In-depth analysis of PHP infinite classification (tree class)

PHP has unlimited classification. You can find a lot of relevant information with just a Google search. The idea is quite popular and is also used more often. The classification table has at least three fields: id, pid and name. The id is automatically added to the table classification, and the pid is The parent category, name is the category name, which forms a tree. The following is the result set I got from querying the category table.

Copy code The code is as follows:

//模拟PHP无限分类查询结果
return array(
    array(
        'id'=>1,
        'pid'=>0,
        'name'=>'主页'
    ),
    array(
        'id'=>2,
        'pid'=>0,
        'name'=>'新闻'
    ),
    array(
        'id'=>3,
        'pid'=>0,
        'name'=>'媒体'
    ),
    array(
        'id'=>4,
        'pid'=>0,
        'name'=>'下载'
    ),
    array(
        'id'=>5,
        'pid'=>0,
        'name'=>'关于我们'
    ),
    array(
        'id'=>6,
        'pid'=>2,
        'name'=>'天朝新闻'
    ),
    array(
        'id'=>7,
        'pid'=>2,
        'name'=>'海外新闻'
    ),
    array(
        'id'=>8,
        'pid'=>6,
        'name'=>'州官新闻'
    ),
    array(
        'id'=>9,
        'pid'=>3,
        'name'=>'音乐'
    ),
    array(
        'id'=>10,
        'pid'=>3,
        'name'=>'电影'
    ),
    array(
        'id'=>11,
        'pid'=>3,
        'name'=>'小说'
    ),
    array(
        'id'=>12,
        'pid'=>9,
        'name'=>'铃声'
    ),
    array(
        'id'=>13,
        'pid'=>9,
        'name'=>'流行音乐'
    ),
    array(
        'id'=>14,
        'pid'=>9,
        'name'=>'古典音乐'
    ),
    array(
        'id'=>15,
        'pid'=>12,
        'name'=>'热门铃声'
    ),
    array(
        'id'=>16,
        'pid'=>12,
        'name'=>'搞笑铃声'
    ),
    array(
        'id'=>17,
        'pid'=>12,
        'name'=>'MP3铃声'
    ),
    array(
        'id'=>18,
        'pid'=>17,
        'name'=>'128K'
    ),
    array(
        'id'=>19,
        'pid'=>8,
        'name'=>'娱乐新闻'
    ),
    array(
'id'=>20,
 ;21,
 'pid'=>11,
 'name'=>'Martial Arts'
 ),
);
?>


 It’s popular, but the unlimited categories of class-related operations provided by those articles are a bit frustrating, and the database operations are also directly encapsulated. In other words, if other people want to use your class, they also have to build the same table as you. It's really disgusting. Since the project will use it, I wrote a PHP infinite classification class (also called a tree class). There is no database operation. I only need to pass in the result set, which is a tree array, when instantiating it. Then execute the leaf method or navi method to get the desired result. Please see the source code below. After reading it, I will provide the corresponding template recursive method of the smarty template engine. 

Copy code

The code is as follows:

/**
 * Tree tree class (unlimited classification) 
 *
 * @author Kvoid
 * @copyright http://kvoid.com
 * @version 1.0
 * @access public 
 * @example
 * $tree= new Tree($result);
 * $arr=$tree->leaf(0);
 * $nav=$tree->navi (15);
*/
class Tree {
    private $result;
    private $tmp;
    private $arr;
    private $already = array();
    /**
 * Constructor 
 *
 * @param array $result Tree data table result set 
 * @param array $fields Tree data table fields, array (category id, parent id) 
 * @param integer $root The parent id of the top category
*/
    public function __construct($result, $fields = array('id', 'pid'), $root = 0) {
        $this->result = $result;
        $this->fields = $fields;
        $this->root = $root;
        $this->handler();
    }
    /**
 * Tree data table result set processing 
*/
    private function handler() {
        foreach ($this->result as $node) {
            $tmp[$node[$this->fields[1]]][] = $node;
        }
        krsort($tmp);
        for ($i = count($tmp); $i > 0; $i--) {
            foreach ($tmp as $k => $v) {
                if (!in_array($k, $this->already)) {
                    if (!$this->tmp) {
                        $this->tmp = array($k, $v);
                        $this->already[] = $k;
                        continue;
                    } else {
                        foreach ($v as $key => $value) {
                            if ($value[$this->fields[0]] == $this->tmp[0]) {
                                $tmp[$k][$key]['child'] = $this->tmp[1];
                                $this->tmp = array($k, $tmp[$k]);
                            }
                        }
                    }
                }
            }
            $this->tmp = null;
        }
        $this->tmp = $tmp;
    }
    /**
 * Reverse recursion 
*/
    private function recur_n($arr, $id) {
        foreach ($arr as $v) {
            if ($v[$this->fields[0]] == $id) {
                $this->arr[] = $v;
                if ($v[$this->fields[1]] != $this->root) $this->recur_n($arr, $v[$this->fields[1]]);
            }
        }
    }
    /**
 * Forward recursion 
*/
    private function recur_p($arr) {
        foreach ($arr as $v) {
            $this->arr[] = $v[$this->fields[0]];
            if ($v['child']) $this->recur_p($v['child']);
        }
    }
    /**
 * Menu multi-dimensional array 
 *
 * @param integer $id category id
 * @return array Returns the branch, and returns the entire tree by default 
*/
    public function leaf($id = null) {
        $id = ($id == null) ? $this->root : $id;
        return $this->tmp[$id];
    }
    /**
 * Navigation one-dimensional array 
 *
 * @param integer $id category id
 * @return array Returns single-line classification until the top category 
*/
    public function navi($id) {
        $this->arr = null;
        $this->recur_n($this->result, $id);
        krsort($this->arr);
        return $this->arr;
    }
    /**
 * Scattered one-dimensional array 
 *
 * @param integer $id category id
 * @return array Returns all category ids under leaf
*/
    public function leafid($id) {
        $this->arr = null;
        $this->arr[] = $id;
        $this->recur_p($this->leaf($id));
        return $this->arr;
    }
}
?>

在smarty中的PHP无限分类的使用方法:
$result=$db->query(……);//这里查询得到结果集，注意结果集为数组
$tree= new Tree($result);
$arr=$tree->leaf(0);
$nav=$tree->navi(15);
$smarty->assign(‘arr',$arr);
$smarty->assign(‘nav',$nav);
$smarty->display(‘test.html');
在smarty模板中这样递归：

复制代码代码如下:

<{foreach $nav as $n}>
    <{if $n@iteration != $n@last}>
        <{$n.name}> ->
    <{else}>
        <{$n.name}>
    <{/if}>
<{/foreach}>



<{function name=menu}>
    
        <{foreach $data as $entry}>

                <{$entry.name}> <{*注意字段要改成自己的字段哦*}>
            <{if isset($entry.child)}>
                <{call name=menu data=$entry.child}>
            <{/if}>
            

        <{/foreach}>

<{/function}>
<{call name=menu data=$arr}> <{*注意在这里$arr才是模板变量*}>

当然，你也可以更改递归方法，用你想的标签不受拘束。HTML+PHP混编的递归方法这里就不贴了，我也懒得写，最讨厌混编，看着恶心，在这里推荐一下jake前辈的SpeedPHP框架，由于默认的引擎是smarty，我的这个PHP无限分类完全兼容SP框架。同样的，jquery的treeview插件和下拉菜单插件也完美支持。
对了，建议使用Smarty强大的缓存功能，缓存才是王道。

In-depth analysis of PHP infinite classification (tree class)_PHP tutorial