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<?php
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/**
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* @link http://www.yiiframework.com/
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* @copyright Copyright (c) 2008 Yii Software LLC
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* @license http://www.yiiframework.com/license/
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*/
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namespace yii\db;
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use yii\base\Object;
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/**
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* BatchQueryResult represents a batch query from which you can retrieve data in batches.
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*
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* You usually do not instantiate BatchQueryResult directly. Instead, you obtain it by
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* calling [[Query::batch()]] or [[Query::each()]]. Because BatchQueryResult implements the [[\Iterator]] interface,
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* you can iterate it to obtain a batch of data in each iteration. For example,
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*
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* ```php
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* $query = (new Query)->from('user');
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* foreach ($query->batch() as $i => $users) {
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* // $users represents the rows in the $i-th batch
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* }
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* foreach ($query->each() as $user) {
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* }
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* ```
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*
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* @author Qiang Xue <qiang.xue@gmail.com>
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* @since 2.0
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*/
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class BatchQueryResult extends Object implements \Iterator
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{
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/**
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* @var Connection the DB connection to be used when performing batch query.
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* If null, the "db" application component will be used.
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*/
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public $db;
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/**
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* @var Query the query object associated with this batch query.
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* Do not modify this property directly unless after [[reset()]] is called explicitly.
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*/
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public $query;
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/**
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* @var integer the number of rows to be returned in each batch.
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*/
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public $batchSize = 100;
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/**
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* @var boolean whether to return a single row during each iteration.
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* If false, a whole batch of rows will be returned in each iteration.
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*/
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public $each = false;
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/**
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* @var DataReader the data reader associated with this batch query.
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*/
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private $_dataReader;
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/**
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* @var array the data retrieved in the current batch
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*/
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private $_batch;
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/**
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* @var mixed the value for the current iteration
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*/
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private $_value;
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/**
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* @var string|integer the key for the current iteration
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*/
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private $_key;
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/**
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* Destructor.
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*/
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public function __destruct()
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{
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// make sure cursor is closed
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$this->reset();
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}
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/**
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* Resets the batch query.
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* This method will clean up the existing batch query so that a new batch query can be performed.
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*/
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public function reset()
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{
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if ($this->_dataReader !== null) {
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$this->_dataReader->close();
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}
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$this->_dataReader = null;
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$this->_batch = null;
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$this->_value = null;
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$this->_key = null;
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}
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/**
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* Resets the iterator to the initial state.
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* This method is required by the interface [[\Iterator]].
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*/
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public function rewind()
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{
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$this->reset();
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$this->next();
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}
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/**
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* Moves the internal pointer to the next dataset.
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* This method is required by the interface [[\Iterator]].
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*/
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public function next()
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{
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if ($this->_batch === null || !$this->each || $this->each && next($this->_batch) === false) {
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$this->_batch = $this->fetchData();
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reset($this->_batch);
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}
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if ($this->each) {
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$this->_value = current($this->_batch);
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if ($this->query->indexBy !== null) {
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$this->_key = key($this->_batch);
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} elseif (key($this->_batch) !== null) {
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$this->_key++;
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} else {
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$this->_key = null;
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}
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} else {
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$this->_value = $this->_batch;
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$this->_key = $this->_key === null ? 0 : $this->_key + 1;
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}
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}
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/**
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* Fetches the next batch of data.
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* @return array the data fetched
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*/
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protected function fetchData()
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{
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if ($this->_dataReader === null) {
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$this->_dataReader = $this->query->createCommand($this->db)->query();
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}
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$rows = [];
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$count = 0;
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while ($count++ < $this->batchSize && ($row = $this->_dataReader->read())) {
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$rows[] = $row;
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}
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return $this->query->populate($rows);
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}
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/**
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* Returns the index of the current dataset.
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* This method is required by the interface [[\Iterator]].
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* @return integer the index of the current row.
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*/
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public function key()
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{
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return $this->_key;
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}
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/**
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* Returns the current dataset.
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* This method is required by the interface [[\Iterator]].
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* @return mixed the current dataset.
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*/
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public function current()
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{
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return $this->_value;
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}
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/**
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* Returns whether there is a valid dataset at the current position.
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* This method is required by the interface [[\Iterator]].
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* @return boolean whether there is a valid dataset at the current position.
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*/
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public function valid()
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{
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return !empty($this->_batch);
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}
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}
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