includes/DBDataObject.php

   1 <?php
   2
   3 /**
   4  * Abstract base class for representing objects that are stored in some DB table.
   5  * This is basically an ORM-like wrapper around rows in database tables that
   6  * aims to be both simple and very flexible. It is centered around an associative
   7  * array of fields and various methods to do common interaction with the database.
   8  *
   9  * These methods must be implemented in deriving classes:
  10  * * getFieldTypes
  11  *
  12  * These methods are likely candidates for overriding:
  13  * * getDefaults
  14  * * remove
  15  * * insert
  16  * * saveExisting
  17  * * loadSummaryFields
  18  * * getSummaryFields
  19  *
  20  * Deriving classes must register their table and field prefix in $wgDBDataObjects.
  21  * Syntax: $wgDBDataObjects['DrivingClassName'] = array( 'table' => 'table_name', 'prefix' => 'fieldprefix_' );
  22  * Example: $wgDBDataObjects['EPOrg'] = array( 'table' => 'ep_orgs', 'prefix' => 'org_' );
  23  *
  24  * Main instance methods:
  25  * * getField(s)
  26  * * setField(s)
  27  * * save
  28  * * remove
  29  *
  30  * Main static methods:
  31  * * select
  32  * * update
  33  * * delete
  34  * * count
  35  * * has
  36  * * selectRow
  37  * * selectFields
  38  * * selectFieldsRow
  39  *
  40  * @since 1.20
  41  *
  42  * @file DBDataObject.php
  43  *
  44  * @licence GNU GPL v3 or later
  45  * @author Jeroen De Dauw < jeroendedauw@gmail.com >
  46  */
  47 abstract class DBDataObject {
  48
  49         /**
  50          * The fields of the object.
  51          * field name (w/o prefix) => value
  52          *
  53          * @since 1.20
  54          * @var array
  55          */
  56         protected $fields = array( 'id' => null );
  57
  58         /**
  59          * If the object should update summaries of linked items when changed.
  60          * For example, update the course_count field in universities when a course in courses is deleted.
  61          * Settings this to false can prevent needless updating work in situations
  62          * such as deleting a university, which will then delete all it's courses.
  63          *
  64          * @since 1.20
  65          * @var bool
  66          */
  67         protected $updateSummaries = true;
  68
  69         /**
  70          * Indicates if the object is in summary mode.
  71          * This mode indicates that only summary fields got updated,
  72          * which allows for optimizations.
  73          *
  74          * @since 1.20
  75          * @var bool
  76          */
  77         protected $inSummaryMode = false;
  78
  79
  80         /**
  81          * The database connection to use for read operations.
  82          * Can be changed via @see setReadDb.
  83          *
  84          * @since 0.2
  85          * @var integer DB_ enum
  86          */
  87         protected static $readDb = DB_SLAVE;
  88
  89         /**
  90          * Returns the name of the database table objects of this type are stored in.
  91          *
  92          * @since 1.20
  93          *
  94          * @throws MWException
  95          * @return string
  96          */
  97         public static function getDBTable() {
  98                 global $wgDBDataObjects;
  99                 if ( array_key_exists( get_called_class(), $wgDBDataObjects ) ) {
 100                         return $wgDBDataObjects[get_called_class()]['table'];
 101                 }
 102                 else {
 103                         throw new MWException( 'Class "' . get_called_class() . '" not found in $wgDBDataObjects' );
 104                 }
 105         }
 106
 107         /**
 108          * Gets the db field prefix.
 109          *
 110          * @since 1.20
 111          *
 112          * @throws MWException
 113          * @return string
 114          */
 115         protected static function getFieldPrefix() {
 116                 global $wgDBDataObjects;
 117                 if ( array_key_exists( get_called_class(), $wgDBDataObjects ) ) {
 118                         return $wgDBDataObjects[get_called_class()]['prefix'];
 119                 }
 120                 else {
 121                         throw new MWException( 'Class "' . get_called_class() . '" not found in $wgDBDataObjects' );
 122                 }
 123         }
 124
 125         /**
 126          * Returns an array with the fields and their types this object contains.
 127          * This corresponds directly to the fields in the database, without prefix.
 128          *
 129          * field name => type
 130          *
 131          * Allowed types:
 132          * * id
 133          * * str
 134          * * int
 135          * * float
 136          * * bool
 137          * * array
 138          *
 139          * @since 1.20
 140          *
 141          * @throws MWException
 142          * @return array
 143          */
 144         protected static function getFieldTypes() {
 145                 throw new MWException( 'Class did not implement getFieldTypes' );
 146         }
 147
 148         /**
 149          * Returns a list of default field values.
 150          * field name => field value
 151          *
 152          * @since 1.20
 153          *
 154          * @return array
 155          */
 156         public static function getDefaults() {
 157                 return array();
 158         }
 159
 160         /**
 161          * Returns a list of the summary fields.
 162          * These are fields that cache computed values, such as the amount of linked objects of $type.
 163          * This is relevant as one might not want to do actions such as log changes when these get updated.
 164          *
 165          * @since 1.20
 166          *
 167          * @return array
 168          */
 169         public static function getSummaryFields() {
 170                 return array();
 171         }
 172
 173         /**
 174          * Constructor.
 175          *
 176          * @since 1.20
 177          *
 178          * @param array|null $fields
 179          * @param boolean $loadDefaults
 180          */
 181         public function __construct( $fields = null, $loadDefaults = false ) {
 182                 if ( !is_array( $fields ) ) {
 183                         $fields = array();
 184                 }
 185
 186                 if ( $loadDefaults ) {
 187                         $fields = array_merge( $this->getDefaults(), $fields );
 188                 }
 189
 190                 $this->setFields( $fields );
 191         }
 192
 193         /**
 194          * Load the specified fields from the database.
 195          *
 196          * @since 1.20
 197          *
 198          * @param array|null $fields
 199          * @param boolean $override
 200          * @param boolean $skipLoaded
 201          *
 202          * @return Success indicator
 203          */
 204         public function loadFields( $fields = null, $override = true, $skipLoaded = false ) {
 205                 if ( is_null( $this->getId() ) ) {
 206                         return false;
 207                 }
 208
 209                 if ( is_null( $fields ) ) {
 210                         $fields = array_keys( $this->getFieldTypes() );
 211                 }
 212
 213                 if ( $skipLoaded ) {
 214                         $fields = array_diff( $fields, array_keys( $this->fields ) );
 215                 }
 216
 217                 if ( count( $fields ) > 0 ) {
 218                         $results = $this->rawSelect(
 219                                 $this->getPrefixedFields( $fields ),
 220                                 array( $this->getPrefixedField( 'id' ) => $this->getId() ),
 221                                 array( 'LIMIT' => 1 )
 222                         );
 223
 224                         foreach ( $results as $result ) {
 225                                 $this->setFields( $this->getFieldsFromDBResult( $result ), $override );
 226                                 return true;
 227                         }
 228
 229                         return false;
 230                 }
 231
 232                 return true;
 233         }
 234
 235         /**
 236          * Gets the value of a field.
 237          *
 238          * @since 1.20
 239          *
 240          * @param string $name
 241          * @param mixed $default
 242          *
 243          * @throws MWException
 244          * @return mixed
 245          */
 246         public function getField( $name, $default = null ) {
 247                 if ( $this->hasField( $name ) ) {
 248                         return $this->fields[$name];
 249                 } elseif ( !is_null( $default ) ) {
 250                         return $default;
 251                 } else {
 252                         throw new MWException( 'Attempted to get not-set field ' . $name );
 253                 }
 254         }
 255
 256         /**
 257          * Gets the value of a field but first loads it if not done so already.
 258          *
 259          * @since 1.20
 260          *
 261          * @param string$name
 262          *
 263          * @return mixed
 264          */
 265         public function loadAndGetField( $name ) {
 266                 if ( !$this->hasField( $name ) ) {
 267                         $this->loadFields( array( $name ) );
 268                 }
 269
 270                 return $this->getField( $name );
 271         }
 272
 273         /**
 274          * Remove a field.
 275          *
 276          * @since 1.20
 277          *
 278          * @param string $name
 279          */
 280         public function removeField( $name ) {
 281                 unset( $this->fields[$name] );
 282         }
 283
 284         /**
 285          * Returns the objects database id.
 286          *
 287          * @since 1.20
 288          *
 289          * @return integer|null
 290          */
 291         public function getId() {
 292                 return $this->getField( 'id' );
 293         }
 294
 295         /**
 296          * Sets the objects database id.
 297          *
 298          * @since 1.20
 299          *
 300          * @param integer|null $id
 301          */
 302         public function setId( $id ) {
 303                 return $this->setField( 'id', $id );
 304         }
 305
 306         /**
 307          * Gets if a certain field is set.
 308          *
 309          * @since 1.20
 310          *
 311          * @param string $name
 312          *
 313          * @return boolean
 314          */
 315         public function hasField( $name ) {
 316                 return array_key_exists( $name, $this->fields );
 317         }
 318
 319         /**
 320          * Gets if the id field is set.
 321          *
 322          * @since 1.20
 323          *
 324          * @return boolean
 325          */
 326         public function hasIdField() {
 327                 return $this->hasField( 'id' )
 328                         && !is_null( $this->getField( 'id' ) );
 329         }
 330
 331         /**
 332          * Sets multiple fields.
 333          *
 334          * @since 1.20
 335          *
 336          * @param array $fields The fields to set
 337          * @param boolean $override Override already set fields with the provided values?
 338          */
 339         public function setFields( array $fields, $override = true ) {
 340                 foreach ( $fields as $name => $value ) {
 341                         if ( $override || !$this->hasField( $name ) ) {
 342                                 $this->setField( $name, $value );
 343                         }
 344                 }
 345         }
 346
 347         /**
 348          * Gets the fields => values to write to the table.
 349          *
 350          * @since 1.20
 351          *
 352          * @return array
 353          */
 354         protected function getWriteValues() {
 355                 $values = array();
 356
 357                 foreach ( $this->getFieldTypes() as $name => $type ) {
 358                         if ( array_key_exists( $name, $this->fields ) ) {
 359                                 $value = $this->fields[$name];
 360
 361                                 switch ( $type ) {
 362                                         case 'array':
 363                                                 $value = (array)$value;
 364                                         case 'blob':
 365                                                 $value = serialize( $value );
 366                                 }
 367
 368                                 $values[$this->getFieldPrefix() . $name] = $value;
 369                         }
 370                 }
 371
 372                 return $values;
 373         }
 374
 375         /**
 376          * Serializes the object to an associative array which
 377          * can then easily be converted into JSON or similar.
 378          *
 379          * @since 1.20
 380          *
 381          * @param null|array $fields
 382          * @param boolean $incNullId
 383          *
 384          * @return array
 385          */
 386         public function toArray( $fields = null, $incNullId = false ) {
 387                 $data = array();
 388                 $setFields = array();
 389
 390                 if ( !is_array( $fields ) ) {
 391                         $setFields = $this->getSetFieldNames();
 392                 } else {
 393                         foreach ( $fields as $field ) {
 394                                 if ( $this->hasField( $field ) ) {
 395                                         $setFields[] = $field;
 396                                 }
 397                         }
 398                 }
 399
 400                 foreach ( $setFields as $field ) {
 401                         if ( $incNullId || $field != 'id' || $this->hasIdField() ) {
 402                                 $data[$field] = $this->getField( $field );
 403                         }
 404                 }
 405
 406                 return $data;
 407         }
 408
 409         /**
 410          * Load the default values, via getDefaults.
 411          *
 412          *  @since 1.20
 413          *
 414          * @param boolean $override
 415          */
 416         public function loadDefaults( $override = true ) {
 417                 $this->setFields( $this->getDefaults(), $override );
 418         }
 419
 420         /**
 421          * Writes the answer to the database, either updating it
 422          * when it already exists, or inserting it when it doesn't.
 423          *
 424          * @since 1.20
 425          *
 426          * @return boolean Success indicator
 427          */
 428         public function save() {
 429                 if ( $this->hasIdField() ) {
 430                         return $this->saveExisting();
 431                 } else {
 432                         return $this->insert();
 433                 }
 434         }
 435
 436         /**
 437          * Updates the object in the database.
 438          *
 439          * @since 1.20
 440          *
 441          * @return boolean Success indicator
 442          */
 443         protected function saveExisting() {
 444                 $dbw = wfGetDB( DB_MASTER );
 445
 446                 $success = $dbw->update(
 447                         $this->getDBTable(),
 448                         $this->getWriteValues(),
 449                         array( $this->getFieldPrefix() . 'id' => $this->getId() ),
 450                         __METHOD__
 451                 );
 452
 453                 return $success;
 454         }
 455
 456         /**
 457          * Inserts the object into the database.
 458          *
 459          * @since 1.20
 460          *
 461          * @return boolean Success indicator
 462          */
 463         protected function insert() {
 464                 $dbw = wfGetDB( DB_MASTER );
 465
 466                 $result = $dbw->insert(
 467                         $this->getDBTable(),
 468                         $this->getWriteValues(),
 469                         __METHOD__,
 470                         array( 'IGNORE' )
 471                 );
 472
 473                 if ( $result ) {
 474                         $this->setField( 'id', $dbw->insertId() );
 475                 }
 476
 477                 return $result;
 478         }
 479
 480         /**
 481          * Removes the object from the database.
 482          *
 483          * @since 1.20
 484          *
 485          * @return boolean Success indicator
 486          */
 487         public function remove() {
 488                 $this->beforeRemove();
 489
 490                 $success = static::delete( array( 'id' => $this->getId() ) );
 491
 492                 if ( $success ) {
 493                         $this->onRemoved();
 494                 }
 495
 496                 return $success;
 497         }
 498
 499         /**
 500          * Gets called before an object is removed from the database.
 501          *
 502          * @since 1.20
 503          */
 504         protected function beforeRemove() {
 505                 $this->loadFields( $this->getBeforeRemoveFields(), false, true );
 506         }
 507
 508         /**
 509          * Before removal of an object happens, @see beforeRemove gets called.
 510          * This method loads the fields of which the names have been returned by this one (or all fields if null is returned).
 511          * This allows for loading info needed after removal to get rid of linked data and the like.
 512          *
 513          * @since 1.20
 514          *
 515          * @return array|null
 516          */
 517         protected function getBeforeRemoveFields() {
 518                 return array();
 519         }
 520
 521         /**
 522          * Gets called after successfull removal.
 523          * Can be overriden to get rid of linked data.
 524          *
 525          * @since 1.20
 526          */
 527         protected function onRemoved() {
 528                 $this->setField( 'id', null );
 529         }
 530
 531         /**
 532          * Return the names and values of the fields.
 533          *
 534          * @since 1.20
 535          *
 536          * @return array
 537          */
 538         public function getFields() {
 539                 return $this->fields;
 540         }
 541
 542         /**
 543          * Return the names of the fields.
 544          *
 545          * @since 1.20
 546          *
 547          * @return array
 548          */
 549         public function getSetFieldNames() {
 550                 return array_keys( $this->fields );
 551         }
 552
 553         /**
 554          * Sets the value of a field.
 555          * Strings can be provided for other types,
 556          * so this method can be called from unserialization handlers.
 557          *
 558          * @since 1.20
 559          *
 560          * @param string $name
 561          * @param mixed $value
 562          *
 563          * @throws MWException
 564          */
 565         public function setField( $name, $value ) {
 566                 $fields = $this->getFieldTypes();
 567
 568                 if ( array_key_exists( $name, $fields ) ) {
 569                         switch ( $fields[$name] ) {
 570                                 case 'int':
 571                                         $value = (int)$value;
 572                                         break;
 573                                 case 'float':
 574                                         $value = (float)$value;
 575                                         break;
 576                                 case 'bool':
 577                                         if ( is_string( $value ) ) {
 578                                                 $value = $value !== '0';
 579                                         } elseif ( is_int( $value ) ) {
 580                                                 $value = $value !== 0;
 581                                         }
 582                                         break;
 583                                 case 'array':
 584                                         if ( is_string( $value ) ) {
 585                                                 $value = unserialize( $value );
 586                                         }
 587
 588                                         if ( !is_array( $value ) ) {
 589                                                 $value = array();
 590                                         }
 591                                         break;
 592                                 case 'blob':
 593                                         if ( is_string( $value ) ) {
 594                                                 $value = unserialize( $value );
 595                                         }
 596                                         break;
 597                                 case 'id':
 598                                         if ( is_string( $value ) ) {
 599                                                 $value = (int)$value;
 600                                         }
 601                                         break;
 602                         }
 603
 604                         $this->fields[$name] = $value;
 605                 } else {
 606                         throw new MWException( 'Attempted to set unknown field ' . $name );
 607                 }
 608         }
 609
 610         /**
 611          * Get a new instance of the class from an array.
 612          *
 613          * @since 1.20
 614          *
 615          * @param array $data
 616          * @param boolean $loadDefaults
 617          *
 618          * @return DBDataObject
 619          */
 620         public static function newFromArray( array $data, $loadDefaults = false ) {
 621                 return new static( $data, $loadDefaults );
 622         }
 623
 624         /**
 625          * Get the database type used for read operations.
 626          *
 627          * @since 0.2
 628          * @return integer DB_ enum
 629          */
 630         public static function getReadDb() {
 631                 return self::$readDb;
 632         }
 633
 634         /**
 635          * Set the database type to use for read operations.
 636          *
 637          * @param integer $db
 638          *
 639          * @since 0.2
 640          */
 641         public static function setReadDb( $db ) {
 642                 self::$readDb = $db;
 643         }
 644
 645         /**
 646          * Gets if the object can take a certain field.
 647          *
 648          * @since 1.20
 649          *
 650          * @param string $name
 651          *
 652          * @return boolean
 653          */
 654         public static function canHasField( $name ) {
 655                 return array_key_exists( $name, static::getFieldTypes() );
 656         }
 657
 658         /**
 659          * Takes in a field or array of fields and returns an
 660          * array with their prefixed versions, ready for db usage.
 661          *
 662          * @since 1.20
 663          *
 664          * @param array|string $fields
 665          *
 666          * @return array
 667          */
 668         public static function getPrefixedFields( array $fields ) {
 669                 foreach ( $fields as &$field ) {
 670                         $field = static::getPrefixedField( $field );
 671                 }
 672
 673                 return $fields;
 674         }
 675
 676         /**
 677          * Takes in a field and returns an it's prefixed version, ready for db usage.
 678          * If the field needs to be prefixed for another table, provide an array in the form
 679          * array( 'tablename', 'fieldname' )
 680          * Where table name is registered in $wgDBDataObjects.
 681          *
 682          * @since 1.20
 683          *
 684          * @param string|array $field
 685          *
 686          * @return string
 687          * @throws MWException
 688          */
 689         public static function getPrefixedField( $field ) {
 690                 static $prefixes = false;
 691
 692                 if ( $prefixes === false ) {
 693                         foreach ( $GLOBALS['wgDBDataObjects'] as $classInfo ) {
 694                                 $prefixes[$classInfo['table']] = $classInfo['prefix'];
 695                         }
 696                 }
 697
 698                 if ( is_array( $field ) && count( $field ) > 1 ) {
 699                         if ( array_key_exists( $field[0], $prefixes ) ) {
 700                                 $prefix = $prefixes[$field[0]];
 701                                 $field = $field[1];
 702                         }
 703                         else {
 704                                 throw new MWException( 'Tried to prefix field with unknown table "' . $field[0] . '"' );
 705                         }
 706                 }
 707                 else {
 708                         $prefix = static::getFieldPrefix();
 709                 }
 710
 711                 return $prefix . $field;
 712         }
 713
 714         /**
 715          * Takes in an associative array with field names as keys and
 716          * their values as value. The field names are prefixed with the
 717          * db field prefix.
 718          *
 719          * Field names can also be provided as an array with as first element a table name, such as
 720          * $conditions = array(
 721          *       array( array( 'tablename', 'fieldname' ), $value ),
 722          * );
 723          *
 724          * @since 1.20
 725          *
 726          * @param array $values
 727          *
 728          * @return array
 729          */
 730         public static function getPrefixedValues( array $values ) {
 731                 $prefixedValues = array();
 732
 733                 foreach ( $values as $field => $value ) {
 734                         if ( is_integer( $field ) ) {
 735                                 if ( is_array( $value ) ) {
 736                                         $field = $value[0];
 737                                         $value = $value[1];
 738                                 }
 739                                 else {
 740                                         $value = explode( ' ', $value, 2 );
 741                                         $value[0] = static::getPrefixedField( $value[0] );
 742                                         $prefixedValues[] = implode( ' ', $value );
 743                                         continue;
 744                                 }
 745                         }
 746
 747                         $prefixedValues[static::getPrefixedField( $field )] = $value;
 748                 }
 749
 750                 return $prefixedValues;
 751         }
 752
 753         /**
 754          * Get an array with fields from a database result,
 755          * that can be fed directly to the constructor or
 756          * to setFields.
 757          *
 758          * @since 1.20
 759          *
 760          * @param object $result
 761          *
 762          * @return array
 763          */
 764         public static function getFieldsFromDBResult( $result ) {
 765                 $result = (array)$result;
 766                 return array_combine(
 767                         static::unprefixFieldNames( array_keys( $result ) ),
 768                         array_values( $result )
 769                 );
 770         }
 771
 772         /**
 773          * Takes a field name with prefix and returns the unprefixed equivalent.
 774          *
 775          * @since 1.20
 776          *
 777          * @param string $fieldName
 778          *
 779          * @return string
 780          */
 781         public static function unprefixFieldName( $fieldName ) {
 782                 return substr( $fieldName, strlen( static::getFieldPrefix() ) );
 783         }
 784
 785         /**
 786          * Takes an array of field names with prefix and returns the unprefixed equivalent.
 787          *
 788          * @since 1.20
 789          *
 790          * @param array $fieldNames
 791          *
 792          * @return array
 793          */
 794         public static function unprefixFieldNames( array $fieldNames ) {
 795                 return array_map( 'static::unprefixFieldName', $fieldNames );
 796         }
 797
 798         /**
 799          * Get a new instance of the class from a database result.
 800          *
 801          * @since 1.20
 802          *
 803          * @param stdClass $result
 804          *
 805          * @return DBDataObject
 806          */
 807         public static function newFromDBResult( stdClass $result ) {
 808                 return static::newFromArray( static::getFieldsFromDBResult( $result ) );
 809         }
 810
 811         /**
 812          * Removes the object from the database.
 813          *
 814          * @since 1.20
 815          *
 816          * @param array $conditions
 817          *
 818          * @return boolean Success indicator
 819          */
 820         public static function delete( array $conditions ) {
 821                 return wfGetDB( DB_MASTER )->delete(
 822                         static::getDBTable(),
 823                         static::getPrefixedValues( $conditions )
 824                 );
 825         }
 826
 827         /**
 828          * Add an amount (can be negative) to the specified field (needs to be numeric).
 829          *
 830          * @since 1.20
 831          *
 832          * @param string $field
 833          * @param integer $amount
 834          *
 835          * @return boolean Success indicator
 836          */
 837         public static function addToField( $field, $amount ) {
 838                 if ( $amount == 0 ) {
 839                         return true;
 840                 }
 841
 842                 if ( !static::hasIdField() ) {
 843                         return false;
 844                 }
 845
 846                 $absoluteAmount = abs( $amount );
 847                 $isNegative = $amount < 0;
 848
 849                 $dbw = wfGetDB( DB_MASTER );
 850
 851                 $fullField = static::getPrefixedField( $field );
 852
 853                 $success = $dbw->update(
 854                         static::getDBTable(),
 855                         array( "$fullField=$fullField" . ( $isNegative ? '-' : '+' ) . $absoluteAmount ),
 856                         array( static::getPrefixedField( 'id' ) => static::getId() ),
 857                         __METHOD__
 858                 );
 859
 860                 if ( $success && static::hasField( $field ) ) {
 861                         static::setField( $field, static::getField( $field ) + $amount );
 862                 }
 863
 864                 return $success;
 865         }
 866
 867         /**
 868          * Selects the the specified fields of the records matching the provided
 869          * conditions and returns them as DBDataObject. Field names get prefixed.
 870          *
 871          * @since 1.20
 872          *
 873          * @param array|string|null $fields
 874          * @param array $conditions
 875          * @param array $options
 876          * @param array $joinConds
 877          *
 878          * @return array of self
 879          */
 880         public static function select( $fields = null, array $conditions = array(), array $options = array(), array $joinConds = array() ) {
 881                 $result = static::selectFields( $fields, $conditions, $options, $joinConds, false );
 882
 883                 $objects = array();
 884
 885                 foreach ( $result as $record ) {
 886                         $objects[] = static::newFromArray( $record );
 887                 }
 888
 889                 return $objects;
 890         }
 891
 892         /**
 893          * Selects the the specified fields of the records matching the provided
 894          * conditions and returns them as associative arrays.
 895          * Provided field names get prefixed.
 896          * Returned field names will not have a prefix.
 897          *
 898          * When $collapse is true:
 899          * If one field is selected, each item in the result array will be this field.
 900          * If two fields are selected, each item in the result array will have as key
 901          * the first field and as value the second field.
 902          * If more then two fields are selected, each item will be an associative array.
 903          *
 904          * @since 1.20
 905          *
 906          * @param array|string|null $fields
 907          * @param array $conditions
 908          * @param array $options
 909          * @param array $joinConds
 910          * @param boolean $collapse Set to false to always return each result row as associative array.
 911          *
 912          * @return array of array
 913          */
 914         public static function selectFields( $fields = null, array $conditions = array(), array $options = array(), array $joinConds = array(), $collapse = true ) {
 915                 if ( is_null( $fields ) ) {
 916                         $fields = array_keys( static::getFieldTypes() );
 917                 }
 918                 else {
 919                         $fields = (array)$fields;
 920                 }
 921
 922                 $tables = array( static::getDBTable() );
 923                 $joinConds = static::getProcessedJoinConds( $joinConds, $tables );
 924
 925                 $result = static::rawSelect(
 926                         static::getPrefixedFields( $fields ),
 927                         static::getPrefixedValues( $conditions ),
 928                         $options,
 929                         $joinConds,
 930                         $tables
 931                 );
 932
 933                 $objects = array();
 934
 935                 foreach ( $result as $record ) {
 936                         $objects[] = static::getFieldsFromDBResult( $record );
 937                 }
 938
 939                 if ( $collapse ) {
 940                         if ( count( $fields ) === 1 ) {
 941                                 $objects = array_map( function( $object ) { return array_shift( $object ); } , $objects );
 942                         }
 943                         elseif ( count( $fields ) === 2 ) {
 944                                 $o = array();
 945
 946                                 foreach ( $objects as $object ) {
 947                                         $o[array_shift( $object )] = array_shift( $object );
 948                                 }
 949
 950                                 $objects = $o;
 951                         }
 952                 }
 953
 954                 return $objects;
 955         }
 956
 957         /**
 958          * Process the join conditions. This includes prefixing table and field names,
 959          * and adding of needed tables.
 960          *
 961          * @since 1.20
 962          *
 963          * @param array $joinConds Join conditions without prefixes and fields in array rather then string with equals sign.
 964          * @param array $tables List of tables to which the extra needed ones get added.
 965          *
 966          * @return array Join conditions ready to be fed to MediaWikis native select function.
 967          */
 968         protected static function getProcessedJoinConds( array $joinConds, array &$tables ) {
 969                 $conds = array();
 970
 971                 foreach ( $joinConds as $table => $joinCond ) {
 972                         if ( !in_array( $table, $tables ) ) {
 973                                 $tables[] = $table;
 974                         }
 975
 976                         $cond = array( $joinCond[0], array() );
 977
 978                         foreach ( $joinCond[1] as $joinCondPart ) {
 979                                 $parts = array(
 980                                         static::getPrefixedField( $joinCondPart[0] ),
 981                                         static::getPrefixedField( $joinCondPart[1] ),
 982                                 );
 983
 984                                 if ( !in_array( $joinCondPart[0][0], $tables ) ) {
 985                                         $tables[] = $joinCondPart[0][0];
 986                                 }
 987
 988                                 if ( !in_array( $joinCondPart[1][0], $tables ) ) {
 989                                         $tables[] = $joinCondPart[1][0];
 990                                 }
 991
 992                                 $cond[1][] = implode( '=', $parts );
 993                         }
 994
 995                         $conds[$table] = $cond;
 996                 }
 997
 998                 return $conds;
 999         }
1000
1001         /**
1002          * Selects the the specified fields of the first matching record.
1003          * Field names get prefixed.
1004          *
1005          * @since 1.20
1006          *
1007          * @param array|string|null $fields
1008          * @param array $conditions
1009          * @param array $options
1010          * @param array $joinConds
1011          *
1012          * @return EPBObject|false
1013          */
1014         public static function selectRow( $fields = null, array $conditions = array(), array $options = array(), array $joinConds = array() ) {
1015                 $options['LIMIT'] = 1;
1016
1017                 $objects = static::select( $fields, $conditions, $options, $joinConds );
1018
1019                 return count( $objects ) > 0 ? $objects[0] : false;
1020         }
1021
1022         /**
1023          * Selects the the specified fields of the first record matching the provided
1024          * conditions and returns it as an associative array, or false when nothing matches.
1025          * This method makes use of selectFields and expects the same parameters and
1026          * returns the same results (if there are any, if there are none, this method returns false).
1027          * @see DBDataObject::selectFields
1028          *
1029          * @since 1.20
1030          *
1031          * @param array|string|null $fields
1032          * @param array $conditions
1033          * @param array $options
1034          * @param array $joinConds
1035          * @param boolean $collapse Set to false to always return each result row as associative array.
1036          *
1037          * @return mixed|array|false
1038          */
1039         public static function selectFieldsRow( $fields = null, array $conditions = array(), array $options = array(), array $joinConds = array(), $collapse = true ) {
1040                 $options['LIMIT'] = 1;
1041
1042                 $objects = static::selectFields( $fields, $conditions, $options, $joinConds, $collapse );
1043
1044                 return count( $objects ) > 0 ? $objects[0] : false;
1045         }
1046
1047         /**
1048          * Returns if there is at least one record matching the provided conditions.
1049          * Condition field names get prefixed.
1050          *
1051          * @since 1.20
1052          *
1053          * @param array $conditions
1054          *
1055          * @return boolean
1056          */
1057         public static function has( array $conditions = array() ) {
1058                 return static::selectRow( array( 'id' ), $conditions ) !== false;
1059         }
1060
1061         /**
1062          * Returns the amount of matching records.
1063          * Condition field names get prefixed.
1064          *
1065          * @since 1.20
1066          *
1067          * @param array $conditions
1068          * @param array $options
1069          *
1070          * @return integer
1071          */
1072         public static function count( array $conditions = array(), array $options = array() ) {
1073                 $res = static::rawSelect(
1074                         array( 'COUNT(*) AS rowcount' ),
1075                         static::getPrefixedValues( $conditions ),
1076                         $options
1077                 )->fetchObject();
1078
1079                 return $res->rowcount;
1080         }
1081
1082         /**
1083          * Selects the the specified fields of the records matching the provided
1084          * conditions. Field names do NOT get prefixed.
1085          *
1086          * @since 1.20
1087          *
1088          * @param array $fields
1089          * @param array $conditions
1090          * @param array $options
1091          * @param array $joinConds
1092          * @param array $tables
1093          *
1094          * @return ResultWrapper
1095          */
1096         public static function rawSelect( array $fields, array $conditions = array(), array $options = array(), array $joinConds = array(), array $tables = null ) {
1097                 if ( is_null( $tables ) ) {
1098                         $tables = static::getDBTable();
1099                 }
1100
1101                 $dbr = wfGetDB( static::getReadDb() );
1102
1103                 return $dbr->select(
1104                         $tables,
1105                         $fields,
1106                         count( $conditions ) == 0 ? '' : $conditions,
1107                         __METHOD__,
1108                         $options,
1109                         $joinConds
1110                 );
1111         }
1112
1113         /**
1114          * Update the records matching the provided conditions by
1115          * setting the fields that are keys in the $values param to
1116          * their corresponding values.
1117          *
1118          * @since 1.20
1119          *
1120          * @param array $values
1121          * @param array $conditions
1122          *
1123          * @return boolean Success indicator
1124          */
1125         public static function update( array $values, array $conditions = array() ) {
1126                 $dbw = wfGetDB( DB_MASTER );
1127
1128                 return $dbw->update(
1129                         static::getDBTable(),
1130                         static::getPrefixedValues( $values ),
1131                         static::getPrefixedValues( $conditions ),
1132                         __METHOD__
1133                 );
1134         }
1135
1136         /**
1137          * Return the names of the fields.
1138          *
1139          * @since 1.20
1140          *
1141          * @return array
1142          */
1143         public static function getFieldNames() {
1144                 return array_keys( static::getFieldTypes() );
1145         }
1146
1147         /**
1148          * Returns an array with the fields and their descriptions.
1149          *
1150          * field name => field description
1151          *
1152          * @since 1.20
1153          *
1154          * @return array
1155          */
1156         public static function getFieldDescriptions() {
1157                 return array();
1158         }
1159
1160         /**
1161          * Get API parameters for the fields supported by this object.
1162          *
1163          * @since 1.20
1164          *
1165          * @param boolean $requireParams
1166          * @param boolean $setDefaults
1167          *
1168          * @return array
1169          */
1170         public static function getAPIParams( $requireParams = false, $setDefaults = false ) {
1171                 $typeMap = array(
1172                         'id' => 'integer',
1173                         'int' => 'integer',
1174                         'float' => 'NULL',
1175                         'str' => 'string',
1176                         'bool' => 'integer',
1177                         'array' => 'string',
1178                         'blob' => 'string',
1179                 );
1180
1181                 $params = array();
1182                 $defaults = static::getDefaults();
1183
1184                 foreach ( static::getFieldTypes() as $field => $type ) {
1185                         if ( $field == 'id' ) {
1186                                 continue;
1187                         }
1188
1189                         $hasDefault = array_key_exists( $field, $defaults );
1190
1191                         $params[$field] = array(
1192                                 ApiBase::PARAM_TYPE => $typeMap[$type],
1193                                 ApiBase::PARAM_REQUIRED => $requireParams && !$hasDefault
1194                         );
1195
1196                         if ( $type == 'array' ) {
1197                                 $params[$field][ApiBase::PARAM_ISMULTI] = true;
1198                         }
1199
1200                         if ( $setDefaults && $hasDefault ) {
1201                                 $default = is_array( $defaults[$field] ) ? implode( '|', $defaults[$field] ) : $defaults[$field];
1202                                 $params[$field][ApiBase::PARAM_DFLT] = $default;
1203                         }
1204                 }
1205
1206                 return $params;
1207         }
1208
1209         /**
1210          * Computes and updates the values of the summary fields.
1211          *
1212          * @since 1.20
1213          *
1214          * @param array|string|null $summaryFields
1215          */
1216         public function loadSummaryFields( $summaryFields = null ) {
1217
1218         }
1219
1220         /**
1221          * Computes the values of the summary fields of the objects matching the provided conditions.
1222          *
1223          * @since 1.20
1224          *
1225          * @param array|string|null $summaryFields
1226          * @param array $conditions
1227          */
1228         public static function updateSummaryFields( $summaryFields = null, array $conditions = array() ) {
1229                 self::setReadDb( DB_MASTER );
1230
1231                 foreach ( self::select( null, $conditions ) as /* DBDataObject */ $item ) {
1232                         $item->loadSummaryFields( $summaryFields );
1233                         $item->setSummaryMode( true );
1234                         $item->saveExisting();
1235                 }
1236
1237                 self::setReadDb( DB_SLAVE );
1238         }
1239
1240         /**
1241          * Sets the value for the @see $updateSummaries field.
1242          *
1243          * @since 1.20
1244          *
1245          * @param boolean $update
1246          */
1247         public function setUpdateSummaries( $update ) {
1248                 $this->updateSummaries = $update;
1249         }
1250
1251         /**
1252          * Sets the value for the @see $inSummaryMode field.
1253          *
1254          * @since 1.20
1255          *
1256          * @param boolean $update
1257          */
1258         public function setSummaryMode( $summaryMode ) {
1259                 $this->inSummaryMode = $summaryMode;
1260         }
1261
1262         /**
1263          * Return if any fields got changed.
1264          *
1265          * @since 1.20
1266          *
1267          * @param DBDataObject $object
1268          * @param boolean $excludeSummaryFields When set to true, summary field changes are ignored.
1269          *
1270          * @return boolean
1271          */
1272         protected function fieldsChanged( DBDataObject $object, $excludeSummaryFields = false ) {
1273                 foreach ( $this->fields as $name => $value ) {
1274                         $excluded = $excludeSummaryFields && in_array( $name, $this->getSummaryFields() );
1275
1276                         if ( !$excluded && $object->getField( $name ) !== $value ) {
1277                                 return true;
1278                         }
1279                 }
1280
1281                 return false;
1282         }
1283
1284 }