如何将空白字段添加到activeDropDownList yii2？

Question

i have a drop down list using ArrayHelper::map as below code:

 <?= Html::activeDropDownList($model2, 'expert_id', ArrayHelper::map(Experts::find()->all(), 'username', 'username')) ?> 

that works correctly but i want to add empty fields or other favorite fields ... how can i do that?

Answer 1

Try to use array merge

 <?= Html::activeDropDownList($model2, 'expert_id',
  array_merge(array('val1'=>'val1'), ArrayHelper::map(Experts::find()->all(), 'username', 'username'))) ?>

Answer 2

cleaner: (if you just want to add empty fields)

<?= Html::activeDropDownList($model2, 'expert_id',
   ArrayHelper::map(Experts::find()->all(), 'username', 'username')), array('placeholder'=>'') ?>