平时开发中或多或少不可避免会遇到无限极分类的问题,因为效率、逻辑等问题也一直使这类问题比较尖锐。今天我们以yii2框架为基础,栏目无限极为例,对这个问题进行一个简单的处理。
首先我们有一张栏目数据表 tree
表结构如下图(原文有图)
看上去表结构很简单。
我们插入几条测试数据
INSERT INTO `tree` (`id`, `parent_id`, `name`) VALUES (1, 0, 'A'), (2, 0, 'B'), (3, 1, 'a'), (4, 3, 'aa'), (5, 2, 'b'), (6, 4, 'aaa');
树形结构大致如下
|A |--a |----aa |------aaa |B |--b
这也正是我们所需要的数据结构形式,下面我们来看看如何处理才能够得到所需要的结果。
我们前面也说了,以yii2为基础,因此我们的写法也按照面向对象的规则来
class tree { //访问index查看树形结构 public function actionIndex () { $data = self::getTree(); //为了方便测试,我们这里以json格式输出 \Yii::$app->response->format = \yii\web\Response::FORMAT_JSON; return $data; } //获取树 public static function getTree () { //这里我们直接获取所有的数据,然后通过程序进行处理 //在无限极分类中最忌讳的是对数据库进行层层操作,也就很容易造成内存溢出 //最后电脑死机的结果 $data = static::find()->all(); return self::_generateTree($data); } //生成树 private static function _generateTree ($data, $pid = 0) { $tree = []; if ($data && is_array($data)) { foreach($data as $v) { if($v['parent_id'] == $pid) { $tree[] = [ 'id' => $v['id'], 'name' => $v['name'], 'parent_id' => $v['parent_id'], 'children' => self::_generateTree($data, $v['id']), ]; } } } return $tree; } }
我们访问下tree/index看看,效果图如下
这样我们可以看到一个很清晰的树形结构图,也就是我们最终所需要的。

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