forked from extern/egroupware
add an iterator for objects with a get_rows method
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Ralf Becker
parent
0f64b4c740
commit
f7c653832f
188
api/src/Storage/RowsIterator.php
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188
api/src/Storage/RowsIterator.php
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<?php
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/**
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* EGroupware generalized SQL Storage Object: Iterator for get_rows
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*
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* @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
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* @package api
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* @subpackage storage
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* @link http://www.egroupware.org
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* @author Ralf Becker <rb@egroupware.org>
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* @copyright 2020 by Ralf Becker <rb@egroupware.org>
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*/
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namespace EGroupware\Api\Storage;
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use EGroupware\Api;
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/**
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* Iterator using a get_rows method and querying it in chunks instead of all rows as once
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*
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* You should use a consisten sorting eg. by id, in case rows change while the iterator is instanciated!
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*
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* Instead of ($query['num_rows']=-1, $query['start']=0):
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*
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* $storage->get_rows($query, $rows, $readonlys);
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*
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* Use:
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*
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* $rows = new RowsIterator($storage, $query);
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*/
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class RowsIterator implements \Iterator
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{
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/**
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* Reference of Storage\Base class or other object with a get_rows method
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*
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* @var Base
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*/
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protected $storage;
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/**
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* query parameter for get_rows
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*
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* @var array
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*/
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protected $query;
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/**
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* name of (unique) key in row or null to use $this->start + key returned by get_rows
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*
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* @var string
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*/
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protected $key;
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/**
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* current chunk
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*
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* @var array
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*/
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protected $rows;
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/**
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* Start value for callback
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*
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* @var int
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*/
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protected $start=0;
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/**
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* Number of rows queried from get_rows in one call
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*/
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const CHUNK_SIZE = 500;
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/**
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* Log calls via error_log()
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*
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* @var boolean
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*/
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public $debug = false;
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/**
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* Constructor
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*
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* @param Base $storage only requirement is class to have a get_rows method
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* @param array $query query parameter for get_rows
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* @param string $key =null name of (unique) key in row, default use $this->start + key from get_rows
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*/
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public function __construct($storage, array $query, $key=null)
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{
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if (!is_object($storage) || !method_exists($storage, 'get_rows'))
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{
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throw new Api\Exception\WrongParameter("\$storage parameter needs to be object with a get_rows method!");
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}
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$this->storage = $storage;
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$this->query = $query;
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$this->key = $key;
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}
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/**
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* Return the current element
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*
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* @return array
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*/
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public function current()
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{
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if ($this->debug) error_log(__METHOD__."() returning ".array2string(current($this->rows)));
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return current($this->rows);
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}
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/**
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* Return the key of the current element
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*
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* @return int|string
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*/
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public function key()
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{
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$current = current($this->rows);
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$key = !empty($this->key) ? $current[$this->key] : $this->start + key($this->rows);
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if ($this->debug) error_log(__METHOD__."() returning ".array2string($key));
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return $key;
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}
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/**
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* Move forward to next element (called after each foreach loop)
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*/
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public function next()
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{
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if (next($this->rows) !== false)
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{
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if ($this->debug) error_log(__METHOD__."() returning TRUE");
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return true;
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}
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// check if previous query gave less then CHUNK_SIZE entries --> we're done
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if ($this->start && count($this->rows) < self::CHUNK_SIZE)
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{
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if ($this->debug) error_log(__METHOD__."() returning FALSE (no more entries)");
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return false;
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}
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// try query further rows via get_rows method and store result in $this->rows
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$readonlys = null;
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$this->query['start'] = $this->start;
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$this->query['num_rows'] = self::CHUNK_SIZE;
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$this->storage->get_rows($this->query, $this->rows, $readonlys);
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// remove non-rows returned (sel_options and the like, or leading false old eTemplate required)
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foreach($this->rows as $key => $row)
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{
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if (!is_int($key) || !is_array($row))
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{
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unset($this->rows[$key]);
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}
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}
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if (!is_array($this->rows) || !($entries = count($this->rows)))
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{
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if ($this->debug) error_log(__METHOD__."() returning FALSE (no more entries)");
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return false; // no further entries
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}
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$this->start += self::CHUNK_SIZE;
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reset($this->rows);
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if ($this->debug) error_log(__METHOD__."() this->start=$this->start, entries=$entries, count(this->files)=".count($this->rows)." returning ".array2string(current($this->rows) !== false));
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return current($this->rows) !== false;
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}
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/**
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* Rewind the Iterator to the first element (called at beginning of foreach loop)
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*/
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public function rewind()
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{
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if ($this->debug) error_log(__METHOD__."()");
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$this->start = 0;
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$this->rows = [];
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if (!$this->rows) $this->next(); // otherwise valid will return false and nothing get returned
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reset($this->rows);
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}
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/**
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* Checks if current position is valid
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*
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* @return boolean
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*/
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public function valid ()
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{
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if ($this->debug) error_log(__METHOD__."() returning ".array2string(current($this->rows) !== false));
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return current($this->rows) !== false;
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}
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}
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