YII2 Insert something in array made by arrayhelper::map() -

how insert or push existing array?

i have code...

$brgys=arrayhelper::map(libbrgy::find() ->where(['city_code'=>$model->city_code]) ->all(),'brgy_code','brgy_name');  

the result is..

array(4) { [166816001]=> string(7) "bagyang"  [166816002]=> string(5) "baras"  [166816003]=> string(8) "bitaugan"  [166816004]=> string(7) "bolhoon"  } 

how add empty value make following...

array(4) { [166816001]=> string(7) "bagyang"  [166816002]=> string(5) "baras"  [166816003]=> string(8) "bitaugan"  [166816004]=> string(7) "bolhoon" ['']=>"" } 

so in html form have this..

<select id="tblspbub-brgy_code" class="form-control" name="tblspbub[brgy_code]"> <option value="166816001">bagyang</option> <option value="166816002">baras</option> <option value="166816003">bitaugan</option> <option value="166816004">bolhoon</option> <option value=""></option> </select> 

no need modify array achieve this.

drop-down list has special option called prompt.

<?= $form->field($model, 'code')->dropdownlist($items, ['prompt' => '']) ?> 

it render additional option empty value in select given name.

you can read more here.