zen cart 类：category_tree

zen cart 类 category_tree 位于 /includes/classes/category_tree.php 文件中，主要的作用是，产生商品分类的树状目录。

<?php
/**
 * category_tree Class.
 *
 * @package classes
 * @copyright Copyright 2003-2006 Zen Cart Development Team
 * @copyright Portions Copyright 2003 osCommerce
 * @license http://www.zen-cart.com/license/2_0.txt GNU Public License V2.0
 * @version $Id: category_tree.php 3041 2006-02-15 21:56:45Z wilt $
 */
if (!defined('IS_ADMIN_FLAG')) { //防止非法访问
  die('Illegal Access');
}
/**
 * category_tree Class.
 * This class is used to generate the category tree used for the categories sidebox
 *
 * @package classes
 */
 // 继承 base 基本类
class category_tree extends base {
	 // zen_category_tree 方法，传递一个参数：$product_type，默认值是：all
  function zen_category_tree($product_type = "all") {
    global $db, $cPath, $cPath_array; // 定义3个 global 变量。$cPath 和 $cPath_array 可以在 /includes/init_includes/init_category_path.php 文件中找到
    // 如果 $product_type 不是 'all'，则执行以下代码（因为默认值是 all，所以如果不传递任何参数，则以下代码不会被执行）
    if ($product_type != 'all') { 
      // 将一条 sql 语句赋值给 $sql 变量。该语句的作用是
      	// 从 product_types 数据库表中选择 type_master_type 字段，必须是和 $product_type 相等的 type_master_type 字段
      $sql = "select type_master_type from " . TABLE_PRODUCT_TYPES . "
                where type_master_type = " . $product_type . "";
      // 执行 $sql 语句
      $master_type_result = $db->Execute($sql);
      // 从 $master_type_result 对象中得到 type_master_type 字段值
      $master_type = $master_type_result->fields['type_master_type'];
    }
    
    $this->tree = array(); // 定义一个类成员 tree 为数组，$this->tree 是类变量的表示方法，如果不在类里面定义，其实就是 $tree
    if ($product_type == 'all') { // 如果 $product_type 的值等于 all
      // 将一条 sql 语句赋值给 $categories_query
       // 该语句的作用是多表查询 categories 和 categories_description 数据库表
       	// 返回 categories 表中的 categories_id，parent_id，categories_image 字段；categories_description 表中的 categories_name 字段
       	// 返回结果必须符合：parent_id = 0，同一个 categories_id，language_id = $_SESSION['languages_id'] 以及 categories_status= 1
       	// 返回结果按照 categories_name 排序
      $categories_query = "select c.categories_id, cd.categories_name, c.parent_id, c.categories_image
                             from " . TABLE_CATEGORIES . " c, " . TABLE_CATEGORIES_DESCRIPTION . " cd
                             where c.parent_id = 0
                             and c.categories_id = cd.categories_id
                             and cd.language_id='" . (int)$_SESSION['languages_id'] . "'
                             and c.categories_status= 1
                             order by sort_order, cd.categories_name";
    } else { // 如果 $product_type 不为 all，则执行以下代码
      // 将一条 sql 语句赋值给 $categories_query，代码分析如上 
      $categories_query = "select ptc.category_id as categories_id, cd.categories_name, c.parent_id, c.categories_image
                             from " . TABLE_CATEGORIES . " c, " . TABLE_CATEGORIES_DESCRIPTION . " cd, " . TABLE_PRODUCT_TYPES_TO_CATEGORY . " ptc
                             where c.parent_id = 0
                             and ptc.category_id = cd.categories_id
                             and ptc.product_type_id = " . $master_type . "
                             and c.categories_id = ptc.category_id
                             and cd.language_id=" . (int)$_SESSION['languages_id'] ."
                             and c.categories_status= 1
                             order by sort_order, cd.categories_name";
    }
    // 执行 $categories_query 语句
    $categories = $db->Execute($categories_query, '', true, 150);
    while (!$categories->EOF)  { // 查询结果没有出尽，则循环执行以下语句
      // 把查询得到的 categories_name，parent_id，categories_id，categories_image 和其它几个值合成一个数组，赋值给 $this->tree(X)
      // 这个 X 就是：$categories->fields['categories_id'] 即商品分类的 id
      $this->tree[$categories->fields['categories_id']] = array(
      																			'name' => $categories->fields['categories_name'],
      																			'parent' => $categories->fields['parent_id'],
      																			'level' => 0,
      																			'path' => $categories->fields['categories_id'],
      																			'image' => $categories->fields['categories_image'],
      																			'next_id' => false
      																		);
      if (isset($parent_id)) {  // 如果存在 $parent_id 这个变量
      	// 把查询得到的 categories_id 赋值给 $this->tree[X]['next_id']，在上面的代码中，next_id 这个值默认是 false
        $this->tree[$parent_id]['next_id'] = $categories->fields['categories_id'];
      }
      // 把查询得到的 categories_id 赋值给 $parent_id;
      $parent_id = $categories->fields['categories_id'];
      if (!isset($first_element)) { // 如果不存在 $first_element 这个变量
      	// 将查询得到的 categories_id 赋值给 $first_element
        $first_element = $categories->fields['categories_id'];
      }
      $categories->MoveNext(); // $categories 往后移动一个指针
    }
    
    if (zen_not_null($cPath)) { // 如果 $cPath 不为空
      $new_path = ''; 
      reset($cPath_array); // 把 $cPath_array 数组的内部指针指向第一个元素，并返回这个元素的值
      while (list($key, $value) = each($cPath_array)) { // 把 $cPath_array 元素为 $key $value 变量赋值
        unset($parent_id); // 销毁 $parent_id 变量
        unset($first_id); // 销毁 $first_id 变量
        if ($product_type == 'all') { // 如果 $product_type 的值等于 all
          // sql 查询语句
          $categories_query = "select c.categories_id, cd.categories_name, c.parent_id, c.categories_image
                               from " . TABLE_CATEGORIES . " c, " . TABLE_CATEGORIES_DESCRIPTION . " cd
                               where c.parent_id = " . (int)$value . "
                               and c.categories_id = cd.categories_id
                               and cd.language_id=" . (int)$_SESSION['languages_id'] . "
                               and c.categories_status= 1
                               order by sort_order, cd.categories_name";
        } else { // 如果 $product_type 的值不为 all
          /*
          $categories_query = "select ptc.category_id as categories, cd.categories_name, c.parent_id, c.categories_image
          from " . TABLE_CATEGORIES . " c, " . TABLE_CATEGORIES_DESCRIPTION . " cd, " . TABLE_PRODUCT_TYPES_TO_CATEGORY . " ptc
          where c.parent_id = '" . (int)$value . "'
          and ptc.category_id = cd.categories_id
          and ptc.product_type_id = '" . $master_type . "'
          and cd.language_id='" . (int)$_SESSION['languages_id'] . "'
          and c.categories_status= '1'
          order by sort_order, cd.categories_name";
          */
          // sql 查询语句，可以和上一条比较，看有什么不同
          $categories_query = "select ptc.category_id as categories_id, cd.categories_name, c.parent_id, c.categories_image
                             from " . TABLE_CATEGORIES . " c, " . TABLE_CATEGORIES_DESCRIPTION . " cd, " . TABLE_PRODUCT_TYPES_TO_CATEGORY . " ptc
                             where c.parent_id = " . (int)$value . "
                             and ptc.category_id = cd.categories_id
                             and ptc.product_type_id = " . $master_type . "
                             and c.categories_id = ptc.category_id
                             and cd.language_id=" . (int)$_SESSION['languages_id'] ."
                             and c.categories_status= 1
                             order by sort_order, cd.categories_name";
        }
        $rows = $db->Execute($categories_query); // 执行 $categories_query 查询语句
        if ($rows->RecordCount()>0) { // 如果 $rows 对象中的 RecordCount() 方法返回的结果大于0
        	
          $new_path .= $value; // 将 $cPath_array 数组的值，累计赋值给 $new_path
          
          while (!$rows->EOF) { // 如果 $rows 没出尽
          	
            $this->tree[$rows->fields['categories_id']] = array(
            																	'name'   => $rows->fields['categories_name'],
           													 					'parent'  => $rows->fields['parent_id'],
            																	'level'     => $key+1,
            																	'path'     => $new_path . '_' . $rows->fields['categories_id'],
            																	'image'   => $categories->fields['categories_image'],
            																	'next_id' => false
            																);
            if (isset($parent_id)) {
              $this->tree[$parent_id]['next_id'] = $rows->fields['categories_id'];
            }
            $parent_id = $rows->fields['categories_id'];
            if (!isset($first_id)) {
              $first_id = $rows->fields['categories_id'];
            }
            $last_id = $rows->fields['categories_id'];
            $rows->MoveNext();
          }
          $this->tree[$last_id]['next_id'] = $this->tree[$value]['next_id'];
          $this->tree[$value]['next_id'] = $first_id;
          $new_path .= '_';
        } else {
          break;
        }
      }
    }
    $row = 0;
    return $this->zen_show_category($first_element, $row);
  }
  function zen_show_category($counter,$ii) {
    global $cPath_array;
    $this->categories_string = "";
    for ($i=0; $i<$this->tree[$counter]['level']; $i++) {
      if ($this->tree[$counter]['parent'] != 0) {
        $this->categories_string .= CATEGORIES_SUBCATEGORIES_INDENT;
      }
    }

    if ($this->tree[$counter]['parent'] == 0) {
      $cPath_new = 'cPath=' . $counter;
      $this->box_categories_array[$ii]['top'] = 'true';
    } else {
      $this->box_categories_array[$ii]['top'] = 'false';
      $cPath_new = 'cPath=' . $this->tree[$counter]['path'];
      $this->categories_string .= CATEGORIES_SEPARATOR_SUBS;
    }
    $this->box_categories_array[$ii]['path'] = $cPath_new;
    if (isset($cPath_array) && in_array($counter, $cPath_array)) {
      $this->box_categories_array[$ii]['current'] = true;
    } else {
      $this->box_categories_array[$ii]['current'] = false;
    }
    // display category name
    $this->box_categories_array[$ii]['name'] = $this->categories_string . $this->tree[$counter]['name'];
    // make category image available in case needed
    $this->box_categories_array[$ii]['image'] = $this->tree[$counter]['image'];
    if (zen_has_category_subcategories($counter)) {
      $this->box_categories_array[$ii]['has_sub_cat'] = true;
    } else {
      $this->box_categories_array[$ii]['has_sub_cat'] = false;
    }
    if (SHOW_COUNTS == 'true') {
      $products_in_category = zen_count_products_in_category($counter);
      if ($products_in_category > 0) {
        $this->box_categories_array[$ii]['count'] = $products_in_category;
      } else {
        $this->box_categories_array[$ii]['count'] = 0;
      }
    }
    if ($this->tree[$counter]['next_id'] != false) {
      $ii++;
      $this->zen_show_category($this->tree[$counter]['next_id'], $ii);
    }
    return $this->box_categories_array;
  }
}
?>