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                 'alltransclusions' => 'ApiQueryAllLinks',
  80                 'allusers' => 'ApiQueryAllUsers',
  81                 'backlinks' => 'ApiQueryBacklinks',
  82                 'blocks' => 'ApiQueryBlocks',
  83                 'categorymembers' => 'ApiQueryCategoryMembers',
  84                 'deletedrevs' => 'ApiQueryDeletedrevs',
  85                 'embeddedin' => 'ApiQueryBacklinks',
  86                 'exturlusage' => 'ApiQueryExtLinksUsage',
  87                 'filearchive' => 'ApiQueryFilearchive',
  88                 'imageusage' => 'ApiQueryBacklinks',
  89                 'iwbacklinks' => 'ApiQueryIWBacklinks',
  90                 'langbacklinks' => 'ApiQueryLangBacklinks',
  91                 'logevents' => 'ApiQueryLogEvents',
  92                 'pageswithprop' => 'ApiQueryPagesWithProp',
  93                 'pagepropnames' => 'ApiQueryPagePropNames',
  94                 'prefixsearch' => 'ApiQueryPrefixSearch',
  95                 'protectedtitles' => 'ApiQueryProtectedTitles',
  96                 'querypage' => 'ApiQueryQueryPage',
  97                 'random' => 'ApiQueryRandom',
  98                 'recentchanges' => 'ApiQueryRecentChanges',
  99                 'search' => 'ApiQuerySearch',
 100                 'tags' => 'ApiQueryTags',
 101                 'usercontribs' => 'ApiQueryContributions',
 102                 'users' => 'ApiQueryUsers',
 103                 'watchlist' => 'ApiQueryWatchlist',
 104                 'watchlistraw' => 'ApiQueryWatchlistRaw',
 105         );
 106
 107         /**
 108          * List of Api Query meta modules
 109          * @var array
 110          */
 111         private static $QueryMetaModules = array(
 112                 'allmessages' => 'ApiQueryAllMessages',
 113                 'siteinfo' => 'ApiQuerySiteinfo',
 114                 'userinfo' => 'ApiQueryUserInfo',
 115                 'filerepoinfo' => 'ApiQueryFileRepoInfo',
 116                 'tokens' => 'ApiQueryTokens',
 117         );
 118
 119         /**
 120          * @var ApiPageSet
 121          */
 122         private $mPageSet;
 123
 124         private $mParams;
 125         private $mNamedDB = array();
 126         private $mModuleMgr;
 127
 128         /**
 129          * @param ApiMain $main
 130          * @param string $action
 131          */
 132         public function __construct( ApiMain $main, $action ) {
 133                 parent::__construct( $main, $action );
 134
 135                 $this->mModuleMgr = new ApiModuleManager( $this );
 136
 137                 // Allow custom modules to be added in LocalSettings.php
 138                 $config = $this->getConfig();
 139                 $this->mModuleMgr->addModules( self::$QueryPropModules, 'prop' );
 140                 $this->mModuleMgr->addModules( $config->get( 'APIPropModules' ), 'prop' );
 141                 $this->mModuleMgr->addModules( self::$QueryListModules, 'list' );
 142                 $this->mModuleMgr->addModules( $config->get( 'APIListModules' ), 'list' );
 143                 $this->mModuleMgr->addModules( self::$QueryMetaModules, 'meta' );
 144                 $this->mModuleMgr->addModules( $config->get( 'APIMetaModules' ), 'meta' );
 145
 146                 // Create PageSet that will process titles/pageids/revids/generator
 147                 $this->mPageSet = new ApiPageSet( $this );
 148         }
 149
 150         /**
 151          * Overrides to return this instance's module manager.
 152          * @return ApiModuleManager
 153          */
 154         public function getModuleManager() {
 155                 return $this->mModuleMgr;
 156         }
 157
 158         /**
 159          * Get the query database connection with the given name.
 160          * If no such connection has been requested before, it will be created.
 161          * Subsequent calls with the same $name will return the same connection
 162          * as the first, regardless of the values of $db and $groups
 163          * @param string $name Name to assign to the database connection
 164          * @param int $db One of the DB_* constants
 165          * @param array $groups Query groups
 166          * @return DatabaseBase
 167          */
 168         public function getNamedDB( $name, $db, $groups ) {
 169                 if ( !array_key_exists( $name, $this->mNamedDB ) ) {
 170                         $this->profileDBIn();
 171                         $this->mNamedDB[$name] = wfGetDB( $db, $groups );
 172                         $this->profileDBOut();
 173                 }
 174
 175                 return $this->mNamedDB[$name];
 176         }
 177
 178         /**
 179          * Gets the set of pages the user has requested (or generated)
 180          * @return ApiPageSet
 181          */
 182         public function getPageSet() {
 183                 return $this->mPageSet;
 184         }
 185
 186         /**
 187          * Get the array mapping module names to class names
 188          * @deprecated since 1.21, use getModuleManager()'s methods instead
 189          * @return array Array(modulename => classname)
 190          */
 191         public function getModules() {
 192                 wfDeprecated( __METHOD__, '1.21' );
 193
 194                 return $this->getModuleManager()->getNamesWithClasses();
 195         }
 196
 197         /**
 198          * Get the generators array mapping module names to class names
 199          * @deprecated since 1.21, list of generators is maintained by ApiPageSet
 200          * @return array Array(modulename => classname)
 201          */
 202         public function getGenerators() {
 203                 wfDeprecated( __METHOD__, '1.21' );
 204                 $gens = array();
 205                 foreach ( $this->mModuleMgr->getNamesWithClasses() as $name => $class ) {
 206                         if ( is_subclass_of( $class, 'ApiQueryGeneratorBase' ) ) {
 207                                 $gens[$name] = $class;
 208                         }
 209                 }
 210
 211                 return $gens;
 212         }
 213
 214         /**
 215          * Get whether the specified module is a prop, list or a meta query module
 216          * @deprecated since 1.21, use getModuleManager()->getModuleGroup()
 217          * @param string $moduleName Name of the module to find type for
 218          * @return string|null
 219          */
 220         function getModuleType( $moduleName ) {
 221                 return $this->getModuleManager()->getModuleGroup( $moduleName );
 222         }
 223
 224         /**
 225          * @return ApiFormatRaw|null
 226          */
 227         public function getCustomPrinter() {
 228                 // If &exportnowrap is set, use the raw formatter
 229                 if ( $this->getParameter( 'export' ) &&
 230                         $this->getParameter( 'exportnowrap' )
 231                 ) {
 232                         return new ApiFormatRaw( $this->getMain(),
 233                                 $this->getMain()->createPrinterByName( 'xml' ) );
 234                 } else {
 235                         return null;
 236                 }
 237         }
 238
 239         /**
 240          * Query execution happens in the following steps:
 241          * #1 Create a PageSet object with any pages requested by the user
 242          * #2 If using a generator, execute it to get a new ApiPageSet object
 243          * #3 Instantiate all requested modules.
 244          *    This way the PageSet object will know what shared data is required,
 245          *    and minimize DB calls.
 246          * #4 Output all normalization and redirect resolution information
 247          * #5 Execute all requested modules
 248          */
 249         public function execute() {
 250                 $this->mParams = $this->extractRequestParams();
 251
 252                 if ( $this->mParams['continue'] === null && !$this->mParams['rawcontinue'] ) {
 253                         $this->logFeatureUsage( 'action=query&!rawcontinue&!continue' );
 254                         $this->setWarning(
 255                                 'Formatting of continuation data will be changing soon. ' .
 256                                 'To continue using the current formatting, use the \'rawcontinue\' parameter. ' .
 257                                 'To begin using the new format, pass an empty string for \'continue\' ' .
 258                                 'in the initial query.'
 259                         );
 260                 }
 261
 262                 // Instantiate requested modules
 263                 $allModules = array();
 264                 $this->instantiateModules( $allModules, 'prop' );
 265                 $propModules = array_keys( $allModules );
 266                 $this->instantiateModules( $allModules, 'list' );
 267                 $this->instantiateModules( $allModules, 'meta' );
 268
 269                 // Filter modules based on continue parameter
 270                 list( $generatorDone, $modules ) = $this->getResult()->beginContinuation(
 271                         $this->mParams['continue'], $allModules, $propModules
 272                 );
 273
 274                 if ( !$generatorDone ) {
 275                         // Query modules may optimize data requests through the $this->getPageSet()
 276                         // object by adding extra fields from the page table.
 277                         foreach ( $modules as $module ) {
 278                                 $module->requestExtraData( $this->mPageSet );
 279                         }
 280                         // Populate page/revision information
 281                         $this->mPageSet->execute();
 282                         // Record page information (title, namespace, if exists, etc)
 283                         $this->outputGeneralPageInfo();
 284                 } else {
 285                         $this->mPageSet->executeDryRun();
 286                 }
 287
 288                 $cacheMode = $this->mPageSet->getCacheMode();
 289
 290                 // Execute all unfinished modules
 291                 /** @var $module ApiQueryBase */
 292                 foreach ( $modules as $module ) {
 293                         $params = $module->extractRequestParams();
 294                         $cacheMode = $this->mergeCacheMode(
 295                                 $cacheMode, $module->getCacheMode( $params ) );
 296                         $module->profileIn();
 297                         $module->execute();
 298                         Hooks::run( 'APIQueryAfterExecute', array( &$module ) );
 299                         $module->profileOut();
 300                 }
 301
 302                 // Set the cache mode
 303                 $this->getMain()->setCacheMode( $cacheMode );
 304
 305                 // Write the continuation data into the result
 306                 $this->getResult()->endContinuation(
 307                         $this->mParams['continue'] === null ? 'raw' : 'standard'
 308                 );
 309         }
 310
 311         /**
 312          * Update a cache mode string, applying the cache mode of a new module to it.
 313          * The cache mode may increase in the level of privacy, but public modules
 314          * added to private data do not decrease the level of privacy.
 315          *
 316          * @param string $cacheMode
 317          * @param string $modCacheMode
 318          * @return string
 319          */
 320         protected function mergeCacheMode( $cacheMode, $modCacheMode ) {
 321                 if ( $modCacheMode === 'anon-public-user-private' ) {
 322                         if ( $cacheMode !== 'private' ) {
 323                                 $cacheMode = 'anon-public-user-private';
 324                         }
 325                 } elseif ( $modCacheMode === 'public' ) {
 326                         // do nothing, if it's public already it will stay public
 327                 } else { // private
 328                         $cacheMode = 'private';
 329                 }
 330
 331                 return $cacheMode;
 332         }
 333
 334         /**
 335          * Create instances of all modules requested by the client
 336          * @param array $modules To append instantiated modules to
 337          * @param string $param Parameter name to read modules from
 338          */
 339         private function instantiateModules( &$modules, $param ) {
 340                 $wasPosted = $this->getRequest()->wasPosted();
 341                 if ( isset( $this->mParams[$param] ) ) {
 342                         foreach ( $this->mParams[$param] as $moduleName ) {
 343                                 $instance = $this->mModuleMgr->getModule( $moduleName, $param );
 344                                 if ( $instance === null ) {
 345                                         ApiBase::dieDebug( __METHOD__, 'Error instantiating module' );
 346                                 }
 347                                 if ( !$wasPosted && $instance->mustBePosted() ) {
 348                                         $this->dieUsageMsgOrDebug( array( 'mustbeposted', $moduleName ) );
 349                                 }
 350                                 // Ignore duplicates. TODO 2.0: die()?
 351                                 if ( !array_key_exists( $moduleName, $modules ) ) {
 352                                         $modules[$moduleName] = $instance;
 353                                 }
 354                         }
 355                 }
 356         }
 357
 358         /**
 359          * Appends an element for each page in the current pageSet with the
 360          * most general information (id, title), plus any title normalizations
 361          * and missing or invalid title/pageids/revids.
 362          */
 363         private function outputGeneralPageInfo() {
 364                 $pageSet = $this->getPageSet();
 365                 $result = $this->getResult();
 366
 367                 // We can't really handle max-result-size failure here, but we need to
 368                 // check anyway in case someone set the limit stupidly low.
 369                 $fit = true;
 370
 371                 $values = $pageSet->getNormalizedTitlesAsResult( $result );
 372                 if ( $values ) {
 373                         $fit = $fit && $result->addValue( 'query', 'normalized', $values );
 374                 }
 375                 $values = $pageSet->getConvertedTitlesAsResult( $result );
 376                 if ( $values ) {
 377                         $fit = $fit && $result->addValue( 'query', 'converted', $values );
 378                 }
 379                 $values = $pageSet->getInterwikiTitlesAsResult( $result, $this->mParams['iwurl'] );
 380                 if ( $values ) {
 381                         $fit = $fit && $result->addValue( 'query', 'interwiki', $values );
 382                 }
 383                 $values = $pageSet->getRedirectTitlesAsResult( $result );
 384                 if ( $values ) {
 385                         $fit = $fit && $result->addValue( 'query', 'redirects', $values );
 386                 }
 387                 $values = $pageSet->getMissingRevisionIDsAsResult( $result );
 388                 if ( $values ) {
 389                         $fit = $fit && $result->addValue( 'query', 'badrevids', $values );
 390                 }
 391
 392                 // Page elements
 393                 $pages = array();
 394
 395                 // Report any missing titles
 396                 foreach ( $pageSet->getMissingTitles() as $fakeId => $title ) {
 397                         $vals = array();
 398                         ApiQueryBase::addTitleInfo( $vals, $title );
 399                         $vals['missing'] = '';
 400                         $pages[$fakeId] = $vals;
 401                 }
 402                 // Report any invalid titles
 403                 foreach ( $pageSet->getInvalidTitles() as $fakeId => $title ) {
 404                         $pages[$fakeId] = array( 'title' => $title, 'invalid' => '' );
 405                 }
 406                 // Report any missing page ids
 407                 foreach ( $pageSet->getMissingPageIDs() as $pageid ) {
 408                         $pages[$pageid] = array(
 409                                 'pageid' => $pageid,
 410                                 'missing' => ''
 411                         );
 412                 }
 413                 // Report special pages
 414                 /** @var $title Title */
 415                 foreach ( $pageSet->getSpecialTitles() as $fakeId => $title ) {
 416                         $vals = array();
 417                         ApiQueryBase::addTitleInfo( $vals, $title );
 418                         $vals['special'] = '';
 419                         if ( $title->isSpecialPage() &&
 420                                 !SpecialPageFactory::exists( $title->getDBkey() )
 421                         ) {
 422                                 $vals['missing'] = '';
 423                         } elseif ( $title->getNamespace() == NS_MEDIA &&
 424                                 !wfFindFile( $title )
 425                         ) {
 426                                 $vals['missing'] = '';
 427                         }
 428                         $pages[$fakeId] = $vals;
 429                 }
 430
 431                 // Output general page information for found titles
 432                 foreach ( $pageSet->getGoodTitles() as $pageid => $title ) {
 433                         $vals = array();
 434                         $vals['pageid'] = $pageid;
 435                         ApiQueryBase::addTitleInfo( $vals, $title );
 436                         $pages[$pageid] = $vals;
 437                 }
 438
 439                 if ( count( $pages ) ) {
 440                         $pageSet->populateGeneratorData( $pages );
 441
 442                         if ( $this->mParams['indexpageids'] ) {
 443                                 $pageIDs = array_keys( $pages );
 444                                 // json treats all map keys as strings - converting to match
 445                                 $pageIDs = array_map( 'strval', $pageIDs );
 446                                 $result->setIndexedTagName( $pageIDs, 'id' );
 447                                 $fit = $fit && $result->addValue( 'query', 'pageids', $pageIDs );
 448                         }
 449
 450                         $result->setIndexedTagName( $pages, 'page' );
 451                         $fit = $fit && $result->addValue( 'query', 'pages', $pages );
 452                 }
 453
 454                 if ( !$fit ) {
 455                         $this->dieUsage(
 456                                 'The value of $wgAPIMaxResultSize on this wiki is ' .
 457                                         'too small to hold basic result information',
 458                                 'badconfig'
 459                         );
 460                 }
 461
 462                 if ( $this->mParams['export'] ) {
 463                         $this->doExport( $pageSet, $result );
 464                 }
 465         }
 466
 467         /**
 468          * This method is called by the generator base when generator in the smart-continue
 469          * mode tries to set 'query-continue' value. ApiQuery stores those values separately
 470          * until the post-processing when it is known if the generation should continue or repeat.
 471          * @deprecated since 1.24
 472          * @param ApiQueryGeneratorBase $module Generator module
 473          * @param string $paramName
 474          * @param mixed $paramValue
 475          * @return bool True if processed, false if this is a legacy continue
 476          */
 477         public function setGeneratorContinue( $module, $paramName, $paramValue ) {
 478                 wfDeprecated( __METHOD__, '1.24' );
 479                 $this->getResult()->setGeneratorContinueParam( $module, $paramName, $paramValue );
 480                 return $this->getParameter( 'continue' ) !== null;
 481         }
 482
 483         /**
 484          * @param ApiPageSet $pageSet Pages to be exported
 485          * @param ApiResult $result Result to output to
 486          */
 487         private function doExport( $pageSet, $result ) {
 488                 $exportTitles = array();
 489                 $titles = $pageSet->getGoodTitles();
 490                 if ( count( $titles ) ) {
 491                         $user = $this->getUser();
 492                         /** @var $title Title */
 493                         foreach ( $titles as $title ) {
 494                                 if ( $title->userCan( 'read', $user ) ) {
 495                                         $exportTitles[] = $title;
 496                                 }
 497                         }
 498                 }
 499
 500                 $exporter = new WikiExporter( $this->getDB() );
 501                 // WikiExporter writes to stdout, so catch its
 502                 // output with an ob
 503                 ob_start();
 504                 $exporter->openStream();
 505                 foreach ( $exportTitles as $title ) {
 506                         $exporter->pageByTitle( $title );
 507                 }
 508                 $exporter->closeStream();
 509                 $exportxml = ob_get_contents();
 510                 ob_end_clean();
 511
 512                 // Don't check the size of exported stuff
 513                 // It's not continuable, so it would cause more
 514                 // problems than it'd solve
 515                 if ( $this->mParams['exportnowrap'] ) {
 516                         $result->reset();
 517                         // Raw formatter will handle this
 518                         $result->addValue( null, 'text', $exportxml, ApiResult::NO_SIZE_CHECK );
 519                         $result->addValue( null, 'mime', 'text/xml', ApiResult::NO_SIZE_CHECK );
 520                 } else {
 521                         $r = array();
 522                         ApiResult::setContent( $r, $exportxml );
 523                         $result->addValue( 'query', 'export', $r, ApiResult::NO_SIZE_CHECK );
 524                 }
 525         }
 526
 527         public function getAllowedParams( $flags = 0 ) {
 528                 $result = array(
 529                         'prop' => array(
 530                                 ApiBase::PARAM_ISMULTI => true,
 531                                 ApiBase::PARAM_TYPE => 'submodule',
 532                         ),
 533                         'list' => array(
 534                                 ApiBase::PARAM_ISMULTI => true,
 535                                 ApiBase::PARAM_TYPE => 'submodule',
 536                         ),
 537                         'meta' => array(
 538                                 ApiBase::PARAM_ISMULTI => true,
 539                                 ApiBase::PARAM_TYPE => 'submodule',
 540                         ),
 541                         'indexpageids' => false,
 542                         'export' => false,
 543                         'exportnowrap' => false,
 544                         'iwurl' => false,
 545                         'continue' => null,
 546                         'rawcontinue' => false,
 547                 );
 548                 if ( $flags ) {
 549                         $result += $this->getPageSet()->getFinalParams( $flags );
 550                 }
 551
 552                 return $result;
 553         }
 554
 555         /**
 556          * Override the parent to generate help messages for all available query modules.
 557          * @deprecated since 1.25
 558          * @return string
 559          */
 560         public function makeHelpMsg() {
 561                 wfDeprecated( __METHOD__, '1.25' );
 562
 563                 // Use parent to make default message for the query module
 564                 $msg = parent::makeHelpMsg();
 565
 566                 $querySeparator = str_repeat( '--- ', 12 );
 567                 $moduleSeparator = str_repeat( '*** ', 14 );
 568                 $msg .= "\n$querySeparator Query: Prop  $querySeparator\n\n";
 569                 $msg .= $this->makeHelpMsgHelper( 'prop' );
 570                 $msg .= "\n$querySeparator Query: List  $querySeparator\n\n";
 571                 $msg .= $this->makeHelpMsgHelper( 'list' );
 572                 $msg .= "\n$querySeparator Query: Meta  $querySeparator\n\n";
 573                 $msg .= $this->makeHelpMsgHelper( 'meta' );
 574                 $msg .= "\n\n$moduleSeparator Modules: continuation  $moduleSeparator\n\n";
 575
 576                 return $msg;
 577         }
 578
 579         /**
 580          * For all modules of a given group, generate help messages and join them together
 581          * @deprecated since 1.25
 582          * @param string $group Module group
 583          * @return string
 584          */
 585         private function makeHelpMsgHelper( $group ) {
 586                 $moduleDescriptions = array();
 587
 588                 $moduleNames = $this->mModuleMgr->getNames( $group );
 589                 sort( $moduleNames );
 590                 foreach ( $moduleNames as $name ) {
 591                         /**
 592                          * @var $module ApiQueryBase
 593                          */
 594                         $module = $this->mModuleMgr->getModule( $name );
 595
 596                         $msg = ApiMain::makeHelpMsgHeader( $module, $group );
 597                         $msg2 = $module->makeHelpMsg();
 598                         if ( $msg2 !== false ) {
 599                                 $msg .= $msg2;
 600                         }
 601                         if ( $module instanceof ApiQueryGeneratorBase ) {
 602                                 $msg .= "Generator:\n  This module may be used as a generator\n";
 603                         }
 604                         $moduleDescriptions[] = $msg;
 605                 }
 606
 607                 return implode( "\n", $moduleDescriptions );
 608         }
 609
 610         public function shouldCheckMaxlag() {
 611                 return true;
 612         }
 613
 614         protected function getExamplesMessages() {
 615                 return array(
 616                         'action=query&prop=revisions&meta=siteinfo&' .
 617                                 'titles=Main%20Page&rvprop=user|comment&continue='
 618                                 => 'apihelp-query-example-revisions',
 619                         'action=query&generator=allpages&gapprefix=API/&prop=revisions&continue='
 620                                 => 'apihelp-query-example-allpages',
 621                 );
 622         }
 623
 624         public function getHelpUrls() {
 625                 return array(
 626                         'https://www.mediawiki.org/wiki/API:Query',
 627                         'https://www.mediawiki.org/wiki/API:Meta',
 628                         'https://www.mediawiki.org/wiki/API:Properties',
 629                         'https://www.mediawiki.org/wiki/API:Lists',
 630                 );
 631         }
 632 }