framework/db/DataReader.php
<?php
/**
* @link https://www.yiiframework.com/
* @copyright Copyright (c) 2008 Yii Software LLC
* @license https://www.yiiframework.com/license/
*/
namespace yii\db;
use yii\base\InvalidCallException;
/**
* DataReader represents a forward-only stream of rows from a query result set.
*
* To read the current row of data, call [[read()]]. The method [[readAll()]]
* returns all the rows in a single array. Rows of data can also be read by
* iterating through the reader. For example,
*
* ```php
* $command = $connection->createCommand('SELECT * FROM post');
* $reader = $command->query();
*
* while ($row = $reader->read()) {
* $rows[] = $row;
* }
*
* // equivalent to:
* foreach ($reader as $row) {
* $rows[] = $row;
* }
*
* // equivalent to:
* $rows = $reader->readAll();
* ```
*
* Note that since DataReader is a forward-only stream, you can only traverse it once.
* Doing it the second time will throw an exception.
*
* It is possible to use a specific mode of data fetching by setting
* [[fetchMode]]. See the [PHP manual](https://www.php.net/manual/en/function.PDOStatement-setFetchMode.php)
* for more details about possible fetch mode.
*
* @property-read int $columnCount The number of columns in the result set.
* @property-write int $fetchMode Fetch mode.
* @property-read bool $isClosed Whether the reader is closed or not.
* @property-read int $rowCount Number of rows contained in the result.
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @since 2.0
*/
class DataReader extends \yii\base\BaseObject implements \Iterator, \Countable
{
/**
* @var \PDOStatement the PDOStatement associated with the command
*/
private $_statement;
private $_closed = false;
private $_row;
private $_index = -1;
/**
* Constructor.
* @param Command $command the command generating the query result
* @param array $config name-value pairs that will be used to initialize the object properties
*/
public function __construct(Command $command, $config = [])
{
$this->_statement = $command->pdoStatement;
$this->_statement->setFetchMode(\PDO::FETCH_ASSOC);
parent::__construct($config);
}
/**
* Binds a column to a PHP variable.
* When rows of data are being fetched, the corresponding column value
* will be set in the variable. Note, the fetch mode must include PDO::FETCH_BOUND.
* @param int|string $column Number of the column (1-indexed) or name of the column
* in the result set. If using the column name, be aware that the name
* should match the case of the column, as returned by the driver.
* @param mixed $value Name of the PHP variable to which the column will be bound.
* @param int|null $dataType Data type of the parameter
* @see https://www.php.net/manual/en/function.PDOStatement-bindColumn.php
*/
public function bindColumn($column, &$value, $dataType = null)
{
if ($dataType === null) {
$this->_statement->bindColumn($column, $value);
} else {
$this->_statement->bindColumn($column, $value, $dataType);
}
}
/**
* Set the default fetch mode for this statement.
*
* @param int $mode fetch mode
* @see https://www.php.net/manual/en/function.PDOStatement-setFetchMode.php
*/
public function setFetchMode($mode)
{
$params = func_get_args();
call_user_func_array([$this->_statement, 'setFetchMode'], $params);
}
/**
* Advances the reader to the next row in a result set.
* @return array the current row, false if no more row available
*/
public function read()
{
return $this->_statement->fetch();
}
/**
* Returns a single column from the next row of a result set.
* @param int $columnIndex zero-based column index
* @return mixed the column of the current row, false if no more rows available
*/
public function readColumn($columnIndex)
{
return $this->_statement->fetchColumn($columnIndex);
}
/**
* Returns an object populated with the next row of data.
* @param string $className class name of the object to be created and populated
* @param array $fields Elements of this array are passed to the constructor
* @return mixed the populated object, false if no more row of data available
*/
public function readObject($className, $fields)
{
return $this->_statement->fetchObject($className, $fields);
}
/**
* Reads the whole result set into an array.
* @return array the result set (each array element represents a row of data).
* An empty array will be returned if the result contains no row.
*/
public function readAll()
{
return $this->_statement->fetchAll();
}
/**
* Advances the reader to the next result when reading the results of a batch of statements.
* This method is only useful when there are multiple result sets
* returned by the query. Not all DBMS support this feature.
* @return bool Returns true on success or false on failure.
*/
public function nextResult()
{
if (($result = $this->_statement->nextRowset()) !== false) {
$this->_index = -1;
}
return $result;
}
/**
* Closes the reader.
* This frees up the resources allocated for executing this SQL statement.
* Read attempts after this method call are unpredictable.
*/
public function close()
{
$this->_statement->closeCursor();
$this->_closed = true;
}
/**
* whether the reader is closed or not.
* @return bool whether the reader is closed or not.
*/
public function getIsClosed()
{
return $this->_closed;
}
/**
* Returns the number of rows in the result set.
* Note, most DBMS may not give a meaningful count.
* In this case, use "SELECT COUNT(*) FROM tableName" to obtain the number of rows.
* @return int number of rows contained in the result.
*/
public function getRowCount()
{
return $this->_statement->rowCount();
}
/**
* Returns the number of rows in the result set.
* This method is required by the Countable interface.
* Note, most DBMS may not give a meaningful count.
* In this case, use "SELECT COUNT(*) FROM tableName" to obtain the number of rows.
* @return int number of rows contained in the result.
*/
#[\ReturnTypeWillChange]
public function count()
{
return $this->getRowCount();
}
/**
* Returns the number of columns in the result set.
* Note, even there's no row in the reader, this still gives correct column number.
* @return int the number of columns in the result set.
*/
public function getColumnCount()
{
return $this->_statement->columnCount();
}
/**
* Resets the iterator to the initial state.
* This method is required by the interface [[\Iterator]].
* @throws InvalidCallException if this method is invoked twice
*/
#[\ReturnTypeWillChange]
public function rewind()
{
if ($this->_index < 0) {
$this->_row = $this->_statement->fetch();
$this->_index = 0;
} else {
throw new InvalidCallException('DataReader cannot rewind. It is a forward-only reader.');
}
}
/**
* Returns the index of the current row.
* This method is required by the interface [[\Iterator]].
* @return int the index of the current row.
*/
#[\ReturnTypeWillChange]
public function key()
{
return $this->_index;
}
/**
* Returns the current row.
* This method is required by the interface [[\Iterator]].
* @return mixed the current row.
*/
#[\ReturnTypeWillChange]
public function current()
{
return $this->_row;
}
/**
* Moves the internal pointer to the next row.
* This method is required by the interface [[\Iterator]].
*/
#[\ReturnTypeWillChange]
public function next()
{
$this->_row = $this->_statement->fetch();
$this->_index++;
}
/**
* Returns whether there is a row of data at current position.
* This method is required by the interface [[\Iterator]].
* @return bool whether there is a row of data at current position.
*/
#[\ReturnTypeWillChange]
public function valid()
{
return $this->_row !== false;
}
}