如何在Yii Model的验证规则Rules中区分场景？

namespace app\models;



use yii\db\ActiveRecord;



class User extends ActiveRecord

{

    [b]const SCENARIO_LOGIN = 'login';

    const SCENARIO_REGISTER = 'register';

[/b]



    public function scenarios()

    {

        return [

            self::SCENARIO_LOGIN => ['username', 'password'],

            self::SCENARIO_REGISTER => ['username', 'email', 'password'],

        ];

    }

}

public function rules()

{

    return [

        // username, email and password are all required in "register" scenario

        [['username', 'email', 'password'], 'required', [b]'on' => self::SCENARIO_REGISTER],

[/b]



        // username and password are required in "login" scenario

        [['username', 'password'], 'required',[b] 'on' => self::SCENARIO_LOGIN],

[/b]

    ];

}

// scenario is set as a property

$model = new User;

[b]$model->scenario[/b] = User::SCENARIO_LOGIN;



// scenario is set through configuration

$model = new User(['scenario' => User::SCENARIO_LOGIN]);