listView.filters([
    nga.field('q')
        .label('')
        .pinned(true)
        .template('<div class="input-group"><input type="text" ng-model="value" placeholder="Search" class="form-control"></input><span class="input-group-addon"><i class="glyphicon glyphicon-search"></i></span></div>')
        .transform(v => v && v.toUpperCase()) // transform the entered value before sending it as a query parameter
        .map(v => v && v.toLowerCase()), // map the query parameter to a displayed value in the filter form
])