includes/api/ApiQuery.php

   1 <?php
   2 /**
   3  *
   4  *
   5  * Created on Sep 7, 2006
   6  *
   7  * Copyright © 2006 Yuri Astrakhan "<Firstname><Lastname>@gmail.com"
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write to the Free Software Foundation, Inc.,
  21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  22  * http://www.gnu.org/copyleft/gpl.html
  23  *
  24  * @file
  25  */
  26
  27 /**
  28  * This is the main query class. It behaves similar to ApiMain: based on the
  29  * parameters given, it will create a list of titles to work on (an ApiPageSet
  30  * object), instantiate and execute various property/list/meta modules, and
  31  * assemble all resulting data into a single ApiResult object.
  32  *
  33  * In generator mode, a generator will be executed first to populate a second
  34  * ApiPageSet object, and that object will be used for all subsequent modules.
  35  *
  36  * @ingroup API
  37  */
  38 class ApiQuery extends ApiBase {
  39
  40         /**
  41          * List of Api Query prop modules
  42          * @var array
  43          */
  44         private static $QueryPropModules = array(
  45                 'categories' => 'ApiQueryCategories',
  46                 'categoryinfo' => 'ApiQueryCategoryInfo',
  47                 'contributors' => 'ApiQueryContributors',
  48                 'deletedrevisions' => 'ApiQueryDeletedRevisions',
  49                 'duplicatefiles' => 'ApiQueryDuplicateFiles',
  50                 'extlinks' => 'ApiQueryExternalLinks',
  51                 'fileusage' => 'ApiQueryBacklinksprop',
  52                 'images' => 'ApiQueryImages',
  53                 'imageinfo' => 'ApiQueryImageInfo',
  54                 'info' => 'ApiQueryInfo',
  55                 'links' => 'ApiQueryLinks',
  56                 'linkshere' => 'ApiQueryBacklinksprop',
  57                 'iwlinks' => 'ApiQueryIWLinks',
  58                 'langlinks' => 'ApiQueryLangLinks',
  59                 'pageprops' => 'ApiQueryPageProps',
  60                 'redirects' => 'ApiQueryBacklinksprop',
  61                 'revisions' => 'ApiQueryRevisions',
  62                 'stashimageinfo' => 'ApiQueryStashImageInfo',
  63                 'templates' => 'ApiQueryLinks',
  64                 'transcludedin' => 'ApiQueryBacklinksprop',
  65         );
  66
  67         /**
  68          * List of Api Query list modules
  69          * @var array
  70          */
  71         private static $QueryListModules = array(
  72                 'allcategories' => 'ApiQueryAllCategories',
  73                 'alldeletedrevisions' => 'ApiQueryAllDeletedRevisions',
  74                 'allfileusages' => 'ApiQueryAllLinks',
  75                 'allimages' => 'ApiQueryAllImages',
  76                 'alllinks' => 'ApiQueryAllLinks',
  77                 'allpages' => 'ApiQueryAllPages',
  78                 'allredirects' => 'ApiQueryAllLinks',
  79                 'allrevisions' => 'ApiQueryAllRevisions',
  80                 'mystashedfiles' => 'ApiQueryMyStashedFiles',
  81                 'alltransclusions' => 'ApiQueryAllLinks',
  82                 'allusers' => 'ApiQueryAllUsers',
  83                 'backlinks' => 'ApiQueryBacklinks',
  84                 'blocks' => 'ApiQueryBlocks',
  85                 'categorymembers' => 'ApiQueryCategoryMembers',
  86                 'deletedrevs' => 'ApiQueryDeletedrevs',
  87                 'embeddedin' => 'ApiQueryBacklinks',
  88                 'exturlusage' => 'ApiQueryExtLinksUsage',
  89                 'filearchive' => 'ApiQueryFilearchive',
  90                 'imageusage' => 'ApiQueryBacklinks',
  91                 'iwbacklinks' => 'ApiQueryIWBacklinks',
  92                 'langbacklinks' => 'ApiQueryLangBacklinks',
  93                 'logevents' => 'ApiQueryLogEvents',
  94                 'pageswithprop' => 'ApiQueryPagesWithProp',
  95                 'pagepropnames' => 'ApiQueryPagePropNames',
  96                 'prefixsearch' => 'ApiQueryPrefixSearch',
  97                 'protectedtitles' => 'ApiQueryProtectedTitles',
  98                 'querypage' => 'ApiQueryQueryPage',
  99                 'random' => 'ApiQueryRandom',
 100                 'recentchanges' => 'ApiQueryRecentChanges',
 101                 'search' => 'ApiQuerySearch',
 102                 'tags' => 'ApiQueryTags',
 103                 'usercontribs' => 'ApiQueryContributions',
 104                 'users' => 'ApiQueryUsers',
 105                 'watchlist' => 'ApiQueryWatchlist',
 106                 'watchlistraw' => 'ApiQueryWatchlistRaw',
 107         );
 108
 109         /**
 110          * List of Api Query meta modules
 111          * @var array
 112          */
 113         private static $QueryMetaModules = array(
 114                 'allmessages' => 'ApiQueryAllMessages',
 115                 'siteinfo' => 'ApiQuerySiteinfo',
 116                 'userinfo' => 'ApiQueryUserInfo',
 117                 'filerepoinfo' => 'ApiQueryFileRepoInfo',
 118                 'tokens' => 'ApiQueryTokens',
 119         );
 120
 121         /**
 122          * @var ApiPageSet
 123          */
 124         private $mPageSet;
 125
 126         private $mParams;
 127         private $mNamedDB = array();
 128         private $mModuleMgr;
 129
 130         /**
 131          * @param ApiMain $main
 132          * @param string $action
 133          */
 134         public function __construct( ApiMain $main, $action ) {
 135                 parent::__construct( $main, $action );
 136
 137                 $this->mModuleMgr = new ApiModuleManager( $this );
 138
 139                 // Allow custom modules to be added in LocalSettings.php
 140                 $config = $this->getConfig();
 141                 $this->mModuleMgr->addModules( self::$QueryPropModules, 'prop' );
 142                 $this->mModuleMgr->addModules( $config->get( 'APIPropModules' ), 'prop' );
 143                 $this->mModuleMgr->addModules( self::$QueryListModules, 'list' );
 144                 $this->mModuleMgr->addModules( $config->get( 'APIListModules' ), 'list' );
 145                 $this->mModuleMgr->addModules( self::$QueryMetaModules, 'meta' );
 146                 $this->mModuleMgr->addModules( $config->get( 'APIMetaModules' ), 'meta' );
 147
 148                 Hooks::run( 'ApiQuery::moduleManager', array( $this->mModuleMgr ) );
 149
 150                 // Create PageSet that will process titles/pageids/revids/generator
 151                 $this->mPageSet = new ApiPageSet( $this );
 152         }
 153
 154         /**
 155          * Overrides to return this instance's module manager.
 156          * @return ApiModuleManager
 157          */
 158         public function getModuleManager() {
 159                 return $this->mModuleMgr;
 160         }
 161
 162         /**
 163          * Get the query database connection with the given name.
 164          * If no such connection has been requested before, it will be created.
 165          * Subsequent calls with the same $name will return the same connection
 166          * as the first, regardless of the values of $db and $groups
 167          * @param string $name Name to assign to the database connection
 168          * @param int $db One of the DB_* constants
 169          * @param array $groups Query groups
 170          * @return DatabaseBase
 171          */
 172         public function getNamedDB( $name, $db, $groups ) {
 173                 if ( !array_key_exists( $name, $this->mNamedDB ) ) {
 174                         $this->mNamedDB[$name] = wfGetDB( $db, $groups );
 175                 }
 176
 177                 return $this->mNamedDB[$name];
 178         }
 179
 180         /**
 181          * Gets the set of pages the user has requested (or generated)
 182          * @return ApiPageSet
 183          */
 184         public function getPageSet() {
 185                 return $this->mPageSet;
 186         }
 187
 188         /**
 189          * Get the generators array mapping module names to class names
 190          * @deprecated since 1.21, list of generators is maintained by ApiPageSet
 191          * @return array Array(modulename => classname)
 192          */
 193         public function getGenerators() {
 194                 wfDeprecated( __METHOD__, '1.21' );
 195                 $gens = array();
 196                 foreach ( $this->mModuleMgr->getNamesWithClasses() as $name => $class ) {
 197                         if ( is_subclass_of( $class, 'ApiQueryGeneratorBase' ) ) {
 198                                 $gens[$name] = $class;
 199                         }
 200                 }
 201
 202                 return $gens;
 203         }
 204
 205         /**
 206          * Get whether the specified module is a prop, list or a meta query module
 207          * @deprecated since 1.21, use getModuleManager()->getModuleGroup()
 208          * @param string $moduleName Name of the module to find type for
 209          * @return string|null
 210          */
 211         function getModuleType( $moduleName ) {
 212                 return $this->getModuleManager()->getModuleGroup( $moduleName );
 213         }
 214
 215         /**
 216          * @return ApiFormatRaw|null
 217          */
 218         public function getCustomPrinter() {
 219                 // If &exportnowrap is set, use the raw formatter
 220                 if ( $this->getParameter( 'export' ) &&
 221                         $this->getParameter( 'exportnowrap' )
 222                 ) {
 223                         return new ApiFormatRaw( $this->getMain(),
 224                                 $this->getMain()->createPrinterByName( 'xml' ) );
 225                 } else {
 226                         return null;
 227                 }
 228         }
 229
 230         /**
 231          * Query execution happens in the following steps:
 232          * #1 Create a PageSet object with any pages requested by the user
 233          * #2 If using a generator, execute it to get a new ApiPageSet object
 234          * #3 Instantiate all requested modules.
 235          *    This way the PageSet object will know what shared data is required,
 236          *    and minimize DB calls.
 237          * #4 Output all normalization and redirect resolution information
 238          * #5 Execute all requested modules
 239          */
 240         public function execute() {
 241                 $this->mParams = $this->extractRequestParams();
 242
 243                 // Instantiate requested modules
 244                 $allModules = array();
 245                 $this->instantiateModules( $allModules, 'prop' );
 246                 $propModules = array_keys( $allModules );
 247                 $this->instantiateModules( $allModules, 'list' );
 248                 $this->instantiateModules( $allModules, 'meta' );
 249
 250                 // Filter modules based on continue parameter
 251                 $continuationManager = new ApiContinuationManager( $this, $allModules, $propModules );
 252                 $this->setContinuationManager( $continuationManager );
 253                 $modules = $continuationManager->getRunModules();
 254
 255                 if ( !$continuationManager->isGeneratorDone() ) {
 256                         // Query modules may optimize data requests through the $this->getPageSet()
 257                         // object by adding extra fields from the page table.
 258                         foreach ( $modules as $module ) {
 259                                 $module->requestExtraData( $this->mPageSet );
 260                         }
 261                         // Populate page/revision information
 262                         $this->mPageSet->execute();
 263                         // Record page information (title, namespace, if exists, etc)
 264                         $this->outputGeneralPageInfo();
 265                 } else {
 266                         $this->mPageSet->executeDryRun();
 267                 }
 268
 269                 $cacheMode = $this->mPageSet->getCacheMode();
 270
 271                 // Execute all unfinished modules
 272                 /** @var $module ApiQueryBase */
 273                 foreach ( $modules as $module ) {
 274                         $params = $module->extractRequestParams();
 275                         $cacheMode = $this->mergeCacheMode(
 276                                 $cacheMode, $module->getCacheMode( $params ) );
 277                         $module->execute();
 278                         Hooks::run( 'APIQueryAfterExecute', array( &$module ) );
 279                 }
 280
 281                 // Set the cache mode
 282                 $this->getMain()->setCacheMode( $cacheMode );
 283
 284                 // Write the continuation data into the result
 285                 $this->setContinuationManager( null );
 286                 if ( $this->mParams['rawcontinue'] ) {
 287                         $data = $continuationManager->getRawContinuation();
 288                         if ( $data ) {
 289                                 $this->getResult()->addValue( null, 'query-continue', $data,
 290                                         ApiResult::ADD_ON_TOP | ApiResult::NO_SIZE_CHECK );
 291                         }
 292                 } else {
 293                         $continuationManager->setContinuationIntoResult( $this->getResult() );
 294                 }
 295         }
 296
 297         /**
 298          * Update a cache mode string, applying the cache mode of a new module to it.
 299          * The cache mode may increase in the level of privacy, but public modules
 300          * added to private data do not decrease the level of privacy.
 301          *
 302          * @param string $cacheMode
 303          * @param string $modCacheMode
 304          * @return string
 305          */
 306         protected function mergeCacheMode( $cacheMode, $modCacheMode ) {
 307                 if ( $modCacheMode === 'anon-public-user-private' ) {
 308                         if ( $cacheMode !== 'private' ) {
 309                                 $cacheMode = 'anon-public-user-private';
 310                         }
 311                 } elseif ( $modCacheMode === 'public' ) {
 312                         // do nothing, if it's public already it will stay public
 313                 } else { // private
 314                         $cacheMode = 'private';
 315                 }
 316
 317                 return $cacheMode;
 318         }
 319
 320         /**
 321          * Create instances of all modules requested by the client
 322          * @param array $modules To append instantiated modules to
 323          * @param string $param Parameter name to read modules from
 324          */
 325         private function instantiateModules( &$modules, $param ) {
 326                 $wasPosted = $this->getRequest()->wasPosted();
 327                 if ( isset( $this->mParams[$param] ) ) {
 328                         foreach ( $this->mParams[$param] as $moduleName ) {
 329                                 $instance = $this->mModuleMgr->getModule( $moduleName, $param );
 330                                 if ( $instance === null ) {
 331                                         ApiBase::dieDebug( __METHOD__, 'Error instantiating module' );
 332                                 }
 333                                 if ( !$wasPosted && $instance->mustBePosted() ) {
 334                                         $this->dieUsageMsgOrDebug( array( 'mustbeposted', $moduleName ) );
 335                                 }
 336                                 // Ignore duplicates. TODO 2.0: die()?
 337                                 if ( !array_key_exists( $moduleName, $modules ) ) {
 338                                         $modules[$moduleName] = $instance;
 339                                 }
 340                         }
 341                 }
 342         }
 343
 344         /**
 345          * Appends an element for each page in the current pageSet with the
 346          * most general information (id, title), plus any title normalizations
 347          * and missing or invalid title/pageids/revids.
 348          */
 349         private function outputGeneralPageInfo() {
 350                 $pageSet = $this->getPageSet();
 351                 $result = $this->getResult();
 352
 353                 // We can't really handle max-result-size failure here, but we need to
 354                 // check anyway in case someone set the limit stupidly low.
 355                 $fit = true;
 356
 357                 $values = $pageSet->getNormalizedTitlesAsResult( $result );
 358                 if ( $values ) {
 359                         $fit = $fit && $result->addValue( 'query', 'normalized', $values );
 360                 }
 361                 $values = $pageSet->getConvertedTitlesAsResult( $result );
 362                 if ( $values ) {
 363                         $fit = $fit && $result->addValue( 'query', 'converted', $values );
 364                 }
 365                 $values = $pageSet->getInterwikiTitlesAsResult( $result, $this->mParams['iwurl'] );
 366                 if ( $values ) {
 367                         $fit = $fit && $result->addValue( 'query', 'interwiki', $values );
 368                 }
 369                 $values = $pageSet->getRedirectTitlesAsResult( $result );
 370                 if ( $values ) {
 371                         $fit = $fit && $result->addValue( 'query', 'redirects', $values );
 372                 }
 373                 $values = $pageSet->getMissingRevisionIDsAsResult( $result );
 374                 if ( $values ) {
 375                         $fit = $fit && $result->addValue( 'query', 'badrevids', $values );
 376                 }
 377
 378                 // Page elements
 379                 $pages = array();
 380
 381                 // Report any missing titles
 382                 foreach ( $pageSet->getMissingTitles() as $fakeId => $title ) {
 383                         $vals = array();
 384                         ApiQueryBase::addTitleInfo( $vals, $title );
 385                         $vals['missing'] = true;
 386                         $pages[$fakeId] = $vals;
 387                 }
 388                 // Report any invalid titles
 389                 foreach ( $pageSet->getInvalidTitlesAndReasons() as $fakeId => $data ) {
 390                         $pages[$fakeId] = $data + array( 'invalid' => true );
 391                 }
 392                 // Report any missing page ids
 393                 foreach ( $pageSet->getMissingPageIDs() as $pageid ) {
 394                         $pages[$pageid] = array(
 395                                 'pageid' => $pageid,
 396                                 'missing' => true
 397                         );
 398                 }
 399                 // Report special pages
 400                 /** @var $title Title */
 401                 foreach ( $pageSet->getSpecialTitles() as $fakeId => $title ) {
 402                         $vals = array();
 403                         ApiQueryBase::addTitleInfo( $vals, $title );
 404                         $vals['special'] = true;
 405                         if ( $title->isSpecialPage() &&
 406                                 !SpecialPageFactory::exists( $title->getDBkey() )
 407                         ) {
 408                                 $vals['missing'] = true;
 409                         } elseif ( $title->getNamespace() == NS_MEDIA &&
 410                                 !wfFindFile( $title )
 411                         ) {
 412                                 $vals['missing'] = true;
 413                         }
 414                         $pages[$fakeId] = $vals;
 415                 }
 416
 417                 // Output general page information for found titles
 418                 foreach ( $pageSet->getGoodTitles() as $pageid => $title ) {
 419                         $vals = array();
 420                         $vals['pageid'] = $pageid;
 421                         ApiQueryBase::addTitleInfo( $vals, $title );
 422                         $pages[$pageid] = $vals;
 423                 }
 424
 425                 if ( count( $pages ) ) {
 426                         $pageSet->populateGeneratorData( $pages );
 427                         ApiResult::setArrayType( $pages, 'BCarray' );
 428
 429                         if ( $this->mParams['indexpageids'] ) {
 430                                 $pageIDs = array_keys( ApiResult::stripMetadataNonRecursive( $pages ) );
 431                                 // json treats all map keys as strings - converting to match
 432                                 $pageIDs = array_map( 'strval', $pageIDs );
 433                                 ApiResult::setIndexedTagName( $pageIDs, 'id' );
 434                                 $fit = $fit && $result->addValue( 'query', 'pageids', $pageIDs );
 435                         }
 436
 437                         ApiResult::setIndexedTagName( $pages, 'page' );
 438                         $fit = $fit && $result->addValue( 'query', 'pages', $pages );
 439                 }
 440
 441                 if ( !$fit ) {
 442                         $this->dieUsage(
 443                                 'The value of $wgAPIMaxResultSize on this wiki is ' .
 444                                         'too small to hold basic result information',
 445                                 'badconfig'
 446                         );
 447                 }
 448
 449                 if ( $this->mParams['export'] ) {
 450                         $this->doExport( $pageSet, $result );
 451                 }
 452         }
 453
 454         /**
 455          * This method is called by the generator base when generator in the smart-continue
 456          * mode tries to set 'query-continue' value. ApiQuery stores those values separately
 457          * until the post-processing when it is known if the generation should continue or repeat.
 458          * @deprecated since 1.24
 459          * @param ApiQueryGeneratorBase $module Generator module
 460          * @param string $paramName
 461          * @param mixed $paramValue
 462          * @return bool True if processed, false if this is a legacy continue
 463          */
 464         public function setGeneratorContinue( $module, $paramName, $paramValue ) {
 465                 wfDeprecated( __METHOD__, '1.24' );
 466                 $this->getContinuationManager()->addGeneratorContinueParam( $module, $paramName, $paramValue );
 467                 return !$this->getParameter( 'rawcontinue' );
 468         }
 469
 470         /**
 471          * @param ApiPageSet $pageSet Pages to be exported
 472          * @param ApiResult $result Result to output to
 473          */
 474         private function doExport( $pageSet, $result ) {
 475                 $exportTitles = array();
 476                 $titles = $pageSet->getGoodTitles();
 477                 if ( count( $titles ) ) {
 478                         $user = $this->getUser();
 479                         /** @var $title Title */
 480                         foreach ( $titles as $title ) {
 481                                 if ( $title->userCan( 'read', $user ) ) {
 482                                         $exportTitles[] = $title;
 483                                 }
 484                         }
 485                 }
 486
 487                 $exporter = new WikiExporter( $this->getDB() );
 488                 // WikiExporter writes to stdout, so catch its
 489                 // output with an ob
 490                 ob_start();
 491                 $exporter->openStream();
 492                 foreach ( $exportTitles as $title ) {
 493                         $exporter->pageByTitle( $title );
 494                 }
 495                 $exporter->closeStream();
 496                 $exportxml = ob_get_contents();
 497                 ob_end_clean();
 498
 499                 // Don't check the size of exported stuff
 500                 // It's not continuable, so it would cause more
 501                 // problems than it'd solve
 502                 if ( $this->mParams['exportnowrap'] ) {
 503                         $result->reset();
 504                         // Raw formatter will handle this
 505                         $result->addValue( null, 'text', $exportxml, ApiResult::NO_SIZE_CHECK );
 506                         $result->addValue( null, 'mime', 'text/xml', ApiResult::NO_SIZE_CHECK );
 507                 } else {
 508                         $result->addValue( 'query', 'export', $exportxml, ApiResult::NO_SIZE_CHECK );
 509                         $result->addValue( 'query', ApiResult::META_BC_SUBELEMENTS, array( 'export' ) );
 510                 }
 511         }
 512
 513         public function getAllowedParams( $flags = 0 ) {
 514                 $result = array(
 515                         'prop' => array(
 516                                 ApiBase::PARAM_ISMULTI => true,
 517                                 ApiBase::PARAM_TYPE => 'submodule',
 518                         ),
 519                         'list' => array(
 520                                 ApiBase::PARAM_ISMULTI => true,
 521                                 ApiBase::PARAM_TYPE => 'submodule',
 522                         ),
 523                         'meta' => array(
 524                                 ApiBase::PARAM_ISMULTI => true,
 525                                 ApiBase::PARAM_TYPE => 'submodule',
 526                         ),
 527                         'indexpageids' => false,
 528                         'export' => false,
 529                         'exportnowrap' => false,
 530                         'iwurl' => false,
 531                         'continue' => array(
 532                                 ApiBase::PARAM_HELP_MSG => 'api-help-param-continue',
 533                         ),
 534                         'rawcontinue' => false,
 535                 );
 536                 if ( $flags ) {
 537                         $result += $this->getPageSet()->getFinalParams( $flags );
 538                 }
 539
 540                 return $result;
 541         }
 542
 543         /**
 544          * Override the parent to generate help messages for all available query modules.
 545          * @deprecated since 1.25
 546          * @return string
 547          */
 548         public function makeHelpMsg() {
 549                 wfDeprecated( __METHOD__, '1.25' );
 550
 551                 // Use parent to make default message for the query module
 552                 $msg = parent::makeHelpMsg();
 553
 554                 $querySeparator = str_repeat( '--- ', 12 );
 555                 $moduleSeparator = str_repeat( '*** ', 14 );
 556                 $msg .= "\n$querySeparator Query: Prop  $querySeparator\n\n";
 557                 $msg .= $this->makeHelpMsgHelper( 'prop' );
 558                 $msg .= "\n$querySeparator Query: List  $querySeparator\n\n";
 559                 $msg .= $this->makeHelpMsgHelper( 'list' );
 560                 $msg .= "\n$querySeparator Query: Meta  $querySeparator\n\n";
 561                 $msg .= $this->makeHelpMsgHelper( 'meta' );
 562                 $msg .= "\n\n$moduleSeparator Modules: continuation  $moduleSeparator\n\n";
 563
 564                 return $msg;
 565         }
 566
 567         /**
 568          * For all modules of a given group, generate help messages and join them together
 569          * @deprecated since 1.25
 570          * @param string $group Module group
 571          * @return string
 572          */
 573         private function makeHelpMsgHelper( $group ) {
 574                 $moduleDescriptions = array();
 575
 576                 $moduleNames = $this->mModuleMgr->getNames( $group );
 577                 sort( $moduleNames );
 578                 foreach ( $moduleNames as $name ) {
 579                         /**
 580                          * @var $module ApiQueryBase
 581                          */
 582                         $module = $this->mModuleMgr->getModule( $name );
 583
 584                         $msg = ApiMain::makeHelpMsgHeader( $module, $group );
 585                         $msg2 = $module->makeHelpMsg();
 586                         if ( $msg2 !== false ) {
 587                                 $msg .= $msg2;
 588                         }
 589                         if ( $module instanceof ApiQueryGeneratorBase ) {
 590                                 $msg .= "Generator:\n  This module may be used as a generator\n";
 591                         }
 592                         $moduleDescriptions[] = $msg;
 593                 }
 594
 595                 return implode( "\n", $moduleDescriptions );
 596         }
 597
 598         protected function getExamplesMessages() {
 599                 return array(
 600                         'action=query&prop=revisions&meta=siteinfo&' .
 601                                 'titles=Main%20Page&rvprop=user|comment&continue='
 602                                 => 'apihelp-query-example-revisions',
 603                         'action=query&generator=allpages&gapprefix=API/&prop=revisions&continue='
 604                                 => 'apihelp-query-example-allpages',
 605                 );
 606         }
 607
 608         public function getHelpUrls() {
 609                 return array(
 610                         'https://www.mediawiki.org/wiki/API:Query',
 611                         'https://www.mediawiki.org/wiki/API:Meta',
 612                         'https://www.mediawiki.org/wiki/API:Properties',
 613                         'https://www.mediawiki.org/wiki/API:Lists',
 614                 );
 615         }
 616 }