yii框架无限极分类的做法

protected function subtree($arr,$id=0,$lev=1){
        $subs = array(); // 子孙数组
        foreach($arr as $v) {
            if($v[‘parent_id‘] == $id) {
                $v[‘lev‘] = $lev;
                $subs[] = $v; // 举例说找到array(‘id‘=>1,‘name‘=>‘安徽‘,‘parent‘=>0),
                $subs = array_merge($subs,$this->subtree($arr,$v[‘cat_id‘],$lev+1));
            }
        }
        return $subs;
    }

public function actionCreate()
    {
        $model = new EcsCategory();
        $query = new \yii\db\Query();
        $query->select(‘*‘)
            ->from(‘ecs_category‘);
        $command = $query->createCommand();
        $res=$command->queryAll();
        $tree = $this->subtree($res,0,1);
        foreach($tree as $k=> $v) {
            $tree[$k][‘new_cat_name‘]=str_repeat(‘--‘,$v[‘lev‘]).$v[‘cat_name‘].str_repeat(‘--‘,$v[‘lev‘]);  //str_repeat — 重复一个字符串
        }
        $arr=array(
            ‘new_cat_name‘=>‘顶级分类‘,
            ‘cat_id‘=>0
        );
        array_unshift($tree,$arr);
        if ($model->load(Yii::$app->request->post()) && $model->save()) {
            return $this->redirect([‘view‘, ‘id‘ => $model->cat_id]);
        } else {
            return $this->render(‘create‘, [
                ‘model‘ => $model,
                ‘data‘=>$tree,
            ]);
        }
    }

 use \yii\helpers\ArrayHelper;

<?= $form->field($model, ‘parent_id‘)->dropDownList(ArrayHelper::map($data,‘cat_id‘,‘new_cat_name‘) ,[‘prompt‘ => ‘请选择父级分类‘]) ?>