includes/Category.php

   1 <?php
   2 /**
   3  * Representation for a category.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @author Simetrical
  22  */
  23
  24 /**
  25  * Category objects are immutable, strictly speaking. If you call methods that change the database,
  26  * like to refresh link counts, the objects will be appropriately reinitialized.
  27  * Member variables are lazy-initialized.
  28  *
  29  * @todo Move some stuff from CategoryPage.php to here, and use that.
  30  */
  31 class Category {
  32         /** Name of the category, normalized to DB-key form */
  33         private $mName = null;
  34         private $mID = null;
  35         /**
  36          * Category page title
  37          * @var Title
  38          */
  39         private $mTitle = null;
  40         /** Counts of membership (cat_pages, cat_subcats, cat_files) */
  41         private $mPages = null, $mSubcats = null, $mFiles = null;
  42
  43         private function __construct() {
  44         }
  45
  46         /**
  47          * Set up all member variables using a database query.
  48          * @throws MWException
  49          * @return bool True on success, false on failure.
  50          */
  51         protected function initialize() {
  52                 if ( $this->mName === null && $this->mID === null ) {
  53                         throw new MWException( __METHOD__ . ' has both names and IDs null' );
  54                 } elseif ( $this->mID === null ) {
  55                         $where = [ 'cat_title' => $this->mName ];
  56                 } elseif ( $this->mName === null ) {
  57                         $where = [ 'cat_id' => $this->mID ];
  58                 } else {
  59                         # Already initialized
  60                         return true;
  61                 }
  62
  63                 $dbr = wfGetDB( DB_REPLICA );
  64                 $row = $dbr->selectRow(
  65                         'category',
  66                         [ 'cat_id', 'cat_title', 'cat_pages', 'cat_subcats', 'cat_files' ],
  67                         $where,
  68                         __METHOD__
  69                 );
  70
  71                 if ( !$row ) {
  72                         # Okay, there were no contents.  Nothing to initialize.
  73                         if ( $this->mTitle ) {
  74                                 # If there is a title object but no record in the category table,
  75                                 # treat this as an empty category.
  76                                 $this->mID = false;
  77                                 $this->mName = $this->mTitle->getDBkey();
  78                                 $this->mPages = 0;
  79                                 $this->mSubcats = 0;
  80                                 $this->mFiles = 0;
  81
  82                                 # If the title exists, call refreshCounts to add a row for it.
  83                                 if ( $this->mTitle->exists() ) {
  84                                         DeferredUpdates::addCallableUpdate( [ $this, 'refreshCounts' ] );
  85                                 }
  86
  87                                 return true;
  88                         } else {
  89                                 return false; # Fail
  90                         }
  91                 }
  92
  93                 $this->mID = $row->cat_id;
  94                 $this->mName = $row->cat_title;
  95                 $this->mPages = $row->cat_pages;
  96                 $this->mSubcats = $row->cat_subcats;
  97                 $this->mFiles = $row->cat_files;
  98
  99                 # (T15683) If the count is negative, then 1) it's obviously wrong
 100                 # and should not be kept, and 2) we *probably* don't have to scan many
 101                 # rows to obtain the correct figure, so let's risk a one-time recount.
 102                 if ( $this->mPages < 0 || $this->mSubcats < 0 || $this->mFiles < 0 ) {
 103                         $this->mPages = max( $this->mPages, 0 );
 104                         $this->mSubcats = max( $this->mSubcats, 0 );
 105                         $this->mFiles = max( $this->mFiles, 0 );
 106
 107                         DeferredUpdates::addCallableUpdate( [ $this, 'refreshCounts' ] );
 108                 }
 109
 110                 return true;
 111         }
 112
 113         /**
 114          * Factory function.
 115          *
 116          * @param array $name A category name (no "Category:" prefix).  It need
 117          *   not be normalized, with spaces replaced by underscores.
 118          * @return mixed Category, or false on a totally invalid name
 119          */
 120         public static function newFromName( $name ) {
 121                 $cat = new self();
 122                 $title = Title::makeTitleSafe( NS_CATEGORY, $name );
 123
 124                 if ( !is_object( $title ) ) {
 125                         return false;
 126                 }
 127
 128                 $cat->mTitle = $title;
 129                 $cat->mName = $title->getDBkey();
 130
 131                 return $cat;
 132         }
 133
 134         /**
 135          * Factory function.
 136          *
 137          * @param Title $title Title for the category page
 138          * @return Category|bool On a totally invalid name
 139          */
 140         public static function newFromTitle( $title ) {
 141                 $cat = new self();
 142
 143                 $cat->mTitle = $title;
 144                 $cat->mName = $title->getDBkey();
 145
 146                 return $cat;
 147         }
 148
 149         /**
 150          * Factory function.
 151          *
 152          * @param int $id A category id
 153          * @return Category
 154          */
 155         public static function newFromID( $id ) {
 156                 $cat = new self();
 157                 $cat->mID = intval( $id );
 158                 return $cat;
 159         }
 160
 161         /**
 162          * Factory function, for constructing a Category object from a result set
 163          *
 164          * @param object $row Result set row, must contain the cat_xxx fields. If the
 165          *   fields are null, the resulting Category object will represent an empty
 166          *   category if a title object was given. If the fields are null and no
 167          *   title was given, this method fails and returns false.
 168          * @param Title $title Optional title object for the category represented by
 169          *   the given row. May be provided if it is already known, to avoid having
 170          *   to re-create a title object later.
 171          * @return Category|false
 172          */
 173         public static function newFromRow( $row, $title = null ) {
 174                 $cat = new self();
 175                 $cat->mTitle = $title;
 176
 177                 # NOTE: the row often results from a LEFT JOIN on categorylinks. This may result in
 178                 #       all the cat_xxx fields being null, if the category page exists, but nothing
 179                 #       was ever added to the category. This case should be treated link an empty
 180                 #       category, if possible.
 181
 182                 if ( $row->cat_title === null ) {
 183                         if ( $title === null ) {
 184                                 # the name is probably somewhere in the row, for example as page_title,
 185                                 # but we can't know that here...
 186                                 return false;
 187                         } else {
 188                                 # if we have a title object, fetch the category name from there
 189                                 $cat->mName = $title->getDBkey();
 190                         }
 191
 192                         $cat->mID = false;
 193                         $cat->mSubcats = 0;
 194                         $cat->mPages = 0;
 195                         $cat->mFiles = 0;
 196                 } else {
 197                         $cat->mName = $row->cat_title;
 198                         $cat->mID = $row->cat_id;
 199                         $cat->mSubcats = $row->cat_subcats;
 200                         $cat->mPages = $row->cat_pages;
 201                         $cat->mFiles = $row->cat_files;
 202                 }
 203
 204                 return $cat;
 205         }
 206
 207         /**
 208          * @return mixed DB key name, or false on failure
 209          */
 210         public function getName() {
 211                 return $this->getX( 'mName' );
 212         }
 213
 214         /**
 215          * @return mixed Category ID, or false on failure
 216          */
 217         public function getID() {
 218                 return $this->getX( 'mID' );
 219         }
 220
 221         /**
 222          * @return mixed Total number of member pages, or false on failure
 223          */
 224         public function getPageCount() {
 225                 return $this->getX( 'mPages' );
 226         }
 227
 228         /**
 229          * @return mixed Number of subcategories, or false on failure
 230          */
 231         public function getSubcatCount() {
 232                 return $this->getX( 'mSubcats' );
 233         }
 234
 235         /**
 236          * @return mixed Number of member files, or false on failure
 237          */
 238         public function getFileCount() {
 239                 return $this->getX( 'mFiles' );
 240         }
 241
 242         /**
 243          * @return Title|bool Title for this category, or false on failure.
 244          */
 245         public function getTitle() {
 246                 if ( $this->mTitle ) {
 247                         return $this->mTitle;
 248                 }
 249
 250                 if ( !$this->initialize() ) {
 251                         return false;
 252                 }
 253
 254                 $this->mTitle = Title::makeTitleSafe( NS_CATEGORY, $this->mName );
 255                 return $this->mTitle;
 256         }
 257
 258         /**
 259          * Fetch a TitleArray of up to $limit category members, beginning after the
 260          * category sort key $offset.
 261          * @param int $limit
 262          * @param string $offset
 263          * @return TitleArray TitleArray object for category members.
 264          */
 265         public function getMembers( $limit = false, $offset = '' ) {
 266
 267                 $dbr = wfGetDB( DB_REPLICA );
 268
 269                 $conds = [ 'cl_to' => $this->getName(), 'cl_from = page_id' ];
 270                 $options = [ 'ORDER BY' => 'cl_sortkey' ];
 271
 272                 if ( $limit ) {
 273                         $options['LIMIT'] = $limit;
 274                 }
 275
 276                 if ( $offset !== '' ) {
 277                         $conds[] = 'cl_sortkey > ' . $dbr->addQuotes( $offset );
 278                 }
 279
 280                 $result = TitleArray::newFromResult(
 281                         $dbr->select(
 282                                 [ 'page', 'categorylinks' ],
 283                                 [ 'page_id', 'page_namespace', 'page_title', 'page_len',
 284                                         'page_is_redirect', 'page_latest' ],
 285                                 $conds,
 286                                 __METHOD__,
 287                                 $options
 288                         )
 289                 );
 290
 291                 return $result;
 292         }
 293
 294         /**
 295          * Generic accessor
 296          * @param string $key
 297          * @return bool
 298          */
 299         private function getX( $key ) {
 300                 if ( !$this->initialize() ) {
 301                         return false;
 302                 }
 303                 return $this->{$key};
 304         }
 305
 306         /**
 307          * Refresh the counts for this category.
 308          *
 309          * @return bool True on success, false on failure
 310          */
 311         public function refreshCounts() {
 312                 if ( wfReadOnly() ) {
 313                         return false;
 314                 }
 315
 316                 # If we have just a category name, find out whether there is an
 317                 # existing row. Or if we have just an ID, get the name, because
 318                 # that's what categorylinks uses.
 319                 if ( !$this->initialize() ) {
 320                         return false;
 321                 }
 322
 323                 $dbw = wfGetDB( DB_MASTER );
 324                 $dbw->startAtomic( __METHOD__ );
 325
 326                 $cond1 = $dbw->conditional( [ 'page_namespace' => NS_CATEGORY ], 1, 'NULL' );
 327                 $cond2 = $dbw->conditional( [ 'page_namespace' => NS_FILE ], 1, 'NULL' );
 328                 $result = $dbw->selectRow(
 329                         [ 'categorylinks', 'page' ],
 330                         [ 'pages' => 'COUNT(*)',
 331                                 'subcats' => "COUNT($cond1)",
 332                                 'files' => "COUNT($cond2)"
 333                         ],
 334                         [ 'cl_to' => $this->mName, 'page_id = cl_from' ],
 335                         __METHOD__,
 336                         [ 'LOCK IN SHARE MODE' ]
 337                 );
 338
 339                 $shouldExist = $result->pages > 0 || $this->getTitle()->exists();
 340
 341                 if ( $this->mID ) {
 342                         if ( $shouldExist ) {
 343                                 # The category row already exists, so do a plain UPDATE instead
 344                                 # of INSERT...ON DUPLICATE KEY UPDATE to avoid creating a gap
 345                                 # in the cat_id sequence. The row may or may not be "affected".
 346                                 $dbw->update(
 347                                         'category',
 348                                         [
 349                                                 'cat_pages' => $result->pages,
 350                                                 'cat_subcats' => $result->subcats,
 351                                                 'cat_files' => $result->files
 352                                         ],
 353                                         [ 'cat_title' => $this->mName ],
 354                                         __METHOD__
 355                                 );
 356                         } else {
 357                                 # The category is empty and has no description page, delete it
 358                                 $dbw->delete(
 359                                         'category',
 360                                         [ 'cat_title' => $this->mName ],
 361                                         __METHOD__
 362                                 );
 363                                 $this->mID = false;
 364                         }
 365                 } elseif ( $shouldExist ) {
 366                         # The category row doesn't exist but should, so create it. Use
 367                         # upsert in case of races.
 368                         $dbw->upsert(
 369                                 'category',
 370                                 [
 371                                         'cat_title' => $this->mName,
 372                                         'cat_pages' => $result->pages,
 373                                         'cat_subcats' => $result->subcats,
 374                                         'cat_files' => $result->files
 375                                 ],
 376                                 [ 'cat_title' ],
 377                                 [
 378                                         'cat_pages' => $result->pages,
 379                                         'cat_subcats' => $result->subcats,
 380                                         'cat_files' => $result->files
 381                                 ],
 382                                 __METHOD__
 383                         );
 384                         // @todo: Should we update $this->mID here? Or not since Category
 385                         // objects tend to be short lived enough to not matter?
 386                 }
 387
 388                 $dbw->endAtomic( __METHOD__ );
 389
 390                 # Now we should update our local counts.
 391                 $this->mPages = $result->pages;
 392                 $this->mSubcats = $result->subcats;
 393                 $this->mFiles = $result->files;
 394
 395                 return true;
 396         }
 397 }