From b206cadcdb589e894f1f1f5b5b07f5665823547a Mon Sep 17 00:00:00 2001
From: Jeroen De Dauw <jeroendedauw@users.mediawiki.org>
Date: Sat, 11 Feb 2012 21:34:01 +0000
Subject: [PATCH] adding DBDataObject class after having some people review it
 and posting on the list. docs can currently be found at
 https://www.mediawiki.org/wiki/User:Jeroen_De_Dauw/DBDataObject

---
 includes/AutoLoader.php   |    1 +
 includes/DBDataObject.php | 1287 +++++++++++++++++++++++++++++++++++++
 2 files changed, 1288 insertions(+)
 create mode 100644 includes/DBDataObject.php

diff --git a/includes/AutoLoader.php b/includes/AutoLoader.php
index a55dd1e3b6..856b3e513e 100644
--- a/includes/AutoLoader.php
+++ b/includes/AutoLoader.php
@@ -50,6 +50,7 @@ $wgAutoloadLocalClasses = array(
 	'Cookie' => 'includes/Cookie.php',
 	'CookieJar' => 'includes/Cookie.php',
 	'CurlHttpRequest' => 'includes/HttpFunctions.php',
+	'DBDataObject' => 'includes/DBDataObject.php',
 	'DeferrableUpdate' => 'includes/DeferredUpdates.php',
 	'DeferredUpdates' => 'includes/DeferredUpdates.php',
 	'DerivativeRequest' => 'includes/WebRequest.php',
diff --git a/includes/DBDataObject.php b/includes/DBDataObject.php
new file mode 100644
index 0000000000..bd1ec28eee
--- /dev/null
+++ b/includes/DBDataObject.php
@@ -0,0 +1,1287 @@
+<?php
+
+/**
+ * Abstract base class for representing objects that are stored in some DB table.
+ * This is basically an ORM-like wrapper around rows in database tables that
+ * aims to be both simple and very flexible. It is centered around an associative
+ * array of fields and various methods to do common interaction with the database.
+ *
+ * These methods must be implemented in deriving classes:
+ * * getFieldTypes
+ *
+ * These methods are likely candidates for overriding:
+ * * getDefaults
+ * * remove
+ * * insert
+ * * saveExisting
+ * * loadSummaryFields
+ * * getSummaryFields
+ *
+ * Deriving classes must register their table and field prefix in $wgDBDataObjects.
+ * Syntax: $wgDBDataObjects['DrivingClassName'] = array( 'table' => 'table_name', 'prefix' => 'fieldprefix_' );
+ * Example: $wgDBDataObjects['EPOrg'] = array( 'table' => 'ep_orgs', 'prefix' => 'org_' );
+ *
+ * Main instance methods:
+ * * getField(s)
+ * * setField(s)
+ * * save
+ * * remove
+ * 
+ * Main static methods:
+ * * select
+ * * update
+ * * delete
+ * * count
+ * * has
+ * * selectRow
+ * * selectFields
+ * * selectFieldsRow
+ *
+ * @since 1.20
+ *
+ * @file DBDataObject.php
+ *
+ * @licence GNU GPL v3 or later
+ * @author Jeroen De Dauw < jeroendedauw@gmail.com >
+ */
+abstract class DBDataObject {
+
+	/**
+	 * The fields of the object.
+	 * field name (w/o prefix) => value
+	 *
+	 * @since 0.1
+	 * @var array
+	 */
+	protected $fields = array( 'id' => null );
+
+	/**
+	 * If the object should update summaries of linked items when changed.
+	 * For example, update the course_count field in universities when a course in courses is deleted.
+	 * Settings this to false can prevent needless updating work in situations
+	 * such as deleting a university, which will then delete all it's courses.
+	 *
+	 * @since 0.1
+	 * @var bool
+	 */
+	protected $updateSummaries = true;
+	
+	/**
+	 * Indicates if the object is in summary mode.
+	 * This mode indicates that only summary fields got updated,
+	 * which allows for optimizations.
+	 *
+	 * @since 0.1
+	 * @var bool
+	 */
+	protected $inSummaryMode = false;
+	
+
+	/**
+	 * The database connection to use for read operations.
+	 * Can be changed via @see setReadDb.
+	 *
+	 * @since 0.2
+	 * @var integer DB_ enum
+	 */
+	protected static $readDb = DB_SLAVE;
+
+	/**
+	 * Returns the name of the database table objects of this type are stored in.
+	 *
+	 * @since 0.1
+	 *
+	 * @throws MWException
+	 * @return string
+	 */
+	public static function getDBTable() {
+		global $wgDBDataObjects;
+		if ( array_key_exists( get_called_class(), $wgDBDataObjects ) ) {
+			return $wgDBDataObjects[get_called_class()]['table'];
+		}
+		else {
+			throw new MWException( 'Class "' . get_called_class() . '" not found in $wgDBDataObjects' );
+		}
+	}
+
+	/**
+	 * Gets the db field prefix.
+	 *
+	 * @since 0.1
+	 *
+	 * @throws MWException
+	 * @return string
+	 */
+	protected static function getFieldPrefix() {
+		global $wgDBDataObjects;
+		if ( array_key_exists( get_called_class(), $wgDBDataObjects ) ) {
+			return $wgDBDataObjects[get_called_class()]['prefix'];
+		}
+		else {
+			throw new MWException( 'Class "' . get_called_class() . '" not found in $wgDBDataObjects' );
+		}
+	}
+
+	/**
+	 * Returns an array with the fields and their types this object contains.
+	 * This corresponds directly to the fields in the database, without prefix.
+	 *
+	 * field name => type
+	 *
+	 * Allowed types:
+	 * * id
+	 * * str
+	 * * int
+	 * * float
+	 * * bool
+	 * * array
+	 *
+	 * @since 0.1
+	 *
+	 * @throws MWException
+	 * @return array
+	 */
+	protected static function getFieldTypes() {
+		throw new MWException( 'Class did not implement getFieldTypes' );
+	}
+
+	/**
+	 * Returns a list of default field values.
+	 * field name => field value
+	 *
+	 * @since 0.1
+	 *
+	 * @return array
+	 */
+	public static function getDefaults() {
+		return array();
+	}
+	
+	/**
+	 * Returns a list of the summary fields.
+	 * These are fields that cache computed values, such as the amount of linked objects of $type.
+	 * This is relevant as one might not want to do actions such as log changes when these get updated.
+	 *
+	 * @since 0.1
+	 *
+	 * @return array
+	 */
+	public static function getSummaryFields() {
+		return array();
+	}
+
+	/**
+	 * Constructor.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array|null $fields
+	 * @param boolean $loadDefaults
+	 */
+	public function __construct( $fields = null, $loadDefaults = false ) {
+		if ( !is_array( $fields ) ) {
+			$fields = array();
+		}
+
+		if ( $loadDefaults ) {
+			$fields = array_merge( $this->getDefaults(), $fields );
+		}
+
+		$this->setFields( $fields );
+	}
+
+	/**
+	 * Load the specified fields from the database.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array|null $fields
+	 * @param boolean $override
+	 * @param boolean $skipLoaded
+	 *
+	 * @return Success indicator
+	 */
+	public function loadFields( $fields = null, $override = true, $skipLoaded = false ) {
+		if ( is_null( $this->getId() ) ) {
+			return false;
+		}
+
+		if ( is_null( $fields ) ) {
+			$fields = array_keys( $this->getFieldTypes() );
+		}
+		
+		if ( $skipLoaded ) {
+			$loadedFields = array_keys( $this->fields );
+			$fields = array_filter( $fields, function( $field ) use ( $loadedFields ) {
+				return !in_array( $field, $loadedFields );
+			} );
+		}
+		
+		if ( count( $fields ) > 0 ) {
+			$results = $this->rawSelect(
+				$this->getPrefixedFields( $fields ),
+				array( $this->getPrefixedField( 'id' ) => $this->getId() ),
+				array( 'LIMIT' => 1 )
+			);
+	
+			foreach ( $results as $result ) {
+				$this->setFields( $this->getFieldsFromDBResult( $result ), $override );
+				return true;
+			}
+	
+			return false;
+		}
+
+		return true;
+	}
+
+	/**
+	 * Gets the value of a field.
+	 *
+	 * @since 0.1
+	 *
+	 * @param string $name
+	 * @param mixed $default
+	 *
+	 * @throws MWException
+	 * @return mixed
+	 */
+	public function getField( $name, $default = null ) {
+		if ( $this->hasField( $name ) ) {
+			return $this->fields[$name];
+		} elseif ( !is_null( $default ) ) {
+			return $default;
+		} else {
+			throw new MWException( 'Attempted to get not-set field ' . $name );
+		}
+	}
+
+	/**
+	 * Gets the value of a field but first loads it if not done so already.
+	 *
+	 * @since 0.1
+	 *
+	 * @param string$name
+	 *
+	 * @return mixed
+	 */
+	public function loadAndGetField( $name ) {
+		if ( !$this->hasField( $name ) ) {
+			$this->loadFields( array( $name ) );
+		}
+
+		return $this->getField( $name );
+	}
+
+	/**
+	 * Remove a field.
+	 *
+	 * @since 0.1
+	 *
+	 * @param string $name
+	 */
+	public function removeField( $name ) {
+		unset( $this->fields[$name] );
+	}
+
+	/**
+	 * Returns the objects database id.
+	 *
+	 * @since 0.1
+	 *
+	 * @return integer|null
+	 */
+	public function getId() {
+		return $this->getField( 'id' );
+	}
+
+	/**
+	 * Sets the objects database id.
+	 *
+	 * @since 0.1
+	 *
+	 * @param integer|null $id
+	 */
+	public function setId( $id ) {
+		return $this->setField( 'id', $id );
+	}
+
+	/**
+	 * Gets if a certain field is set.
+	 *
+	 * @since 0.1
+	 *
+	 * @param string $name
+	 *
+	 * @return boolean
+	 */
+	public function hasField( $name ) {
+		return array_key_exists( $name, $this->fields );
+	}
+
+	/**
+	 * Gets if the id field is set.
+	 *
+	 * @since 0.1
+	 *
+	 * @return boolean
+	 */
+	public function hasIdField() {
+		return $this->hasField( 'id' )
+			&& !is_null( $this->getField( 'id' ) );
+	}
+
+	/**
+	 * Sets multiple fields.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array $fields The fields to set
+	 * @param boolean $override Override already set fields with the provided values?
+	 */
+	public function setFields( array $fields, $override = true ) {
+		foreach ( $fields as $name => $value ) {
+			if ( $override || !$this->hasField( $name ) ) {
+				$this->setField( $name, $value );
+			}
+		}
+	}
+
+	/**
+	 * Gets the fields => values to write to the table.
+	 *
+	 * @since 0.1
+	 *
+	 * @return array
+	 */
+	protected function getWriteValues() {
+		$values = array();
+
+		foreach ( $this->getFieldTypes() as $name => $type ) {
+			if ( array_key_exists( $name, $this->fields ) ) {
+				$value = $this->fields[$name];
+
+				switch ( $type ) {
+					case 'array':
+						$value = (array)$value;
+					case 'blob':
+						$value = serialize( $value );
+				}
+
+				$values[$this->getFieldPrefix() . $name] = $value;
+			}
+		}
+
+		return $values;
+	}
+
+	/**
+	 * Serializes the object to an associative array which
+	 * can then easily be converted into JSON or similar.
+	 *
+	 * @since 0.1
+	 *
+	 * @param null|array $fields
+	 * @param boolean $incNullId
+	 *
+	 * @return array
+	 */
+	public function toArray( $fields = null, $incNullId = false ) {
+		$data = array();
+		$setFields = array();
+
+		if ( !is_array( $fields ) ) {
+			$setFields = $this->getSetFieldNames();
+		} else {
+			foreach ( $fields as $field ) {
+				if ( $this->hasField( $field ) ) {
+					$setFields[] = $field;
+				}
+			}
+		}
+
+		foreach ( $setFields as $field ) {
+			if ( $incNullId || $field != 'id' || $this->hasIdField() ) {
+				$data[$field] = $this->getField( $field );
+			}
+		}
+
+		return $data;
+	}
+
+	/**
+	 * Load the default values, via getDefaults.
+	 *
+	 *  @since 0.1
+	 *
+	 * @param boolean $override
+	 */
+	public function loadDefaults( $override = true ) {
+		$this->setFields( $this->getDefaults(), $override );
+	}
+
+	/**
+	 * Writes the answer to the database, either updating it
+	 * when it already exists, or inserting it when it doesn't.
+	 *
+	 * @since 0.1
+	 *
+	 * @return boolean Success indicator
+	 */
+	public function save() {
+		if ( $this->hasIdField() ) {
+			return $this->saveExisting();
+		} else {
+			return $this->insert();
+		}
+	}
+
+	/**
+	 * Updates the object in the database.
+	 *
+	 * @since 0.1
+	 *
+	 * @return boolean Success indicator
+	 */
+	protected function saveExisting() {
+		$dbw = wfGetDB( DB_MASTER );
+
+		$success = $dbw->update(
+			$this->getDBTable(),
+			$this->getWriteValues(),
+			array( $this->getFieldPrefix() . 'id' => $this->getId() ),
+			__METHOD__
+		);
+
+		return $success;
+	}
+
+	/**
+	 * Inserts the object into the database.
+	 *
+	 * @since 0.1
+	 *
+	 * @return boolean Success indicator
+	 */
+	protected function insert() {
+		$dbw = wfGetDB( DB_MASTER );
+
+		$result = $dbw->insert(
+			$this->getDBTable(),
+			$this->getWriteValues(),
+			__METHOD__,
+			array( 'IGNORE' )
+		);
+
+		if ( $result ) {
+			$this->setField( 'id', $dbw->insertId() );
+		}
+
+		return $result;
+	}
+
+	/**
+	 * Removes the object from the database.
+	 *
+	 * @since 0.1
+	 *
+	 * @return boolean Success indicator
+	 */
+	public function remove() {
+		$this->beforeRemove();
+		
+		$success = static::delete( array( 'id' => $this->getId() ) );
+
+		if ( $success ) {
+			$this->onRemoved();
+		}
+
+		return $success;
+	}
+	
+	/**
+	 * Gets called before an object is removed from the database.
+	 * 
+	 * @since 0.1
+	 */
+	protected function beforeRemove() {
+		$this->loadFields( $this->getBeforeRemoveFields(), false, true );
+	}
+
+	/**
+	 * Before removal of an object happens, @see beforeRemove gets called.
+	 * This method loads the fields of which the names have been returned by this one (or all fields if null is returned).
+	 * This allows for loading info needed after removal to get rid of linked data and the like.
+	 * 
+	 * @since 0.1
+	 * 
+	 * @return array|null
+	 */
+	protected function getBeforeRemoveFields() {
+		return array();
+	}
+	
+	/**
+	 * Gets called after successfull removal.
+	 * Can be overriden to get rid of linked data.
+	 * 
+	 * @since 0.1
+	 */
+	protected function onRemoved() {
+		$this->setField( 'id', null );
+	}
+
+	/**
+	 * Return the names and values of the fields.
+	 *
+	 * @since 0.1
+	 *
+	 * @return array
+	 */
+	public function getFields() {
+		return $this->fields;
+	}
+
+	/**
+	 * Return the names of the fields.
+	 *
+	 * @since 0.1
+	 *
+	 * @return array
+	 */
+	public function getSetFieldNames() {
+		return array_keys( $this->fields );
+	}
+
+	/**
+	 * Sets the value of a field.
+	 * Strings can be provided for other types,
+	 * so this method can be called from unserialization handlers.
+	 *
+	 * @since 0.1
+	 *
+	 * @param string $name
+	 * @param mixed $value
+	 *
+	 * @throws MWException
+	 */
+	public function setField( $name, $value ) {
+		$fields = $this->getFieldTypes();
+
+		if ( array_key_exists( $name, $fields ) ) {
+			switch ( $fields[$name] ) {
+				case 'int':
+					$value = (int)$value;
+					break;
+				case 'float':
+					$value = (float)$value;
+					break;
+				case 'bool':
+					if ( is_string( $value ) ) {
+						$value = $value !== '0';
+					} elseif ( is_int( $value ) ) {
+						$value = $value !== 0;
+					}
+					break;
+				case 'array':
+					if ( is_string( $value ) ) {
+						$value = unserialize( $value );
+					}
+					
+					if ( !is_array( $value ) ) {
+						$value = array();
+					}
+					break;
+				case 'blob':
+					if ( is_string( $value ) ) {
+						$value = unserialize( $value );
+					}
+					break;
+				case 'id':
+					if ( is_string( $value ) ) {
+						$value = (int)$value;
+					}
+					break;
+			}
+
+			$this->fields[$name] = $value;
+		} else {
+			throw new MWException( 'Attempted to set unknown field ' . $name );
+		}
+	}
+
+	/**
+	 * Get a new instance of the class from an array.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array $data
+	 * @param boolean $loadDefaults
+	 *
+	 * @return DBDataObject
+	 */
+	public static function newFromArray( array $data, $loadDefaults = false ) {
+		return new static( $data, $loadDefaults );
+	}
+
+	/**
+	 * Get the database type used for read operations.
+	 *
+	 * @since 0.2
+	 * @return integer DB_ enum
+	 */
+	public static function getReadDb() {
+		return self::$readDb;
+	}
+
+	/**
+	 * Set the database type to use for read operations.
+	 *
+	 * @param integer $db
+	 *
+	 * @since 0.2
+	 */
+	public static function setReadDb( $db ) {
+		self::$readDb = $db;
+	}
+
+	/**
+	 * Gets if the object can take a certain field.
+	 *
+	 * @since 0.1
+	 *
+	 * @param string $name
+	 *
+	 * @return boolean
+	 */
+	public static function canHasField( $name ) {
+		return array_key_exists( $name, static::getFieldTypes() );
+	}
+
+	/**
+	 * Takes in a field or array of fields and returns an
+	 * array with their prefixed versions, ready for db usage.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array|string $fields
+	 *
+	 * @return array
+	 */
+	public static function getPrefixedFields( array $fields ) {
+		foreach ( $fields as &$field ) {
+			$field = static::getPrefixedField( $field );
+		}
+
+		return $fields;
+	}
+
+	/**
+	 * Takes in a field and returns an it's prefixed version, ready for db usage.
+	 * If the field needs to be prefixed for another table, provide an array in the form
+	 * array( 'tablename', 'fieldname' )
+	 * Where table name is registered in $wgDBDataObjects.
+	 *
+	 * @since 0.1
+	 *
+	 * @param string|array $field
+	 *
+	 * @return string
+	 * @throws MWException
+	 */
+	public static function getPrefixedField( $field ) {
+		static $prefixes = false;
+
+		if ( $prefixes === false ) {
+			foreach ( $GLOBALS['wgDBDataObjects'] as $classInfo ) {
+				$prefixes[$classInfo['table']] = $classInfo['prefix'];
+			}
+		}
+
+		if ( is_array( $field ) && count( $field ) > 1 ) {
+			if ( array_key_exists( $field[0], $prefixes ) ) {
+				$prefix = $prefixes[$field[0]];
+				$field = $field[1];
+			}
+			else {
+				throw new MWException( 'Tried to prefix field with unknown table "' . $field[0] . '"' );
+			}
+		}
+		else {
+			$prefix = static::getFieldPrefix();
+		}
+
+		return $prefix . $field;
+	}
+
+	/**
+	 * Takes in an associative array with field names as keys and
+	 * their values as value. The field names are prefixed with the
+	 * db field prefix.
+	 *
+	 * Field names can also be provided as an array with as first element a table name, such as
+	 * $conditions = array(
+	 *	 array( array( 'tablename', 'fieldname' ), $value ),
+	 * );
+	 *
+	 * @since 0.1
+	 *
+	 * @param array $values
+	 *
+	 * @return array
+	 */
+	public static function getPrefixedValues( array $values ) {
+		$prefixedValues = array();
+
+		foreach ( $values as $field => $value ) {
+			if ( is_integer( $field ) ) {
+				if ( is_array( $value ) ) {
+					$field = $value[0];
+					$value = $value[1];
+				}
+				else {
+					$value = explode( ' ', $value, 2 );
+					$value[0] = static::getPrefixedField( $value[0] );
+					$prefixedValues[] = implode( ' ', $value );
+					continue;
+				}
+			}
+
+			$prefixedValues[static::getPrefixedField( $field )] = $value;
+		}
+
+		return $prefixedValues;
+	}
+
+	/**
+	 * Get an array with fields from a database result,
+	 * that can be fed directly to the constructor or
+	 * to setFields.
+	 *
+	 * @since 0.1
+	 *
+	 * @param object $result
+	 *
+	 * @return array
+	 */
+	public static function getFieldsFromDBResult( $result ) {
+		$result = (array)$result;
+		return array_combine(
+			static::unprefixFieldNames( array_keys( $result ) ),
+			array_values( $result )
+		);
+	}
+
+	/**
+	 * Takes a field name with prefix and returns the unprefixed equivalent.
+	 *
+	 * @since 0.1
+	 *
+	 * @param string $fieldName
+	 *
+	 * @return string
+	 */
+	public static function unprefixFieldName( $fieldName ) {
+		return substr( $fieldName, strlen( static::getFieldPrefix() ) );
+	}
+
+	/**
+	 * Takes an array of field names with prefix and returns the unprefixed equivalent.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array $fieldNames
+	 *
+	 * @return array
+	 */
+	public static function unprefixFieldNames( array $fieldNames ) {
+		return array_map( 'static::unprefixFieldName', $fieldNames );
+	}
+
+	/**
+	 * Get a new instance of the class from a database result.
+	 *
+	 * @since 0.1
+	 *
+	 * @param stdClass $result
+	 *
+	 * @return DBDataObject
+	 */
+	public static function newFromDBResult( stdClass $result ) {
+		return static::newFromArray( static::getFieldsFromDBResult( $result ) );
+	}
+
+	/**
+	 * Removes the object from the database.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array $conditions
+	 *
+	 * @return boolean Success indicator
+	 */
+	public static function delete( array $conditions ) {
+		return wfGetDB( DB_MASTER )->delete(
+			static::getDBTable(),
+			static::getPrefixedValues( $conditions )
+		);
+	}
+
+	/**
+	 * Add an amount (can be negative) to the specified field (needs to be numeric).
+	 *
+	 * @since 0.1
+	 *
+	 * @param string $field
+	 * @param integer $amount
+	 *
+	 * @return boolean Success indicator
+	 */
+	public static function addToField( $field, $amount ) {
+		if ( $amount == 0 ) {
+			return true;
+		}
+
+		if ( !static::hasIdField() ) {
+			return false;
+		}
+
+		$absoluteAmount = abs( $amount );
+		$isNegative = $amount < 0;
+
+		$dbw = wfGetDB( DB_MASTER );
+
+		$fullField = static::getPrefixedField( $field );
+
+		$success = $dbw->update(
+			static::getDBTable(),
+			array( "$fullField=$fullField" . ( $isNegative ? '-' : '+' ) . $absoluteAmount ),
+			array( static::getPrefixedField( 'id' ) => static::getId() ),
+			__METHOD__
+		);
+
+		if ( $success && static::hasField( $field ) ) {
+			static::setField( $field, static::getField( $field ) + $amount );
+		}
+
+		return $success;
+	}
+
+	/**
+	 * Selects the the specified fields of the records matching the provided
+	 * conditions and returns them as DBDataObject. Field names get prefixed.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array|string|null $fields
+	 * @param array $conditions
+	 * @param array $options
+	 * @param array $joinConds
+	 *
+	 * @return array of self
+	 */
+	public static function select( $fields = null, array $conditions = array(), array $options = array(), array $joinConds = array() ) {
+		$result = static::selectFields( $fields, $conditions, $options, $joinConds, false );
+
+		$objects = array();
+
+		foreach ( $result as $record ) {
+			$objects[] = static::newFromArray( $record );
+		}
+
+		return $objects;
+	}
+
+	/**
+	 * Selects the the specified fields of the records matching the provided
+	 * conditions and returns them as associative arrays.
+	 * Provided field names get prefixed.
+	 * Returned field names will not have a prefix.
+	 *
+	 * When $collapse is true:
+	 * If one field is selected, each item in the result array will be this field.
+	 * If two fields are selected, each item in the result array will have as key
+	 * the first field and as value the second field.
+	 * If more then two fields are selected, each item will be an associative array.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array|string|null $fields
+	 * @param array $conditions
+	 * @param array $options
+	 * @param array $joinConds
+	 * @param boolean $collapse Set to false to always return each result row as associative array.
+	 *
+	 * @return array of array
+	 */
+	public static function selectFields( $fields = null, array $conditions = array(), array $options = array(), array $joinConds = array(), $collapse = true ) {
+		if ( is_null( $fields ) ) {
+			$fields = array_keys( static::getFieldTypes() );
+		}
+		else {
+			$fields = (array)$fields;
+		}
+
+		$tables = array( static::getDBTable() );
+		$joinConds = static::getProcessedJoinConds( $joinConds, $tables );
+
+		$result = static::rawSelect(
+			static::getPrefixedFields( $fields ),
+			static::getPrefixedValues( $conditions ),
+			$options,
+			$joinConds,
+			$tables
+		);
+
+		$objects = array();
+
+		foreach ( $result as $record ) {
+			$objects[] = static::getFieldsFromDBResult( $record );
+		}
+
+		if ( $collapse ) {
+			if ( count( $fields ) === 1 ) {
+				$objects = array_map( function( $object ) { return array_shift( $object ); } , $objects );
+			}
+			elseif ( count( $fields ) === 2 ) {
+				$o = array();
+
+				foreach ( $objects as $object ) {
+					$o[array_shift( $object )] = array_shift( $object );
+				}
+
+				$objects = $o;
+			}
+		}
+
+		return $objects;
+	}
+
+	/**
+	 * Process the join conditions. This includes prefixing table and field names,
+	 * and adding of needed tables.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array $joinConds Join conditions without prefixes and fields in array rather then string with equals sign.
+	 * @param array $tables List of tables to which the extra needed ones get added.
+	 *
+	 * @return array Join conditions ready to be fed to MediaWikis native select function.
+	 */
+	protected static function getProcessedJoinConds( array $joinConds, array &$tables ) {
+		$conds = array();
+
+		foreach ( $joinConds as $table => $joinCond ) {
+			if ( !in_array( $table, $tables ) ) {
+				$tables[] = $table;
+			}
+
+			$cond = array( $joinCond[0], array() );
+
+			foreach ( $joinCond[1] as $joinCondPart ) {
+				$parts = array(
+					static::getPrefixedField( $joinCondPart[0] ),
+					static::getPrefixedField( $joinCondPart[1] ),
+				);
+
+				if ( !in_array( $joinCondPart[0][0], $tables ) ) {
+					$tables[] = $joinCondPart[0][0];
+				}
+
+				if ( !in_array( $joinCondPart[1][0], $tables ) ) {
+					$tables[] = $joinCondPart[1][0];
+				}
+
+				$cond[1][] = implode( '=', $parts );
+			}
+
+			$conds[$table] = $cond;
+		}
+
+		return $conds;
+	}
+
+	/**
+	 * Selects the the specified fields of the first matching record.
+	 * Field names get prefixed.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array|string|null $fields
+	 * @param array $conditions
+	 * @param array $options
+	 * @param array $joinConds
+	 *
+	 * @return EPBObject|false
+	 */
+	public static function selectRow( $fields = null, array $conditions = array(), array $options = array(), array $joinConds = array() ) {
+		$options['LIMIT'] = 1;
+
+		$objects = static::select( $fields, $conditions, $options, $joinConds );
+
+		return count( $objects ) > 0 ? $objects[0] : false;
+	}
+
+	/**
+	 * Selects the the specified fields of the first record matching the provided
+	 * conditions and returns it as an associative array, or false when nothing matches.
+	 * This method makes use of selectFields and expects the same parameters and
+	 * returns the same results (if there are any, if there are none, this method returns false).
+	 * @see DBDataObject::selectFields
+	 *
+	 * @since 0.1
+	 *
+	 * @param array|string|null $fields
+	 * @param array $conditions
+	 * @param array $options
+	 * @param array $joinConds
+	 * @param boolean $collapse Set to false to always return each result row as associative array.
+	 *
+	 * @return mixed|array|false
+	 */
+	public static function selectFieldsRow( $fields = null, array $conditions = array(), array $options = array(), array $joinConds = array(), $collapse = true ) {
+		$options['LIMIT'] = 1;
+
+		$objects = static::selectFields( $fields, $conditions, $options, $joinConds, $collapse );
+
+		return count( $objects ) > 0 ? $objects[0] : false;
+	}
+
+	/**
+	 * Returns if there is at least one record matching the provided conditions.
+	 * Condition field names get prefixed.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array $conditions
+	 *
+	 * @return boolean
+	 */
+	public static function has( array $conditions = array() ) {
+		return static::selectRow( array( 'id' ), $conditions ) !== false;
+	}
+
+	/**
+	 * Returns the amount of matching records.
+	 * Condition field names get prefixed.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array $conditions
+	 * @param array $options
+	 *
+	 * @return integer
+	 */
+	public static function count( array $conditions = array(), array $options = array() ) {
+		$res = static::rawSelect(
+			array( 'COUNT(*) AS rowcount' ),
+			static::getPrefixedValues( $conditions ),
+			$options
+		)->fetchObject();
+
+		return $res->rowcount;
+	}
+
+	/**
+	 * Selects the the specified fields of the records matching the provided
+	 * conditions. Field names do NOT get prefixed.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array $fields
+	 * @param array $conditions
+	 * @param array $options
+	 * @param array $joinConds
+	 * @param array $tables
+	 *
+	 * @return ResultWrapper
+	 */
+	public static function rawSelect( array $fields, array $conditions = array(), array $options = array(), array $joinConds = array(), array $tables = null ) {
+		if ( is_null( $tables ) ) {
+			$tables = static::getDBTable();
+		}
+
+		$dbr = wfGetDB( static::getReadDb() );
+
+		return $dbr->select(
+			$tables,
+			$fields,
+			count( $conditions ) == 0 ? '' : $conditions,
+			__METHOD__,
+			$options,
+			$joinConds
+		);
+	}
+
+	/**
+	 * Update the records matching the provided conditions by
+	 * setting the fields that are keys in the $values param to
+	 * their corresponding values.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array $values
+	 * @param array $conditions
+	 *
+	 * @return boolean Success indicator
+	 */
+	public static function update( array $values, array $conditions = array() ) {
+		$dbw = wfGetDB( DB_MASTER );
+
+		return $dbw->update(
+			static::getDBTable(),
+			static::getPrefixedValues( $values ),
+			static::getPrefixedValues( $conditions ),
+			__METHOD__
+		);
+	}
+
+	/**
+	 * Return the names of the fields.
+	 *
+	 * @since 0.1
+	 *
+	 * @return array
+	 */
+	public static function getFieldNames() {
+		return array_keys( static::getFieldTypes() );
+	}
+
+	/**
+	 * Returns an array with the fields and their descriptions.
+	 *
+	 * field name => field description
+	 *
+	 * @since 0.1
+	 *
+	 * @return array
+	 */
+	public static function getFieldDescriptions() {
+		return array();
+	}
+
+	/**
+	 * Get API parameters for the fields supported by this object.
+	 *
+	 * @since 0.1
+	 *
+	 * @param boolean $requireParams
+	 * @param boolean $setDefaults
+	 *
+	 * @return array
+	 */
+	public static function getAPIParams( $requireParams = false, $setDefaults = false ) {
+		$typeMap = array(
+			'id' => 'integer',
+			'int' => 'integer',
+			'float' => 'NULL',
+			'str' => 'string',
+			'bool' => 'integer',
+			'array' => 'string',
+			'blob' => 'string',
+		);
+
+		$params = array();
+		$defaults = static::getDefaults();
+
+		foreach ( static::getFieldTypes() as $field => $type ) {
+			if ( $field == 'id' ) {
+				continue;
+			}
+
+			$hasDefault = array_key_exists( $field, $defaults );
+
+			$params[$field] = array(
+				ApiBase::PARAM_TYPE => $typeMap[$type],
+				ApiBase::PARAM_REQUIRED => $requireParams && !$hasDefault
+			);
+
+			if ( $type == 'array' ) {
+				$params[$field][ApiBase::PARAM_ISMULTI] = true;
+			}
+
+			if ( $setDefaults && $hasDefault ) {
+				$default = is_array( $defaults[$field] ) ? implode( '|', $defaults[$field] ) : $defaults[$field];
+				$params[$field][ApiBase::PARAM_DFLT] = $default;
+			}
+		}
+
+		return $params;
+	}
+
+	/**
+	 * Computes and updates the values of the summary fields.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array|string|null $summaryFields
+	 */
+	public function loadSummaryFields( $summaryFields = null ) {
+
+	}
+
+	/**
+	 * Computes the values of the summary fields of the objects matching the provided conditions.
+	 *
+	 * @since 0.1
+	 *
+	 * @param array|string|null $summaryFields
+	 * @param array $conditions
+	 */
+	public static function updateSummaryFields( $summaryFields = null, array $conditions = array() ) {
+		self::setReadDb( DB_MASTER );
+
+		foreach ( self::select( null, $conditions ) as /* DBDataObject */ $item ) {
+			$item->loadSummaryFields( $summaryFields );
+			$item->setSummaryMode( true );
+			$item->saveExisting();
+		}
+
+		self::setReadDb( DB_SLAVE );
+	}
+
+	/**
+	 * Sets the value for the @see $updateSummaries field.
+	 *
+	 * @since 0.1
+	 *
+	 * @param boolean $update
+	 */
+	public function setUpdateSummaries( $update ) {
+		$this->updateSummaries = $update;
+	}
+
+	/**
+	 * Sets the value for the @see $inSummaryMode field.
+	 *
+	 * @since 0.1
+	 *
+	 * @param boolean $update
+	 */
+	public function setSummaryMode( $summaryMode ) {
+		$this->inSummaryMode = $summaryMode;
+	}
+
+	/**
+	 * Return if any fields got changed.
+	 *
+	 * @since 0.1
+	 *
+	 * @param DBDataObject $object
+	 * @param boolean $excludeSummaryFields When set to true, summary field changes are ignored.
+	 *
+	 * @return boolean
+	 */
+	protected function fieldsChanged( DBDataObject $object, $excludeSummaryFields = false ) {
+		foreach ( $this->fields as $name => $value ) {
+			$excluded = $excludeSummaryFields && in_array( $name, $this->getSummaryFields() );
+
+			if ( !$excluded && $object->getField( $name ) !== $value ) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+}
-- 
2.20.1