yii2.0之GridView自定义按钮和链接用法

<?= gridview::widget([
        'dataprovider' => $dataprovider,
        //'filtermodel' => $searchmodel,
        'columns' => [
            ['class' => 'yii\grid\serialcolumn'],
            //显示的字段
            //code的值
            ['attribute'=>'这是测试code','value'=>function(){return 'abc';}],
            'name',
            'population',
           
            ['class' => 'yii\grid\actioncolumn','header' => '操作',],
            [
                'label'=>'更多操作',
                'format'=>'raw',
                'value' => function($data){
                    $url = "http://www.baidu.com";
                    return html::a('添加权限组', $url, ['title' => '审核']);
                }
            ]       
        ],
    ]); ?>