src/validators/StateValidator.php
protected function validateValue($value)
    {
        if (State::find()->andWhere(['id' => $value])->exists() === false) {
            return Yii::t('location', 'State with id {[id]} doesn\'t exist', [
                        'id' => $value
            ]);
        }
    }
protected function validateValue($value)
    {
        if (State::find()->andWhere(['id' => $value])->exists() === false) {
            return Yii::t('location', 'State with id {[id]} doesn\'t exist', [
                        'id' => $value
            ]);
        }
    }
@inheritdoc

Checks if the given region id exists.