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         private $pageIDs;
  37
  38         public function __construct( $query, $moduleName ) {
  39                 parent::__construct( $query, $moduleName, 'rn' );
  40         }
  41
  42         public function execute() {
  43                 $this->run();
  44         }
  45
  46         public function executeGenerator( $resultPageSet ) {
  47                 $this->run( $resultPageSet );
  48         }
  49
  50         /**
  51          * @param  $randstr
  52          * @param  $limit
  53          * @param  $namespace
  54          * @param $resultPageSet ApiPageSet
  55          * @param  $redirect
  56          * @return void
  57          */
  58         protected function prepareQuery( $randstr, $limit, $namespace, &$resultPageSet, $redirect ) {
  59                 $this->resetQueryParams();
  60                 $this->addTables( 'page' );
  61                 $this->addOption( 'LIMIT', $limit );
  62                 $this->addWhereFld( 'page_namespace', $namespace );
  63                 $this->addWhereRange( 'page_random', 'newer', $randstr, null );
  64                 $this->addWhereFld( 'page_is_redirect', $redirect );
  65                 $this->addOption( 'USE INDEX', 'page_random' );
  66                 if ( is_null( $resultPageSet ) ) {
  67                         $this->addFields( array( 'page_id', 'page_title', 'page_namespace' ) );
  68                 } else {
  69                         $this->addFields( $resultPageSet->getPageTableFields() );
  70                 }
  71         }
  72
  73         /**
  74          * @param $resultPageSet ApiPageSet
  75          * @return int
  76          */
  77         protected function runQuery( $resultPageSet = null ) {
  78                 $res = $this->select( __METHOD__ );
  79                 $count = 0;
  80                 foreach ( $res as $row ) {
  81                         $count++;
  82                         if ( is_null( $resultPageSet ) ) {
  83                                 // Prevent duplicates
  84                                 if ( !in_array( $row->page_id, $this->pageIDs ) ) {
  85                                         $fit = $this->getResult()->addValue(
  86                                                         array( 'query', $this->getModuleName() ),
  87                                                         null, $this->extractRowInfo( $row ) );
  88                                         if ( !$fit ) {
  89                                                 // We can't really query-continue a random list.
  90                                                 // Return an insanely high value so
  91                                                 // $count < $limit is false
  92                                                 return 1E9;
  93                                         }
  94                                         $this->pageIDs[] = $row->page_id;
  95                                 }
  96                         } else {
  97                                 $resultPageSet->processDbRow( $row );
  98                         }
  99                 }
 100
 101                 return $count;
 102         }
 103
 104         /**
 105          * @param $resultPageSet ApiPageSet
 106          * @return void
 107          */
 108         public function run( $resultPageSet = null ) {
 109                 $params = $this->extractRequestParams();
 110                 $result = $this->getResult();
 111                 $this->pageIDs = array();
 112
 113                 $this->prepareQuery( wfRandom(), $params['limit'], $params['namespace'], $resultPageSet, $params['redirect'] );
 114                 $count = $this->runQuery( $resultPageSet );
 115                 if ( $count < $params['limit'] ) {
 116                         /* We got too few pages, we probably picked a high value
 117                          * for page_random. We'll just take the lowest ones, see
 118                          * also the comment in Title::getRandomTitle()
 119                          */
 120                         $this->prepareQuery( 0, $params['limit'] - $count, $params['namespace'], $resultPageSet, $params['redirect'] );
 121                         $this->runQuery( $resultPageSet );
 122                 }
 123
 124                 if ( is_null( $resultPageSet ) ) {
 125                         $result->setIndexedTagName_internal( array( 'query', $this->getModuleName() ), 'page' );
 126                 }
 127         }
 128
 129         private function extractRowInfo( $row ) {
 130                 $title = Title::makeTitle( $row->page_namespace, $row->page_title );
 131                 $vals = array();
 132                 $vals['id'] = intval( $row->page_id );
 133                 ApiQueryBase::addTitleInfo( $vals, $title );
 134                 return $vals;
 135         }
 136
 137         public function getCacheMode( $params ) {
 138                 return 'public';
 139         }
 140
 141         public function getAllowedParams() {
 142                 return array(
 143                         'namespace' => array(
 144                                 ApiBase::PARAM_TYPE => 'namespace',
 145                                 ApiBase::PARAM_ISMULTI => true
 146                         ),
 147                         'limit' => array(
 148                                 ApiBase::PARAM_TYPE => 'limit',
 149                                 ApiBase::PARAM_DFLT => 1,
 150                                 ApiBase::PARAM_MIN => 1,
 151                                 ApiBase::PARAM_MAX => 10,
 152                                 ApiBase::PARAM_MAX2 => 20
 153                         ),
 154                         'redirect' => false,
 155                 );
 156         }
 157
 158         public function getParamDescription() {
 159                 return array(
 160                         'namespace' => 'Return pages in these namespaces only',
 161                         'limit' => 'Limit how many random pages will be returned',
 162                         'redirect' => 'Load a random redirect instead of a random page'
 163                 );
 164         }
 165
 166         public function getResultProperties() {
 167                 return array(
 168                         '' => array(
 169                                 'id' => 'integer',
 170                                 'ns' => 'namespace',
 171                                 'title' => 'string'
 172                         )
 173                 );
 174         }
 175
 176         public function getDescription() {
 177                 return array(
 178                         'Get a set of random pages',
 179                         '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 ',
 180                         '      random page on your list, "List of fictional monkeys" will *always* be second, "List of people on stamps of Vanuatu" third, etc',
 181                         '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'
 182                 );
 183         }
 184
 185         public function getExamples() {
 186                 return 'api.php?action=query&list=random&rnnamespace=0&rnlimit=2';
 187         }
 188 }