function filter_district(city_el){
    var obj = city_el;
    var form = obj.form;
    if (!form)
        return;
    var target = form.elements['id_district'];
    var sel = target.value;
    $.post('/reference/get_districts_ajax/',
        {'city_id': obj.value},
        function(json){
            eval("var data = " + json);
            if (data){
                for(var count = target.options.length - 1; count >= 0; count--){
                    target.options[count] = null;
                }
                for (var i = 0; i < data['districts'].length; i++){
                    if (data['districts'][i][1] == sel)
                        target.options.add(new Option('' + data['districts'][i][0], '' + data['districts'][i][1], true));
                    else
                        target.options.add(new Option('' + data['districts'][i][0], '' + data['districts'][i][1]));
                }
                if (typeof(RecreateSelect) != 'undefined') RecreateSelect('id_district', data['districts']);
            }
        });
}


function filter_metro(city_el){
    var obj = city_el;
    var form = obj.form;
    if (!form)
        return;
    var target = form.elements['id_metro'];
    var sel = target.value;
    $.post('/reference/get_metro_ajax/',
        {'city_id': obj.value},
        function(json){
            eval("var data = " + json);
            if (data){
                for(var count = target.options.length - 1; count >= 0; count--){
                    target.options[count] = null;
                }
                for (var i = 0; i < data['metro'].length; i++){
                    if (data['metro'][i][1] == sel)
                        target.options.add(new Option('' + data['metro'][i][0], '' + data['metro'][i][1], true));
                    else
                        target.options.add(new Option('' + data['metro'][i][0], '' + data['metro'][i][1]));
                }
                if (typeof(RecreateSelect) != 'undefined') RecreateSelect('id_metro', data['metro']);
            }
        });
}