PHP无限级分类转换为树型结构

php无限级分类转换为树型结构

代码如下：

public function updateCache($tip = 1) {

    $_tree = array();
    $results  = D( 'enum' )->field( 'id,pid,title,name,value' )->select( array( 'index' => 'id' ) );
    
    if(!empty($results)){
        foreach ( $results as $key=> $value ) {
            if ( isset( $results[ $value['pid'] ] ) ) {
                $results[ $value['pid'] ]['_'][ $key ] = &$results[ $value['id'] ];
            }else{
                $_tree[ $key ] = & $results[$value['id']];
            }
        }
    }
    
    S('enum',$_tree);
    if($tip == 1){
        $this->ajaxSuccess('缓存成功！');
    }

}