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[mediawiki.git] / includes / db / ORMTable.php

<?php

/**
 * Abstract base class for representing a single database table.
 *
 * @since 1.20
 *
 * @file ORMTable.php
 *
 * @licence GNU GPL v2 or later
 * @author Jeroen De Dauw < jeroendedauw@gmail.com >
 */
abstract class ORMTable {

        /**
         * Returns the name of the database table objects of this type are stored in.
         *
         * @since 1.20
         *
         * @return string
         */
        public abstract function getName();

        /**
         * Returns the name of a ORMRow deriving class that
         * represents single rows in this table.
         *
         * @since 1.20
         *
         * @return string
         */
        public abstract function getRowClass();

        /**
         * Gets the db field prefix.
         *
         * @since 1.20
         *
         * @return string
         */
        protected abstract function getFieldPrefix();

        /**
         * 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 1.20
         *
         * @return array
         */
        public abstract function getFields();

        /**
         * Cache for instances, used by the singleton method.
         *
         * @since 1.20
         * @var array of DBTable
         */
        protected static $instanceCache = array();

        /**
         * The database connection to use for read operations.
         * Can be changed via @see setReadDb.
         *
         * @since 1.20
         * @var integer DB_ enum
         */
        protected $readDb = DB_SLAVE;

        /**
         * Returns a list of default field values.
         * field name => field value
         *
         * @since 1.20
         *
         * @return array
         */
        public 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 1.20
         *
         * @return array
         */
        public function getSummaryFields() {
                return array();
        }

        /**
         * Selects the the specified fields of the records matching the provided
         * conditions and returns them as DBDataObject. Field names get prefixed.
         *
         * @since 1.20
         *
         * @param array|string|null $fields
         * @param array $conditions
         * @param array $options
         * @param string|null $functionName
         *
         * @return ORMResult
         */
        public function select( $fields = null, array $conditions = array(),
                                                        array $options = array(), $functionName  = null ) {
                return new ORMResult( $this, $this->rawSelect( $fields, $conditions, $options, $functionName ) );
        }

        /**
         * Selects the the specified fields of the records matching the provided
         * conditions and returns them as DBDataObject. Field names get prefixed.
         *
         * @since 1.20
         *
         * @param array|string|null $fields
         * @param array $conditions
         * @param array $options
         * @param string|null $functionName
         *
         * @return array of self
         */
        public function selectObjects( $fields = null, array $conditions = array(),
                                                                   array $options = array(), $functionName  = null ) {
                $result = $this->selectFields( $fields, $conditions, $options, false, $functionName );

                $objects = array();

                foreach ( $result as $record ) {
                        $objects[] = $this->newFromArray( $record );
                }

                return $objects;
        }

        /**
         * Do the actual select.
         *
         * @since 1.20
         *
         * @param null|string|array $fields
         * @param array $conditions
         * @param array $options
         * @param null|string $functionName
         *
         * @return ResultWrapper
         */
        public function rawSelect( $fields = null, array $conditions = array(),
                                                           array $options = array(), $functionName  = null ) {
                if ( is_null( $fields ) ) {
                        $fields = array_keys( $this->getFields() );
                }
                else {
                        $fields = (array)$fields;
                }

                return wfGetDB( $this->getReadDb() )->select(
                        $this->getName(),
                        $this->getPrefixedFields( $fields ),
                        $this->getPrefixedValues( $conditions ),
                        is_null( $functionName ) ? __METHOD__ : $functionName,
                        $options
                );
        }

        /**
         * 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 1.20
         *
         * @param array|string|null $fields
         * @param array $conditions
         * @param array $options
         * @param boolean $collapse Set to false to always return each result row as associative array.
         * @param string|null $functionName
         *
         * @return array of array
         */
        public function selectFields( $fields = null, array $conditions = array(),
                                                                  array $options = array(), $collapse = true, $functionName  = null ) {
                $objects = array();

                $result = $this->rawSelect( $fields, $conditions, $options, $functionName );

                foreach ( $result as $record ) {
                        $objects[] = $this->getFieldsFromDBResult( $record );
                }

                if ( $collapse ) {
                        if ( count( $fields ) === 1 ) {
                                $objects = array_map( 'array_shift', $objects );
                        }
                        elseif ( count( $fields ) === 2 ) {
                                $o = array();

                                foreach ( $objects as $object ) {
                                        $o[array_shift( $object )] = array_shift( $object );
                                }

                                $objects = $o;
                        }
                }

                return $objects;
        }

        /**
         * Selects the the specified fields of the first matching record.
         * Field names get prefixed.
         *
         * @since 1.20
         *
         * @param array|string|null $fields
         * @param array $conditions
         * @param array $options
         * @param string|null $functionName
         *
         * @return DBObject|bool False on failure
         */
        public function selectRow( $fields = null, array $conditions = array(),
                                                           array $options = array(), $functionName = null ) {
                $options['LIMIT'] = 1;

                $objects = $this->select( $fields, $conditions, $options, $functionName );

                return $objects->isEmpty() ? false : $objects->current();
        }

        /**
         * Selects the the specified fields of the records matching the provided
         * conditions. Field names do NOT get prefixed.
         *
         * @since 1.20
         *
         * @param array $fields
         * @param array $conditions
         * @param array $options
         * @param string|null $functionName
         *
         * @return ResultWrapper
         */
        public function rawSelectRow( array $fields, array $conditions = array(),
                                                                  array $options = array(), $functionName = null ) {
                $dbr = wfGetDB( $this->getReadDb() );

                return $dbr->selectRow(
                        $this->getName(),
                        $fields,
                        $conditions,
                        is_null( $functionName ) ? __METHOD__ : $functionName,
                        $options
                );
        }

        /**
         * 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 ORMTable::selectFields
         *
         * @since 1.20
         *
         * @param array|string|null $fields
         * @param array $conditions
         * @param array $options
         * @param boolean $collapse Set to false to always return each result row as associative array.
         * @param string|null $functionName
         *
         * @return mixed|array|bool False on failure
         */
        public function selectFieldsRow( $fields = null, array $conditions = array(),
                                                                         array $options = array(), $collapse = true, $functionName = null ) {
                $options['LIMIT'] = 1;

                $objects = $this->selectFields( $fields, $conditions, $options, $collapse, $functionName );

                return empty( $objects ) ? false : $objects[0];
        }

        /**
         * Returns if there is at least one record matching the provided conditions.
         * Condition field names get prefixed.
         *
         * @since 1.20
         *
         * @param array $conditions
         *
         * @return boolean
         */
        public function has( array $conditions = array() ) {
                return $this->selectRow( array( 'id' ), $conditions ) !== false;
        }

        /**
         * Returns the amount of matching records.
         * Condition field names get prefixed.
         *
         * Note that this can be expensive on large tables.
         * In such cases you might want to use DatabaseBase::estimateRowCount instead.
         *
         * @since 1.20
         *
         * @param array $conditions
         * @param array $options
         *
         * @return integer
         */
        public function count( array $conditions = array(), array $options = array() ) {
                $res = $this->rawSelectRow(
                        array( 'COUNT(*) AS rowcount' ),
                        $this->getPrefixedValues( $conditions ),
                        $options
                );

                return $res->rowcount;
        }

        /**
         * Removes the object from the database.
         *
         * @since 1.20
         *
         * @param array $conditions
         * @param string|null $functionName
         *
         * @return boolean Success indicator
         */
        public function delete( array $conditions, $functionName = null ) {
                return wfGetDB( DB_MASTER )->delete(
                        $this->getName(),
                        $this->getPrefixedValues( $conditions ),
                        $functionName
                );
        }
        
        /**
         * Get API parameters for the fields supported by this object.
         *
         * @since 1.20
         *
         * @param boolean $requireParams
         * @param boolean $setDefaults
         *
         * @return array
         */
        public 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 = $this->getDefaults();

                foreach ( $this->getFields() 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;
        }

        /**
         * Returns an array with the fields and their descriptions.
         *
         * field name => field description
         *
         * @since 1.20
         *
         * @return array
         */
        public function getFieldDescriptions() {
                return array();
        }

        /**
         * Get the database type used for read operations.
         *
         * @since 1.20
         *
         * @return integer DB_ enum
         */
        public function getReadDb() {
                return $this->readDb;
        }

        /**
         * Set the database type to use for read operations.
         *
         * @param integer $db
         *
         * @since 1.20
         */
        public function setReadDb( $db ) {
                $this->readDb = $db;
        }

        /**
         * Update the records matching the provided conditions by
         * setting the fields that are keys in the $values param to
         * their corresponding values.
         *
         * @since 1.20
         *
         * @param array $values
         * @param array $conditions
         *
         * @return boolean Success indicator
         */
        public function update( array $values, array $conditions = array() ) {
                $dbw = wfGetDB( DB_MASTER );

                return $dbw->update(
                        $this->getName(),
                        $this->getPrefixedValues( $values ),
                        $this->getPrefixedValues( $conditions ),
                        __METHOD__
                );
        }

        /**
         * Computes the values of the summary fields of the objects matching the provided conditions.
         *
         * @since 1.20
         *
         * @param array|string|null $summaryFields
         * @param array $conditions
         */
        public function updateSummaryFields( $summaryFields = null, array $conditions = array() ) {
                $this->setReadDb( DB_MASTER );

                foreach ( $this->select( null, $conditions ) as /* ORMRow */ $item ) {
                        $item->loadSummaryFields( $summaryFields );
                        $item->setSummaryMode( true );
                        $item->save();
                }

                $this->setReadDb( DB_SLAVE );
        }

        /**
         * 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 1.20
         *
         * @param array $values
         *
         * @return array
         */
        public 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] = $this->getPrefixedField( $value[0] );
                                        $prefixedValues[] = implode( ' ', $value );
                                        continue;
                                }
                        }

                        $prefixedValues[$this->getPrefixedField( $field )] = $value;
                }

                return $prefixedValues;
        }

        /**
         * Takes in a field or array of fields and returns an
         * array with their prefixed versions, ready for db usage.
         *
         * @since 1.20
         *
         * @param array|string $fields
         *
         * @return array
         */
        public function getPrefixedFields( array $fields ) {
                foreach ( $fields as &$field ) {
                        $field = $this->getPrefixedField( $field );
                }

                return $fields;
        }

        /**
         * Takes in a field and returns an it's prefixed version, ready for db usage.
         *
         * @since 1.20
         *
         * @param string|array $field
         *
         * @return string
         */
        public function getPrefixedField( $field ) {
                return $this->getFieldPrefix() . $field;
        }

        /**
         * Takes an array of field names with prefix and returns the unprefixed equivalent.
         *
         * @since 1.20
         *
         * @param array $fieldNames
         *
         * @return array
         */
        public function unprefixFieldNames( array $fieldNames ) {
                return array_map( array( $this, 'unprefixFieldName' ), $fieldNames );
        }

        /**
         * Takes a field name with prefix and returns the unprefixed equivalent.
         *
         * @since 1.20
         *
         * @param string $fieldName
         *
         * @return string
         */
        public function unprefixFieldName( $fieldName ) {
                return substr( $fieldName, strlen( $this->getFieldPrefix() ) );
        }

        /**
         * Get an instance of this class.
         *
         * @since 1.20
         *
         * @return ORMTable
         */
        public static function singleton() {
                $class = function_exists( 'get_called_class' ) ? get_called_class() : self::get_called_class();

                if ( !array_key_exists( $class, self::$instanceCache ) ) {
                        self::$instanceCache[$class] = new $class;
                }

                return self::$instanceCache[$class];
        }

        /**
         * Compatibility fallback function so the singleton method works on PHP < 5.3.
         * Code borrowed from http://www.php.net/manual/en/function.get-called-class.php#107445
         *
         * @since 1.20
         *
         * @return string
         */
        protected static function get_called_class() {
                $bt = debug_backtrace();
                $l = count($bt) - 1;
                $matches = array();
                while(empty($matches) && $l > -1){
                        $lines = file($bt[$l]['file']);
                        $callerLine = $lines[$bt[$l]['line']-1];
                        preg_match('/([a-zA-Z0-9\_]+)::'.$bt[$l--]['function'].'/',
                                $callerLine,
                                $matches);
                }
                if (!isset($matches[1])) $matches[1]=NULL; //for notices
                if ($matches[1] == 'self') {
                        $line = $bt[$l]['line']-1;
                        while ($line > 0 && strpos($lines[$line], 'class') === false) {
                                $line--;
                        }
                        preg_match('/class[\s]+(.+?)[\s]+/si', $lines[$line], $matches);
                }
                return $matches[1];
        }

        /**
         * Get an array with fields from a database result,
         * that can be fed directly to the constructor or
         * to setFields.
         *
         * @since 1.20
         *
         * @param stdClass $result
         *
         * @return array
         */
        public function getFieldsFromDBResult( stdClass $result ) {
                $result = (array)$result;
                return array_combine(
                        $this->unprefixFieldNames( array_keys( $result ) ),
                        array_values( $result )
                );
        }

        /**
         * Get a new instance of the class from a database result.
         *
         * @since 1.20
         *
         * @param stdClass $result
         *
         * @return ORMRow
         */
        public function newFromDBResult( stdClass $result ) {
                return $this->newFromArray( $this->getFieldsFromDBResult( $result ) );
        }

        /**
         * Get a new instance of the class from an array.
         *
         * @since 1.20
         *
         * @param array $data
         * @param boolean $loadDefaults
         *
         * @return ORMRow
         */
        public function newFromArray( array $data, $loadDefaults = false ) {
                $class = $this->getRowClass();
                return new $class( $this, $data, $loadDefaults );
        }

        /**
         * Return the names of the fields.
         *
         * @since 1.20
         *
         * @return array
         */
        public function getFieldNames() {
                return array_keys( $this->getFields() );
        }

        /**
         * Gets if the object can take a certain field.
         *
         * @since 1.20
         *
         * @param string $name
         *
         * @return boolean
         */
        public function canHaveField( $name ) {
                return array_key_exists( $name, $this->getFields() );
        }

}