how to check yii2 relation is exist show controller

I have user and agency models

user have an agency model and can access whit $user->agency

now i want check in accessRule when relation is exist show my controller if that relation is null show an alert 'user->agency is null pealse create agency' and then pass the user to agency controller

in user model i have this relation :

public function getAgency(){
    return $this->hasOne(Agency::className(),['id'=>'agency_id'])
        ->viaTable(self::MAP_TABLE,['user_id'=>'id']);
}

and i have this accessRule components :

namespace common\components;

use common\models\User;

class AccessRule extends \yii\filters\AccessRule {

    /**
     * @inheritdoc
     */
    protected function matchRole($user)
    {
        if (empty($this->roles)) {
            return true;
        }
        foreach ($this->roles as $role) {

            if ($role == '?') {
                if ($user->getIsGuest()) {
                    return true;
                }
            }
            elseif (!$user->getIsGuest()) {


                $userObj = User::findOne(['id'=>$user->getId()]);

                if ($role == User::AGENCY_USER) {
                    if ( $userObj->agency_perm >= User::AGENCY_USER) {
                        return true;
                    }
                    // Check if the user is logged in, and the roles match
                } elseif ($role == User::AGENCY_MODERATOR) {
                    if ( $userObj->agency_perm >= User::AGENCY_MODERATOR) {
                        return true;
                    }
                    // Check if the user is logged in, and the roles match
                } elseif ($role == User::AGENCY_ADMIN) {
                    if ($userObj->agency_perm >= User::AGENCY_ADMIN) {
                        return true;
                    }
                    // Check if the user is logged in, and the roles match
                } elseif ($role == User::SUPER_USER) {
                    if ($userObj->super_user == User::SUPER_USER) {
                        return true;
                    }
                    // Check if the user is logged in, and the roles match
                } elseif (!$user->getIsGuest() && $role == $user->identity->role) {
                    return true;
                }

            }


        }

        return false;
    }
}

and use this in my controllers :

        'access' => [
            'class' => AccessControl::className(),
            // We will override the default rule config with the new AccessRule class
            'ruleConfig' => [
                'class' => AccessRule::className(),
            ],
            'rules' => [
                [
                    'allow' => true,
                    'roles' => [
                        User::SUPER_USER,
                    ],
                ],

            ],
        ],

In Yii access control, you can check user access by these approaches:

• Check in each action (not recommended)
• Controller construct() method
• Module/App middle-wares

You can check your custom access in this level, then choose to grant access or redirect him to another page.

In third way, you can access to your controller/action name, then decide what happens.