How to make the select parameter empty initially?

Question

Yii

I use the search Model for searching. In order not to write the category for the search by hand, I did it like this.

<?= $form->field($model, 'category_id')->dropDownList(ArrayHelper::map(Category::find()->all(), 'id','name'),['style'=>'font-family: \'Exo 2\', sans-serif; color: #0f0f0f; font-size:17px'])->label('Отделение')?>

But the bottom line is that the first branch of the list is always active. That is, it will already search by this parameter. But how to make it so that the parameter was not there initially?

Answer 1

<?= $form->field($model, 'category_id')->dropDownList(['' => 'Укажите отделение'] + ArrayHelper::map(Category::find()->all(), 'id','name'),['style'=>'font-family: \'Exo 2\', sans-serif; color: #0f0f0f; font-size:17px'])->label('Отделение')?>

Answer 2

https://stackoverflow.com/questions/17060177/yii2-...