $redirect ) {
  57                 $this->resetQueryParams();
  58                 $this->addTables( 'page' );
  59                 $this->addOption( 'LIMIT', $limit );
  60                 $this->addWhereFld( 'page_namespace', $namespace );
  61                 $this->addWhereRange( 'page_random', 'newer', $randstr, null );
  62                 $this->addWhereFld( 'page_is_redirect', $redirect );
  63                 $this->addOption( 'USE INDEX', 'page_random' );
  64                 if ( is_null( $resultPageSet ) ) {
  65                         $this->addFields( array( 'page_id', 'page_title', 'page_namespace' ) );
  66                 } else {
  67                         $this->addFields( $resultPageSet->getPageTableFields() );
  68                 }
  69         }
  70
  71         /**
  72          * @param $resultPageSet ApiPageSet
  73          * @return int
  74          */
  75         protected function runQuery( $resultPageSet = null ) {
  76                 $res = $this->select( __METHOD__ );
  77                 $count = 0;
  78                 foreach ( $res as $row ) {
  79                         $count++;
  80                         if ( is_null( $resultPageSet ) ) {
  81                                 // Prevent duplicates
  82                                 if ( !in_array( $row->page_id, $this->pageIDs ) ) {
  83                                         $fit = $this->getResult()->addValue(
  84                                                         array( 'query', $this->getModuleName() ),
  85                                                         null, $this->extractRowInfo( $row ) );
  86                                         if ( !$fit ) {
  87                                                 // We can't really query-continue a random list.
  88                                                 // Return an insanely high value so
  89                                                 // $count < $limit is false
  90                                                 return 1E9;
  91                                         }
  92                                         $this->pageIDs[] = $row->page_id;
  93                                 }
  94                         } else {
  95                                 $resultPageSet->processDbRow( $row );
  96                         }
  97                 }
  98
  99                 return $count;
 100         }
 101
 102         /**
 103          * @param $resultPageSet ApiPageSet
 104          * @return void
 105          */
 106         public function run( $resultPageSet = null ) {
 107                 $params = $this->extractRequestParams();
 108                 $result = $this->getResult();
 109                 $this->pageIDs = array();
 110
 111                 $this->prepareQuery( wfRandom(), $params['limit'], $params['namespace'], $resultPageSet, $params['redirect'] );
 112                 $count = $this->runQuery( $resultPageSet );
 113                 if ( $count < $params['limit'] ) {
 114                         /* We got too few pages, we probably picked a high value
 115                          * for page_random. We'll just take the lowest ones, see
 116                          * also the comment in Title::getRandomTitle()
 117                          */
 118                         $this->prepareQuery( 0, $params['limit'] - $count, $params['namespace'], $resultPageSet, $params['redirect'] );
 119                         $this->runQuery( $resultPageSet );
 120                 }
 121
 122                 if ( is_null( $resultPageSet ) ) {
 123                         $result->setIndexedTagName_internal( array( 'query', $this->getModuleName() ), 'page' );
 124                 }
 125         }
 126
 127         private function extractRowInfo( $row ) {
 128                 $title = Title::makeTitle( $row->page_namespace, $row->page_title );
 129                 $vals = array();
 130                 $vals['id'] = intval( $row->page_id );
 131                 ApiQueryBase::addTitleInfo( $vals, $title );
 132                 return $vals;
 133         }
 134
 135         public function getCacheMode( $params ) {
 136                 return 'public';
 137         }
 138
 139         public function getAllowedParams() {
 140                 return array(
 141                         'namespace' => array(
 142                                 ApiBase::PARAM_TYPE => 'namespace',
 143                                 ApiBase::PARAM_ISMULTI => true
 144                         ),
 145                         'limit' => array(
 146                                 ApiBase::PARAM_TYPE => 'limit',
 147                                 ApiBase::PARAM_DFLT => 1,
 148                                 ApiBase::PARAM_MIN => 1,
 149                                 ApiBase::PARAM_MAX => 10,
 150                                 ApiBase::PARAM_MAX2 => 20
 151                         ),
 152                         'redirect' => false,
 153                 );
 154         }
 155
 156         public function getParamDescription() {
 157                 return array(
 158                         'namespace' => 'Return pages in these namespaces only',
 159                         'limit' => 'Limit how many random pages will be returned',
 160                         'redirect' => 'Load a random redirect instead of a random page'
 161                 );
 162         }
 163
 164         public function getDescription() {
 165                 return array(
 166                         'Get a set of random pages',
 167                         '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 ',
 168                         '      random page on your list, "List of fictional monkeys" will *always* be second, "List of people on stamps of Vanuatu" third, etc',
 169                         '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'
 170                 );
 171         }
 172
 173         public function getExamples() {
 174                 return 'api.php?action=query&list=random&rnnamespace=0&rnlimit=2';
 175         }
 176
 177         public function getVersion() {
 178                 return __CLASS__ . ': $Id: ApiQueryRandom.php overlordq$';
 179         }
 180 }