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         private $mPropModuleNames, $mListModuleNames, $mMetaModuleNames;
  41
  42         /**
  43          * @var ApiPageSet
  44          */
  45         private $mPageSet;
  46
  47         private $params, $redirects, $convertTitles, $iwUrl;
  48
  49         private $mQueryPropModules = array(
  50                 'info' => 'ApiQueryInfo',
  51                 'revisions' => 'ApiQueryRevisions',
  52                 'links' => 'ApiQueryLinks',
  53                 'iwlinks' => 'ApiQueryIWLinks',
  54                 'langlinks' => 'ApiQueryLangLinks',
  55                 'images' => 'ApiQueryImages',
  56                 'imageinfo' => 'ApiQueryImageInfo',
  57                 'stashimageinfo' => 'ApiQueryStashImageInfo',
  58                 'templates' => 'ApiQueryLinks',
  59                 'categories' => 'ApiQueryCategories',
  60                 'extlinks' => 'ApiQueryExternalLinks',
  61                 'categoryinfo' => 'ApiQueryCategoryInfo',
  62                 'duplicatefiles' => 'ApiQueryDuplicateFiles',
  63                 'pageprops' => 'ApiQueryPageProps',
  64         );
  65
  66         private $mQueryListModules = array(
  67                 'allimages' => 'ApiQueryAllImages',
  68                 'allpages' => 'ApiQueryAllPages',
  69                 'alllinks' => 'ApiQueryAllLinks',
  70                 'allcategories' => 'ApiQueryAllCategories',
  71                 'allusers' => 'ApiQueryAllUsers',
  72                 'backlinks' => 'ApiQueryBacklinks',
  73                 'blocks' => 'ApiQueryBlocks',
  74                 'categorymembers' => 'ApiQueryCategoryMembers',
  75                 'deletedrevs' => 'ApiQueryDeletedrevs',
  76                 'embeddedin' => 'ApiQueryBacklinks',
  77                 'filearchive' => 'ApiQueryFilearchive',
  78                 'imageusage' => 'ApiQueryBacklinks',
  79                 'iwbacklinks' => 'ApiQueryIWBacklinks',
  80                 'langbacklinks' => 'ApiQueryLangBacklinks',
  81                 'logevents' => 'ApiQueryLogEvents',
  82                 'recentchanges' => 'ApiQueryRecentChanges',
  83                 'search' => 'ApiQuerySearch',
  84                 'tags' => 'ApiQueryTags',
  85                 'usercontribs' => 'ApiQueryContributions',
  86                 'watchlist' => 'ApiQueryWatchlist',
  87                 'watchlistraw' => 'ApiQueryWatchlistRaw',
  88                 'exturlusage' => 'ApiQueryExtLinksUsage',
  89                 'users' => 'ApiQueryUsers',
  90                 'random' => 'ApiQueryRandom',
  91                 'protectedtitles' => 'ApiQueryProtectedTitles',
  92                 'querypage' => 'ApiQueryQueryPage',
  93         );
  94
  95         private $mQueryMetaModules = array(
  96                 'siteinfo' => 'ApiQuerySiteinfo',
  97                 'userinfo' => 'ApiQueryUserInfo',
  98                 'allmessages' => 'ApiQueryAllMessages',
  99         );
 100
 101         private $mSlaveDB = null;
 102         private $mNamedDB = array();
 103
 104         protected $mAllowedGenerators = array();
 105
 106         /**
 107          * @param $main ApiMain
 108          * @param $action string
 109          */
 110         public function __construct( $main, $action ) {
 111                 parent::__construct( $main, $action );
 112
 113                 // Allow custom modules to be added in LocalSettings.php
 114                 global $wgAPIPropModules, $wgAPIListModules, $wgAPIMetaModules;
 115                 self::appendUserModules( $this->mQueryPropModules, $wgAPIPropModules );
 116                 self::appendUserModules( $this->mQueryListModules, $wgAPIListModules );
 117                 self::appendUserModules( $this->mQueryMetaModules, $wgAPIMetaModules );
 118
 119                 $this->mPropModuleNames = array_keys( $this->mQueryPropModules );
 120                 $this->mListModuleNames = array_keys( $this->mQueryListModules );
 121                 $this->mMetaModuleNames = array_keys( $this->mQueryMetaModules );
 122         }
 123
 124         /**
 125          * Helper function to append any add-in modules to the list
 126          * @param $modules array Module array
 127          * @param $newModules array Module array to add to $modules
 128          */
 129         private static function appendUserModules( &$modules, $newModules ) {
 130                 if ( is_array( $newModules ) ) {
 131                         foreach ( $newModules as $moduleName => $moduleClass ) {
 132                                 $modules[$moduleName] = $moduleClass;
 133                         }
 134                 }
 135         }
 136
 137         /**
 138          * Gets a default slave database connection object
 139          * @return DatabaseBase
 140          */
 141         public function getDB() {
 142                 if ( !isset( $this->mSlaveDB ) ) {
 143                         $this->profileDBIn();
 144                         $this->mSlaveDB = wfGetDB( DB_SLAVE, 'api' );
 145                         $this->profileDBOut();
 146                 }
 147                 return $this->mSlaveDB;
 148         }
 149
 150         /**
 151          * Get the query database connection with the given name.
 152          * If no such connection has been requested before, it will be created.
 153          * Subsequent calls with the same $name will return the same connection
 154          * as the first, regardless of the values of $db and $groups
 155          * @param $name string Name to assign to the database connection
 156          * @param $db int One of the DB_* constants
 157          * @param $groups array Query groups
 158          * @return DatabaseBase
 159          */
 160         public function getNamedDB( $name, $db, $groups ) {
 161                 if ( !array_key_exists( $name, $this->mNamedDB ) ) {
 162                         $this->profileDBIn();
 163                         $this->mNamedDB[$name] = wfGetDB( $db, $groups );
 164                         $this->profileDBOut();
 165                 }
 166                 return $this->mNamedDB[$name];
 167         }
 168
 169         /**
 170          * Gets the set of pages the user has requested (or generated)
 171          * @return ApiPageSet
 172          */
 173         public function getPageSet() {
 174                 return $this->mPageSet;
 175         }
 176
 177         /**
 178          * Get the array mapping module names to class names
 179          * @return array array(modulename => classname)
 180          */
 181         function getModules() {
 182                 return array_merge( $this->mQueryPropModules, $this->mQueryListModules, $this->mQueryMetaModules );
 183         }
 184
 185         /**
 186          * Get whether the specified module is a prop, list or a meta query module
 187          * @param $moduleName string Name of the module to find type for
 188          * @return mixed string or null
 189          */
 190         function getModuleType( $moduleName ) {
 191                 if ( isset( $this->mQueryPropModules[$moduleName] ) ) {
 192                         return 'prop';
 193                 }
 194
 195                 if ( isset( $this->mQueryListModules[$moduleName] ) ) {
 196                         return 'list';
 197                 }
 198
 199                 if ( isset( $this->mQueryMetaModules[$moduleName] ) ) {
 200                         return 'meta';
 201                 }
 202
 203                 return null;
 204         }
 205
 206         /**
 207          * @return ApiFormatRaw|null
 208          */
 209         public function getCustomPrinter() {
 210                 // If &exportnowrap is set, use the raw formatter
 211                 if ( $this->getParameter( 'export' ) &&
 212                                 $this->getParameter( 'exportnowrap' ) )
 213                 {
 214                         return new ApiFormatRaw( $this->getMain(),
 215                                 $this->getMain()->createPrinterByName( 'xml' ) );
 216                 } else {
 217                         return null;
 218                 }
 219         }
 220
 221         /**
 222          * Query execution happens in the following steps:
 223          * #1 Create a PageSet object with any pages requested by the user
 224          * #2 If using a generator, execute it to get a new ApiPageSet object
 225          * #3 Instantiate all requested modules.
 226          *    This way the PageSet object will know what shared data is required,
 227          *    and minimize DB calls.
 228          * #4 Output all normalization and redirect resolution information
 229          * #5 Execute all requested modules
 230          */
 231         public function execute() {
 232                 $this->params = $this->extractRequestParams();
 233                 $this->redirects = $this->params['redirects'];
 234                 $this->convertTitles = $this->params['converttitles'];
 235                 $this->iwUrl = $this->params['iwurl'];
 236
 237                 // Create PageSet
 238                 $this->mPageSet = new ApiPageSet( $this, $this->redirects, $this->convertTitles );
 239
 240                 // Instantiate requested modules
 241                 $modules = array();
 242                 $this->instantiateModules( $modules, 'prop', $this->mQueryPropModules );
 243                 $this->instantiateModules( $modules, 'list', $this->mQueryListModules );
 244                 $this->instantiateModules( $modules, 'meta', $this->mQueryMetaModules );
 245
 246                 $cacheMode = 'public';
 247
 248                 // If given, execute generator to substitute user supplied data with generated data.
 249                 if ( isset( $this->params['generator'] ) ) {
 250                         $generator = $this->newGenerator( $this->params['generator'] );
 251                         $params = $generator->extractRequestParams();
 252                         $cacheMode = $this->mergeCacheMode( $cacheMode,
 253                                 $generator->getCacheMode( $params ) );
 254                         $this->executeGeneratorModule( $generator, $modules );
 255                 } else {
 256                         // Append custom fields and populate page/revision information
 257                         $this->addCustomFldsToPageSet( $modules, $this->mPageSet );
 258                         $this->mPageSet->execute();
 259                 }
 260
 261                 // Record page information (title, namespace, if exists, etc)
 262                 $this->outputGeneralPageInfo();
 263
 264                 // Execute all requested modules.
 265                 /**
 266                  * @var $module ApiQueryBase
 267                  */
 268                 foreach ( $modules as $module ) {
 269                         $params = $module->extractRequestParams();
 270                         $cacheMode = $this->mergeCacheMode(
 271                                 $cacheMode, $module->getCacheMode( $params ) );
 272                         $module->profileIn();
 273                         $module->execute();
 274                         wfRunHooks( 'APIQueryAfterExecute', array( &$module ) );
 275                         $module->profileOut();
 276                 }
 277
 278                 // Set the cache mode
 279                 $this->getMain()->setCacheMode( $cacheMode );
 280         }
 281
 282         /**
 283          * Update a cache mode string, applying the cache mode of a new module to it.
 284          * The cache mode may increase in the level of privacy, but public modules
 285          * added to private data do not decrease the level of privacy.
 286          *
 287          * @param $cacheMode string
 288          * @param $modCacheMode string
 289          * @return string
 290          */
 291         protected function mergeCacheMode( $cacheMode, $modCacheMode ) {
 292                 if ( $modCacheMode === 'anon-public-user-private' ) {
 293                         if ( $cacheMode !== 'private' ) {
 294                                 $cacheMode = 'anon-public-user-private';
 295                         }
 296                 } elseif ( $modCacheMode === 'public' ) {
 297                         // do nothing, if it's public already it will stay public
 298                 } else { // private
 299                         $cacheMode = 'private';
 300                 }
 301                 return $cacheMode;
 302         }
 303
 304         /**
 305          * Query modules may optimize data requests through the $this->getPageSet() object
 306          * by adding extra fields from the page table.
 307          * This function will gather all the extra request fields from the modules.
 308          * @param $modules array of module objects
 309          * @param $pageSet ApiPageSet
 310          */
 311         private function addCustomFldsToPageSet( $modules, $pageSet ) {
 312                 // Query all requested modules.
 313                 /**
 314                  * @var $module ApiQueryBase
 315                  */
 316                 foreach ( $modules as $module ) {
 317                         $module->requestExtraData( $pageSet );
 318                 }
 319         }
 320
 321         /**
 322          * Create instances of all modules requested by the client
 323          * @param $modules Array to append instantiated modules to
 324          * @param $param string Parameter name to read modules from
 325          * @param $moduleList Array array(modulename => classname)
 326          */
 327         private function instantiateModules( &$modules, $param, $moduleList ) {
 328                 if ( isset( $this->params[$param] ) ) {
 329                         foreach ( $this->params[$param] as $moduleName ) {
 330                                 $modules[] = new $moduleList[$moduleName] ( $this, $moduleName );
 331                         }
 332                 }
 333         }
 334
 335         /**
 336          * Appends an element for each page in the current pageSet with the
 337          * most general information (id, title), plus any title normalizations
 338          * and missing or invalid title/pageids/revids.
 339          */
 340         private function outputGeneralPageInfo() {
 341                 $pageSet = $this->getPageSet();
 342                 $result = $this->getResult();
 343
 344                 // We don't check for a full result set here because we can't be adding
 345                 // more than 380K. The maximum revision size is in the megabyte range,
 346                 // and the maximum result size must be even higher than that.
 347
 348                 // Title normalizations
 349                 $normValues = array();
 350                 foreach ( $pageSet->getNormalizedTitles() as $rawTitleStr => $titleStr ) {
 351                         $normValues[] = array(
 352                                 'from' => $rawTitleStr,
 353                                 'to' => $titleStr
 354                         );
 355                 }
 356
 357                 if ( count( $normValues ) ) {
 358                         $result->setIndexedTagName( $normValues, 'n' );
 359                         $result->addValue( 'query', 'normalized', $normValues );
 360                 }
 361
 362                 // Title conversions
 363                 $convValues = array();
 364                 foreach ( $pageSet->getConvertedTitles() as $rawTitleStr => $titleStr ) {
 365                         $convValues[] = array(
 366                                 'from' => $rawTitleStr,
 367                                 'to' => $titleStr
 368                         );
 369                 }
 370
 371                 if ( count( $convValues ) ) {
 372                         $result->setIndexedTagName( $convValues, 'c' );
 373                         $result->addValue( 'query', 'converted', $convValues );
 374                 }
 375
 376                 // Interwiki titles
 377                 $intrwValues = array();
 378                 foreach ( $pageSet->getInterwikiTitles() as $rawTitleStr => $interwikiStr ) {
 379                         $item = array(
 380                                 'title' => $rawTitleStr,
 381                                 'iw' => $interwikiStr,
 382                         );
 383                         if ( $this->iwUrl ) {
 384                                 $title = Title::newFromText( $rawTitleStr );
 385                                 $item['url'] = wfExpandUrl( $title->getFullURL(), PROTO_CURRENT );
 386                         }
 387                         $intrwValues[] = $item;
 388                 }
 389
 390                 if ( count( $intrwValues ) ) {
 391                         $result->setIndexedTagName( $intrwValues, 'i' );
 392                         $result->addValue( 'query', 'interwiki', $intrwValues );
 393                 }
 394
 395                 // Show redirect information
 396                 $redirValues = array();
 397                 /**
 398                  * @var $titleTo Title
 399                  */
 400                 foreach ( $pageSet->getRedirectTitles() as $titleStrFrom => $titleTo ) {
 401                         $r = array(
 402                                 'from' => strval( $titleStrFrom ),
 403                                 'to' => $titleTo->getPrefixedText(),
 404                         );
 405                         if ( $titleTo->getFragment() !== '' ) {
 406                                 $r['tofragment'] = $titleTo->getFragment();
 407                         }
 408                         $redirValues[] = $r;
 409                 }
 410
 411                 if ( count( $redirValues ) ) {
 412                         $result->setIndexedTagName( $redirValues, 'r' );
 413                         $result->addValue( 'query', 'redirects', $redirValues );
 414                 }
 415
 416                 // Missing revision elements
 417                 $missingRevIDs = $pageSet->getMissingRevisionIDs();
 418                 if ( count( $missingRevIDs ) ) {
 419                         $revids = array();
 420                         foreach ( $missingRevIDs as $revid ) {
 421                                 $revids[$revid] = array(
 422                                         'revid' => $revid
 423                                 );
 424                         }
 425                         $result->setIndexedTagName( $revids, 'rev' );
 426                         $result->addValue( 'query', 'badrevids', $revids );
 427                 }
 428
 429                 // Page elements
 430                 $pages = array();
 431
 432                 // Report any missing titles
 433                 foreach ( $pageSet->getMissingTitles() as $fakeId => $title ) {
 434                         $vals = array();
 435                         ApiQueryBase::addTitleInfo( $vals, $title );
 436                         $vals['missing'] = '';
 437                         $pages[$fakeId] = $vals;
 438                 }
 439                 // Report any invalid titles
 440                 foreach ( $pageSet->getInvalidTitles() as $fakeId => $title ) {
 441                         $pages[$fakeId] = array( 'title' => $title, 'invalid' => '' );
 442                 }
 443                 // Report any missing page ids
 444                 foreach ( $pageSet->getMissingPageIDs() as $pageid ) {
 445                         $pages[$pageid] = array(
 446                                 'pageid' => $pageid,
 447                                 'missing' => ''
 448                         );
 449                 }
 450                 // Report special pages
 451                 foreach ( $pageSet->getSpecialTitles() as $fakeId => $title ) {
 452                         $vals = array();
 453                         ApiQueryBase::addTitleInfo( $vals, $title );
 454                         $vals['special'] = '';
 455                         if ( $title->isSpecialPage() &&
 456                                         !SpecialPageFactory::exists( $title->getDbKey() ) ) {
 457                                 $vals['missing'] = '';
 458                         } elseif ( $title->getNamespace() == NS_MEDIA &&
 459                                         !wfFindFile( $title ) ) {
 460                                 $vals['missing'] = '';
 461                         }
 462                         $pages[$fakeId] = $vals;
 463                 }
 464
 465                 // Output general page information for found titles
 466                 foreach ( $pageSet->getGoodTitles() as $pageid => $title ) {
 467                         $vals = array();
 468                         $vals['pageid'] = $pageid;
 469                         ApiQueryBase::addTitleInfo( $vals, $title );
 470                         $pages[$pageid] = $vals;
 471                 }
 472
 473                 if ( count( $pages ) ) {
 474                         if ( $this->params['indexpageids'] ) {
 475                                 $pageIDs = array_keys( $pages );
 476                                 // json treats all map keys as strings - converting to match
 477                                 $pageIDs = array_map( 'strval', $pageIDs );
 478                                 $result->setIndexedTagName( $pageIDs, 'id' );
 479                                 $result->addValue( 'query', 'pageids', $pageIDs );
 480                         }
 481
 482                         $result->setIndexedTagName( $pages, 'page' );
 483                         $result->addValue( 'query', 'pages', $pages );
 484                 }
 485                 if ( $this->params['export'] ) {
 486                         $this->doExport( $pageSet, $result );
 487                 }
 488         }
 489
 490         /**
 491          * @param  $pageSet ApiPageSet Pages to be exported
 492          * @param  $result ApiResult Result to output to
 493          */
 494         private function doExport( $pageSet, $result )  {
 495                 $exportTitles = array();
 496                 $titles = $pageSet->getGoodTitles();
 497                 if ( count( $titles ) ) {
 498                         foreach ( $titles as $title ) {
 499                                 if ( $title->userCan( 'read' ) ) {
 500                                         $exportTitles[] = $title;
 501                                 }
 502                         }
 503                 }
 504
 505                 $exporter = new WikiExporter( $this->getDB() );
 506                 // WikiExporter writes to stdout, so catch its
 507                 // output with an ob
 508                 ob_start();
 509                 $exporter->openStream();
 510                 foreach ( $exportTitles as $title ) {
 511                         $exporter->pageByTitle( $title );
 512                 }
 513                 $exporter->closeStream();
 514                 $exportxml = ob_get_contents();
 515                 ob_end_clean();
 516
 517                 // Don't check the size of exported stuff
 518                 // It's not continuable, so it would cause more
 519                 // problems than it'd solve
 520                 $result->disableSizeCheck();
 521                 if ( $this->params['exportnowrap'] ) {
 522                         $result->reset();
 523                         // Raw formatter will handle this
 524                         $result->addValue( null, 'text', $exportxml );
 525                         $result->addValue( null, 'mime', 'text/xml' );
 526                 } else {
 527                         $r = array();
 528                         ApiResult::setContent( $r, $exportxml );
 529                         $result->addValue( 'query', 'export', $r );
 530                 }
 531                 $result->enableSizeCheck();
 532         }
 533
 534         /**
 535          * Create a generator object of the given type and return it
 536          * @param $generatorName string Module name
 537          * @return ApiQueryGeneratorBase
 538          */
 539         public function newGenerator( $generatorName ) {
 540                 // Find class that implements requested generator
 541                 if ( isset( $this->mQueryListModules[$generatorName] ) ) {
 542                         $className = $this->mQueryListModules[$generatorName];
 543                 } elseif ( isset( $this->mQueryPropModules[$generatorName] ) ) {
 544                         $className = $this->mQueryPropModules[$generatorName];
 545                 } else {
 546                         ApiBase::dieDebug( __METHOD__, "Unknown generator=$generatorName" );
 547                 }
 548                 $generator = new $className ( $this, $generatorName );
 549                 if ( !$generator instanceof ApiQueryGeneratorBase ) {
 550                         $this->dieUsage( "Module $generatorName cannot be used as a generator", 'badgenerator' );
 551                 }
 552                 $generator->setGeneratorMode();
 553                 return $generator;
 554         }
 555
 556         /**
 557          * For generator mode, execute generator, and use its output as new
 558          * ApiPageSet
 559          * @param $generator ApiQueryGeneratorBase Generator Module
 560          * @param $modules array of module objects
 561          */
 562         protected function executeGeneratorModule( $generator, $modules ) {
 563                 // Generator results
 564                 $resultPageSet = new ApiPageSet( $this, $this->redirects, $this->convertTitles );
 565
 566                 // Add any additional fields modules may need
 567                 $generator->requestExtraData( $this->mPageSet );
 568                 $this->addCustomFldsToPageSet( $modules, $resultPageSet );
 569
 570                 // Populate page information with the original user input
 571                 $this->mPageSet->execute();
 572
 573                 // populate resultPageSet with the generator output
 574                 $generator->profileIn();
 575                 $generator->executeGenerator( $resultPageSet );
 576                 wfRunHooks( 'APIQueryGeneratorAfterExecute', array( &$generator, &$resultPageSet ) );
 577                 $resultPageSet->finishPageSetGeneration();
 578                 $generator->profileOut();
 579
 580                 // Swap the resulting pageset back in
 581                 $this->mPageSet = $resultPageSet;
 582         }
 583
 584         public function getAllowedParams() {
 585                 return array(
 586                         'prop' => array(
 587                                 ApiBase::PARAM_ISMULTI => true,
 588                                 ApiBase::PARAM_TYPE => $this->mPropModuleNames
 589                         ),
 590                         'list' => array(
 591                                 ApiBase::PARAM_ISMULTI => true,
 592                                 ApiBase::PARAM_TYPE => $this->mListModuleNames
 593                         ),
 594                         'meta' => array(
 595                                 ApiBase::PARAM_ISMULTI => true,
 596                                 ApiBase::PARAM_TYPE => $this->mMetaModuleNames
 597                         ),
 598                         'generator' => array(
 599                                 ApiBase::PARAM_TYPE => $this->mAllowedGenerators
 600                         ),
 601                         'redirects' => false,
 602                         'converttitles' => false,
 603                         'indexpageids' => false,
 604                         'export' => false,
 605                         'exportnowrap' => false,
 606                         'iwurl' => false,
 607                 );
 608         }
 609
 610         /**
 611          * Override the parent to generate help messages for all available query modules.
 612          * @return string
 613          */
 614         public function makeHelpMsg() {
 615                 // Make sure the internal object is empty
 616                 // (just in case a sub-module decides to optimize during instantiation)
 617                 $this->mPageSet = null;
 618                 $this->mAllowedGenerators = array(); // Will be repopulated
 619
 620                 $querySeparator = str_repeat( '--- ', 12 );
 621                 $moduleSeparator = str_repeat( '*** ', 14 );
 622                 $msg = "\n$querySeparator Query: Prop  $querySeparator\n\n";
 623                 $msg .= $this->makeHelpMsgHelper( $this->mQueryPropModules, 'prop' );
 624                 $msg .= "\n$querySeparator Query: List  $querySeparator\n\n";
 625                 $msg .= $this->makeHelpMsgHelper( $this->mQueryListModules, 'list' );
 626                 $msg .= "\n$querySeparator Query: Meta  $querySeparator\n\n";
 627                 $msg .= $this->makeHelpMsgHelper( $this->mQueryMetaModules, 'meta' );
 628                 $msg .= "\n\n$moduleSeparator Modules: continuation  $moduleSeparator\n\n";
 629
 630                 // Perform the base call last because the $this->mAllowedGenerators
 631                 // will be updated inside makeHelpMsgHelper()
 632                 // Use parent to make default message for the query module
 633                 $msg = parent::makeHelpMsg() . $msg;
 634
 635                 return $msg;
 636         }
 637
 638         /**
 639          * For all modules in $moduleList, generate help messages and join them together
 640          * @param $moduleList Array array(modulename => classname)
 641          * @param $paramName string Parameter name
 642          * @return string
 643          */
 644         private function makeHelpMsgHelper( $moduleList, $paramName ) {
 645                 $moduleDescriptions = array();
 646
 647                 foreach ( $moduleList as $moduleName => $moduleClass ) {
 648                         /**
 649                          * @var $module ApiQueryBase
 650                          */
 651                         $module = new $moduleClass( $this, $moduleName, null );
 652
 653                         $msg = ApiMain::makeHelpMsgHeader( $module, $paramName );
 654                         $msg2 = $module->makeHelpMsg();
 655                         if ( $msg2 !== false ) {
 656                                 $msg .= $msg2;
 657                         }
 658                         if ( $module instanceof ApiQueryGeneratorBase ) {
 659                                 $this->mAllowedGenerators[] = $moduleName;
 660                                 $msg .= "Generator:\n  This module may be used as a generator\n";
 661                         }
 662                         $moduleDescriptions[] = $msg;
 663                 }
 664
 665                 return implode( "\n", $moduleDescriptions );
 666         }
 667
 668         /**
 669          * Override to add extra parameters from PageSet
 670          * @return string
 671          */
 672         public function makeHelpMsgParameters() {
 673                 $psModule = new ApiPageSet( $this );
 674                 return $psModule->makeHelpMsgParameters() . parent::makeHelpMsgParameters();
 675         }
 676
 677         public function shouldCheckMaxlag() {
 678                 return true;
 679         }
 680
 681         public function getParamDescription() {
 682                 return array(
 683                         'prop' => 'Which properties to get for the titles/revisions/pageids. Module help is available below',
 684                         'list' => 'Which lists to get. Module help is available below',
 685                         'meta' => 'Which metadata to get about the site. Module help is available below',
 686                         'generator' => array( 'Use the output of a list as the input for other prop/list/meta items',
 687                                         'NOTE: generator parameter names must be prefixed with a \'g\', see examples' ),
 688                         'redirects' => 'Automatically resolve redirects',
 689                         'converttitles' => array( "Convert titles to other variants if necessary. Only works if the wiki's content language supports variant conversion.",
 690                                         'Languages that support variant conversion include ' . implode( ', ', LanguageConverter::$languagesWithVariants ) ),
 691                         'indexpageids' => 'Include an additional pageids section listing all returned page IDs',
 692                         'export' => 'Export the current revisions of all given or generated pages',
 693                         'exportnowrap' => 'Return the export XML without wrapping it in an XML result (same format as Special:Export). Can only be used with export',
 694                         'iwurl' => 'Whether to get the full URL if the title is an interwiki link',
 695                 );
 696         }
 697
 698         public function getDescription() {
 699                 return array(
 700                         'Query API module allows applications to get needed pieces of data from the MediaWiki databases,',
 701                         'and is loosely based on the old query.php interface.',
 702                         'All data modifications will first have to use query to acquire a token to prevent abuse from malicious sites'
 703                 );
 704         }
 705
 706         public function getPossibleErrors() {
 707                 return array_merge( parent::getPossibleErrors(), array(
 708                         array( 'code' => 'badgenerator', 'info' => 'Module $generatorName cannot be used as a generator' ),
 709                 ) );
 710         }
 711
 712         public function getExamples() {
 713                 return array(
 714                         'api.php?action=query&prop=revisions&meta=siteinfo&titles=Main%20Page&rvprop=user|comment',
 715                         'api.php?action=query&generator=allpages&gapprefix=API/&prop=revisions',
 716                 );
 717         }
 718
 719         public function getHelpUrls() {
 720                 return array(
 721                         'https://www.mediawiki.org/wiki/API:Meta',
 722                         'https://www.mediawiki.org/wiki/API:Properties',
 723                         'https://www.mediawiki.org/wiki/API:Lists',
 724                 );
 725         }
 726
 727         public function getVersion() {
 728                 $psModule = new ApiPageSet( $this );
 729                 $vers = array();
 730                 $vers[] = __CLASS__ . ': $Id$';
 731                 $vers[] = $psModule->getVersion();
 732                 return $vers;
 733         }
 734 }