dev.iordanov.net » database http://dev.iordanov.net Sun, 31 May 2009 18:07:26 +0000 http://wordpress.org/?v=2.8.6 en hourly 1 extending Zend_Db_Table to create NestedSet models http://dev.iordanov.net/archives/8 http://dev.iordanov.net/archives/8#comments Sun, 13 Jul 2008 12:00:09 +0000 ivan http://dev.iordanov.net/?p=8 Last days I’ve been trying to customize Zend’s Framework. My goal is to create simpler models. Currently I’m making some db models that handle stuff around wide used designs. Such design is the Nested Set model. It is an adjacent list realized in SQL as a tree. You can find a good introduction to nested sets at mysql developer zone.

Now let’s create a basic table.

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CREATE TABLE nested_table (
    `nested_table_id` int UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
    `nested_table_left` int UNSIGNED NOT NULL,
    `nested_table_right` int UNSIGNED NOT NULL,
    `nested_table_name` varchar(60) NOT NULL
);

And now let’s create a model that will work with this table.

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class NestedTable extends Custom_Db_Nestedset {
    //basic mapping
    protected $_name     = "nested_table"; //table name
    protected $_primary  = "nested_table_id"; //primary key
    protected $_left     = "nested_table_left"; //left column
    protected $_right    = "nested_table_right"; //right column
    protected $_toString = "nested_table_name"; //used when retrieving tree. if not set primary key will be used
}

And that’s it. Now we have class that work as a nested set. Here is example controller.

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class NestedController extends Zend_Controller_Action {
 
    public function testAction()
    {
        $table = new NestedTable;
        $root  = $table->createRoot(); //creating root node.
        $node1 = $table->insertAsFirstChildOf($root); //insert as first child of root category.
        $node2 = $table->insertAsNextSiblingOf($node1); //insert node next to given node. In our case next to node1.
        $node3 = $table->insertAsPrevSiblingOf($node2); //insert node before given node.
        $node4 = $table->insertAsLastChildOf($root); //insert node as last child of root category.
 
        $node2_1 = $table->insertAsFirstChildOf($node2); //go one level deeper.
        $table->deleteNode($node2);// delete node2 and his childs.
 
        $table->getTree(); //retrieve full tree (subtrees are still not supported)
    }
}

and here is the nested set class.

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<?php
 
/**
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license
 *
 * @category  Custom
 * @package  Custom_Db
 * @subpackage Nestedset
 * @copyright Copyright (c) 2008 Ivan Iordanov <ivan@iordanov.net>
 * @version  $Id: Nestedset.php 2008-06-06
 * @see    http://dev.mysql.com/tech-resources/articles/hierarchical-data.html
 */
 
 
/**
 * @see Zend_Db_Table
 */
require_once 'Zend/Db/Table.php';
 
/**
 * Class for SQL Nested set interface.
 *
 * @category  Custom
 * @package  Custom_Db
 * @subpackage Nestedset
 * @copyright Copyright (c) 2008 Ivan Iordanov (http://dev.iordanov.net)
 */
 
class Custom_Db_Nestedset extends Zend_Db_Table
{
 
    /**
    * left column in nested table
    *
    * @var String
    */
    protected $_left;
 
    /**
    * right column in nested table
    *
    * @var String
    */
    protected $_right;
 
    /**
    * Column to be retrieved with getTree method
    * If not set primary key will be used.
    *
    * @var String
    */
    protected $_toString;
 
    /**
    * Additional data to be inserted.
    *
    * @var Array
    */
    private  $_insertData = array();
 
    /**
    * constructor
    */
    public function __construct()
    {
        parent::__construct();
        if (!$this->_toString)
        {
            $this->_toString = $this->_primary[1];
        }
    }
 
    /**
    * Additional data to be inserted
    *
    * @param array
    * @access public
    */
    public function setInsertData(array $data)
    {
        $this->_insertData = $data;
    }
 
    /**
    * Retrieve whole tree
    *
    * @access public
    * @return array
    */
    public function getTree()
    {
        //todo: add custom node
        $ret = $this->_db->query("
            SELECT COUNT(parent.{$this->_primary[1]}) - 1 as depth, node.{$this->_toString}
            FROM {$this->_name} AS node, {$this->_name} AS parent
            WHERE node.{$this->_left}
            BETWEEN parent.{$this->_left}
            AND parent.{$this->_right}
            GROUP BY node.{$this->_primary[1]}
            ORDER BY node.{$this->_left}
        ");
        return $ret->fetchAll();
 
    }
 
    /**
    * Insert node as first child
    *
    * @param int
    * @access public
    * @return int
    */
    public function insertAsFirstChildOf($id)
    {
        $row = $this->retrieveData($id);
 
        $right = (int) $row->{$this->_right};
        $left  = (int) $row->{$this->_left};
 
        $this->_db->query("UPDATE {$this->_name} SET {$this->_right} = {$this->_right} + 2 WHERE {$this->_right} > {$left}");
        $this->_db->query("UPDATE {$this->_name} SET {$this->_left} = {$this->_left} + 2 WHERE {$this->_left} > {$left}");
 
        $data = array(
            $this->_left => $left + 1,
            $this->_right => $left + 2
        );
        $this->_insertData = array_merge($this->_insertData, $data);
 
        return $this->insert($this->_insertData);
    }
 
    /**
    * Insert node as last child
    *
    * @param int
    * @access public
    * @return int
    */
    public function insertAsLastChildOf($id)
    {
        $row = $this->retrieveData($id);
 
        $right = (int) $row->{$this->_right};
        $left  = (int) $row->{$this->_left};
 
        $this->_db->query("UPDATE {$this->_name} SET {$this->_right} = {$this->_right} + 2 WHERE {$this->_right} >= {$right}");
        $this->_db->query("UPDATE {$this->_name} SET {$this->_left} = {$this->_left} + 2 WHERE {$this->_left} > {$right}");
 
 
        $data = array(
            $this->_left => $right,
            $this->_right => $right + 1,
        );
        $this->_insertData = array_merge($this->_insertData, $data);
 
        return $this->insert($this->_insertData);
 
    }
 
    /**
    * Insert node as next sibling of given node
    *
    * @param int
    * @access public
    * @return int
    * @throws Exception
    */
    public function insertAsNextSiblingOf($id)
    {
        $row = $this->retrieveData($id);
        $right = (int) $row->{$this->_right};
        $left  = (int) $row->{$this->_left};
 
        if ($left === 1) {
            throw new Exception("Root node can't have siblings");
        }
 
        $this->_db->query("UPDATE {$this->_name} SET {$this->_right} = {$this->_right} + 2 WHERE {$this->_right} > {$right}");
        $this->_db->query("UPDATE {$this->_name} SET {$this->_left} = {$this->_left} + 2 WHERE {$this->_left} > {$right}");
 
 
        $data = array(
            $this->_left => $right+1,
            $this->_right => $right + 2,
        );
 
        $this->_insertData = array_merge($this->_insertData, $data);
        return $this->insert($this->_insertData);
 
    }
 
    /**
    * Insert node as prev sibling of given node
    *
    * @param int
    * @access public
    * @return int
    * @throws Exception
    */
    public function insertAsPrevSiblingOf($id)
    {
        $row = $this->retrieveData($id);
        $right = (int) $row->{$this->_right};
        $left  = (int) $row->{$this->_left};
 
        if ($left === 1) {
            throw new Exception("Root node can't have siblings");
        }
 
 
        $this->_db->query("UPDATE {$this->_name} SET {$this->_right} = {$this->_right} + 2 WHERE {$this->_right} > {$left}");
        $this->_db->query("UPDATE {$this->_name} SET {$this->_left} = {$this->_left} + 2 WHERE {$this->_left} >= {$left}");
 
 
        $data = array(
            $this->_left => $left,
            $this->_right => $left + 1,
        );
 
        $this->_insertData = array_merge($this->_insertData, $data);
        return $this->insert($this->_insertData);
    }
 
    /**
    * Delete node with it's child(s) and return affected rows
    *
    * @param int
    * @access public
    * @return int
    */
 
    public function deleteNode($id)
    {
        $row = $this->retrieveData($id);
        $right = (int) $row->{$this->_right};
        $left  = (int) $row->{$this->_left};
        $width = $right - $left + 1;
        $res = $this->_db->query("DELETE FROM {$this->_name} WHERE {$this->_left} BETWEEN {$left} AND {$right}");
 
        $this->_db->query("UPDATE {$this->_name} SET {$this->_right} = {$this->_right} - {$width} WHERE {$this->_right} > {$right}");
        $this->_db->query("UPDATE {$this->_name} SET {$this->_left} = {$this->_left} - {$width} WHERE {$this->_left} > {$right}");
 
        return $res->rowCount();
    }
 
    /**
    * Insert root node
    *
    * @access public
    * @return int
    */
    public function createRoot()
    {
 
        $data = array(
            $this->_left => 1,
            $this->_right => 2
        );
        $this->_insertData = array_merge($this->_insertData, $data);
        return $this->insert($this->_insertData);
    }
 
    /**
    * Insert node
    *
    * @param int
    * @access private
    * @return Zend_Db_Row
    */
    private function retrieveData($id)
    {
        $select = $this->select()->where($this->_primary[1] .' = ?', $id);
        return $this->fetchRow($select);
    }
}

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