add an iterator for objects with a get_rows method

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Ralf Becker 2020-01-13 14:41:46 +01:00
parent 0f64b4c740
commit f7c653832f

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@ -0,0 +1,188 @@
<?php
/**
* EGroupware generalized SQL Storage Object: Iterator for get_rows
*
* @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
* @package api
* @subpackage storage
* @link http://www.egroupware.org
* @author Ralf Becker <rb@egroupware.org>
* @copyright 2020 by Ralf Becker <rb@egroupware.org>
*/
namespace EGroupware\Api\Storage;
use EGroupware\Api;
/**
* Iterator using a get_rows method and querying it in chunks instead of all rows as once
*
* You should use a consisten sorting eg. by id, in case rows change while the iterator is instanciated!
*
* Instead of ($query['num_rows']=-1, $query['start']=0):
*
* $storage->get_rows($query, $rows, $readonlys);
*
* Use:
*
* $rows = new RowsIterator($storage, $query);
*/
class RowsIterator implements \Iterator
{
/**
* Reference of Storage\Base class or other object with a get_rows method
*
* @var Base
*/
protected $storage;
/**
* query parameter for get_rows
*
* @var array
*/
protected $query;
/**
* name of (unique) key in row or null to use $this->start + key returned by get_rows
*
* @var string
*/
protected $key;
/**
* current chunk
*
* @var array
*/
protected $rows;
/**
* Start value for callback
*
* @var int
*/
protected $start=0;
/**
* Number of rows queried from get_rows in one call
*/
const CHUNK_SIZE = 500;
/**
* Log calls via error_log()
*
* @var boolean
*/
public $debug = false;
/**
* Constructor
*
* @param Base $storage only requirement is class to have a get_rows method
* @param array $query query parameter for get_rows
* @param string $key =null name of (unique) key in row, default use $this->start + key from get_rows
*/
public function __construct($storage, array $query, $key=null)
{
if (!is_object($storage) || !method_exists($storage, 'get_rows'))
{
throw new Api\Exception\WrongParameter("\$storage parameter needs to be object with a get_rows method!");
}
$this->storage = $storage;
$this->query = $query;
$this->key = $key;
}
/**
* Return the current element
*
* @return array
*/
public function current()
{
if ($this->debug) error_log(__METHOD__."() returning ".array2string(current($this->rows)));
return current($this->rows);
}
/**
* Return the key of the current element
*
* @return int|string
*/
public function key()
{
$current = current($this->rows);
$key = !empty($this->key) ? $current[$this->key] : $this->start + key($this->rows);
if ($this->debug) error_log(__METHOD__."() returning ".array2string($key));
return $key;
}
/**
* Move forward to next element (called after each foreach loop)
*/
public function next()
{
if (next($this->rows) !== false)
{
if ($this->debug) error_log(__METHOD__."() returning TRUE");
return true;
}
// check if previous query gave less then CHUNK_SIZE entries --> we're done
if ($this->start && count($this->rows) < self::CHUNK_SIZE)
{
if ($this->debug) error_log(__METHOD__."() returning FALSE (no more entries)");
return false;
}
// try query further rows via get_rows method and store result in $this->rows
$readonlys = null;
$this->query['start'] = $this->start;
$this->query['num_rows'] = self::CHUNK_SIZE;
$this->storage->get_rows($this->query, $this->rows, $readonlys);
// remove non-rows returned (sel_options and the like, or leading false old eTemplate required)
foreach($this->rows as $key => $row)
{
if (!is_int($key) || !is_array($row))
{
unset($this->rows[$key]);
}
}
if (!is_array($this->rows) || !($entries = count($this->rows)))
{
if ($this->debug) error_log(__METHOD__."() returning FALSE (no more entries)");
return false; // no further entries
}
$this->start += self::CHUNK_SIZE;
reset($this->rows);
if ($this->debug) error_log(__METHOD__."() this->start=$this->start, entries=$entries, count(this->files)=".count($this->rows)." returning ".array2string(current($this->rows) !== false));
return current($this->rows) !== false;
}
/**
* Rewind the Iterator to the first element (called at beginning of foreach loop)
*/
public function rewind()
{
if ($this->debug) error_log(__METHOD__."()");
$this->start = 0;
$this->rows = [];
if (!$this->rows) $this->next(); // otherwise valid will return false and nothing get returned
reset($this->rows);
}
/**
* Checks if current position is valid
*
* @return boolean
*/
public function valid ()
{
if ($this->debug) error_log(__METHOD__."() returning ".array2string(current($this->rows) !== false));
return current($this->rows) !== false;
}
}