* @link http://www.yiiframework.com/
* @copyright Copyright © 2008-2011 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
/**
* CDbDataReader represents a forward-only stream of rows from a query result set.
*
* To read the current row of data, call {@link read}. The method {@link readAll}
* returns all the rows in a single array.
*
* One can also retrieve the rows of data in CDbDataReader by using foreach:
*
* foreach($reader as $row)
* // $row represents a row of data
*
* Since CDbDataReader is a forward-only stream, you can only traverse it once.
*
* It is possible to use a specific mode of data fetching by setting
* {@link setFetchMode FetchMode}. See {@link http://www.php.net/manual/en/function.PDOStatement-setFetchMode.php}
* for more details.
*
* @author Qiang Xue
* @version $Id: CDbDataReader.php 3204 2011-05-05 21:36:32Z alexander.makarow $
* @package system.db
* @since 1.0
*/
class CDbDataReader extends CComponent implements Iterator, Countable
{
private $_statement;
private $_closed = false;
private $_row;
private $_index = -1;
/**
* Constructor.
* @param CDbCommand $command the command generating the query result
*/
public function __construct(CDbCommand $command)
{
$this->_statement = $command->getPdoStatement();
$this->_statement->setFetchMode(PDO::FETCH_ASSOC);
}
/**
* 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 mixed $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 integer $dataType Data type of the parameter
* @see http://www.php.net/manual/en/function.PDOStatement-bindColumn.php
*/
public function bindColumn($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 mixed $mode fetch mode
* @see http://www.php.net/manual/en/function.PDOStatement-setFetchMode.php
*/
public function setFetchMode($mode)
{
$params = func_get_args();
call_user_func_array(array($this->_statement, 'setFetchMode'), $params);
}
/**
* Advances the reader to the next row in a result set.
* @return array|false 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 integer $columnIndex zero-based column index
* @return mixed|false the column of the current row, false if no more row available
*/
public function readColumn($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 $fields Elements of this array are passed to the constructor
* @return mixed|false the populated object, false if no more row of data available
*/
public function readObject($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 $this->_statement->fetchAll();
}
/**
* Advances the reader to the next result when reading the results of a batch of statements.
* This method is only useful when there are multiple result sets
* returned by the query. Not all DBMS support this feature.
* @return boolean Returns true on success or false on failure.
*/
public function nextResult()
{
if (($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 attemps after this method call are unpredictable.
*/
public function close()
{
$this->_statement->closeCursor();
$this->_closed = true;
}
/**
* whether the reader is closed or not.
* @return boolean 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 integer 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 integer number of rows contained in the result.
*/
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 integer the number of columns in the result set.
*/
public function getColumnCount()
{
return $this->_statement->columnCount();
}
/**
* Resets the iterator to the initial state.
* This method is required by the interface Iterator.
* @throws CException if this method is invoked twice
*/
public function rewind()
{
if ($this->_index < 0)
{
$this->_row = $this->_statement->fetch();
$this->_index = 0;
}
else
throw new CDbException(Yii::t('yii', 'CDbDataReader cannot rewind. It is a forward-only reader.'));
}
/**
* Returns the index of the current row.
* This method is required by the interface Iterator.
* @return integer the index of the current row.
*/
public function key()
{
return $this->_index;
}
/**
* Returns the current row.
* This method is required by the interface Iterator.
* @return mixed the current row.
*/
public function current()
{
return $this->_row;
}
/**
* Moves the internal pointer to the next row.
* This method is required by the interface Iterator.
*/
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 boolean whether there is a row of data at current position.
*/
public function valid()
{
return $this->_row !== false;
}
}