What to do if dropDownList = null?

Question

Yii

<?= $form->field($model, 'teams')->dropDownList($teams, [
                    'multiple' => 'true',
                ]); ?>

But if the teams is empty, the error Invalid argument supplied for foreach () falls out.
How can I display an empty multi select, then I add elements to it in js

Answer 1

<?= $form->field($model, 'teams')->dropDownList(!empty($teams) ? $teams : [], [
                    'multiple' => 'true',
                ]); ?>