Boa noite! Preciso preencher automaticamente o campo de gestor, que está no mesmo dataset do prefixo selecionado no campo select.

html

<div class="form-group col-md-3">
 <label for="pref">CENTRO DE CUSTO</label>
   <select onchange="onChangeCombo(this)" class="filtro form-control" 
    id="pref" name="pref" dataset="dsAprov" datasetkey="Prefixo" 
    datasetvalue="Prefixo" addBlankLine="true"></select>
</div>

<div class="form-group col-md-2">
 <label for="g2">GESTOR</label>
    <input type="text" class="form-control" id="g1" name="g1">
</div>

js

function onChangeCombo(combo){

    var prefixo = combo.value;

    var c1 = DatasetFactory.createConstraint("Prefixo", prefixo, prefixo, ConstraintType.MUST);
    var constraints - new Array(c1);

    var returnFields - new Array("gestorprincipal");

    var gestor = DatasetFactory.getDataset("dsAprov", returnFields, constraints, null);

    var index = combo.id.substring(combo.id.indexOf('___') + 3);
    var selecionagestor = gestor.values[0]["gestorprincipal"];
    $('#g1').val(selecionagestor)

}

dataset

dataset.addColumn("Prefixo");
dataset.addColumn("gestorprincipal");