Problem filtering counties by the district selected with ng-change in Angularjs?

Question

I have a mobile app where I have two select option (districts and counties). What I intend is that when choosing a district appear only the counties that belong to that district.

How can I do that? I’ve tried filtering through ng-change only that it is not appearing the name of the councils appears the blank list and by the console I can verify that filters.

View

<div ng-controller="FiltraEstabelecimentos">
        <form ng-submit>
            <div class="row">
                <div class="col">
                    <label ng-controller="ListaDistritos" style="border-radius: 10px; margin: 0px 0px 10px 0px;" class="item item-input item-select">
                        <div class="input-label">
                            Distrito
                        </div>
                        <select ng-controller="ListaConcelhos" ng-model="distrito" ng-options="lista_distritos as lista_distritos.titulo for lista_distritos in distritos" ng-change="id_distrito()"></select>
                    </label>
                    <label ng-controller="ListaConcelhos" style="border-radius: 10px;" class="item item-input item-select">
                        <div class="input-label">
                            Concelho
                        </div>
                        <select ng-model="concelho" ng-options="lista_concelhos as lista_concelhos.titulo for lista_concelhos in concelhos"></select>
                    </label>
                </div>
            </div>
            <div style="margin:0px 10px 0px 10px;">
                <button type="submit" ng-click="filtra_estabelecimentos(input)" style="background-color: #CA5B60; border:#CA5B60; border-radius: 10px;" class="button button-block button-positive">
                    <i class="ion-search"></i> Pesquisar
                </button>
            </div>
        </form>  
    </div> 

PHP districts

function converte($term, $tp) {
    if ($tp == "1") $palavra = strtr(ucwords(strtoupper($term)),"àáâãäåæçèéêëìíîïðñòóôõö÷øùüúþÿ","ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ×ØÙÜÚÞß");
    elseif ($tp == "0") $palavra = strtr(ucwords(strtolower($term)),"ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ×ØÙÜÚÞß","àáâãäåæçèéêëìíîïðñòóôõö÷øùüúþÿ");
    return $palavra;
}

$distritos = array();

$sql = $conexao->prepare("SELECT * FROM distritos ORDER BY titulo");
$sql->execute();
$distritos = $sql->fetchAll(PDO::FETCH_ASSOC);

foreach ($distritos as $rows ) {
    $distritos[] = array(
        'titulo'        => converte($rows['titulo'], 0),
    );
}
echo json_encode($distritos);

PHP Concelhos

 function converte($term, $tp) {
    if ($tp == "1") $palavra = strtr(ucwords(strtoupper($term)),"àáâãäåæçèéêëìíîïðñòóôõö÷øùüúþÿ","ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ×ØÙÜÚÞß");
    elseif ($tp == "0") $palavra = strtr(ucwords(strtolower($term)),"ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ×ØÙÜÚÞß","àáâãäåæçèéêëìíîïðñòóôõö÷øùüúþÿ");
    return $palavra;
}

$concelhos = array();

$sql = $conexao->prepare("SELECT * FROM concelhos WHERE id_mae = :distritos ORDER BY titulo");
$sql->bindParam(':distritos', $_GET['id_distrito'], PDO::PARAM_INT); 
$sql->execute();
$row = $sql->fetchAll(PDO::FETCH_ASSOC);

foreach ($row as $rows ) {
    $concelhos[] = array(
        'titulo'        => converte($rows['titulo'], 0),
    );
}
echo json_encode($concelhos);

County and District Controller

.controller('ListaDistritos', function($scope, $http) {
    $http.get("https://www.sabeonde.pt/api/api_distritos.php").success(function (data) {
        $scope.distritos = data;
    });
})
.controller('ListaConcelhos', function($scope, $http, $stateParams) {
    $scope.id_distrito= function (){
        $http.get("https://www.sabeonde.pt/api/api_concelhos.php?id_distrito="+$scope.distrito.id).success(function (data) {
            $scope.concelhos = push(data);
        });
    };
})

Answer 1

To list the counties according to the district selected, it is necessary to add a WHERE to specify this.

$sql = $conexao->prepare("SELECT * FROM concelhos 
                          WHERE id_distrito = :distritos ORDER BY titulo");

$sql->bindParam(':distritos', $distritos, PDO::PARAM_INT); ;