使用 gmaps4rails 获取标记信息窗口

Get marker infowindow using gmaps4rails

我正在使用 Rails 4 和 gem gmaps4rails。我怎样才能在js中得到marker.infowindow? 这是我的代码:

handler = Gmaps.build('Google');
handler.buildMap({ provider: {scrollwheel: false}, internal: {id: 'event-detail-map'}}, function(){
  markers = handler.addMarkers([
      {
          "lat": "<%= @event.location.latitude %>",
          "lng": "<%= @event.location.longitude %>",
          "infowindow": 'Hello!'
      }  
  ]);
  marker = markers[0];
  marker.getServiceObject().addListener('mouseover', function () {
      marker.infowindow.open(marker.serviceObject.map,   marker.serviceObject);
  });

  handler.bounds.extendWith(markers);
  center = {lat: <%= @event.location.latitude %>, lng: <%=@event.location.longitude %>};

  handler.map.centerOn(center);
  handler.getMap().setZoom(12);
});

控制台给我写了这个:

Uncaught TypeError: Cannot read property 'open' of undefined

而不是 marker.infowindow.open 使用 marker.infowindow.render_to_string 参考这个 link (https://github.com/apneadiving/Google-Maps-for-Rails/wiki/Controller)