gmaps4rails - Drop a marker and update fields attribute in a form - ruby-on-rails-3

Question

I'm trying to implement this, from the gem wiki https://github.com/apneadiving/Google-Maps-for-Rails/wiki/Javascript-goodies
<% content_for :scripts do %>
<script type="text/javascript" charset="utf-8">
var markersArray = [];
// On click, clear markers, place a new one, update coordinates in the form
Gmaps.map.callback = function() {
google.maps.event.addListener(Gmaps.map.map, 'click', function(event) {
clearOverlays();
placeMarker(event.latLng);
updateFormLocation(event.latLng);
});
};
// Update form attributes with given coordinates
function updateFormLocation(latLng) {
$('location_attributes_latitude').value = latLng.lat();
$('location_attributes_longitude').value = latLng.lng();
$('location_attributes_gmaps_zoom').value = Gmaps.map.map.getZoom();
}
// Add a marker with an open infowindow
function placeMarker(latLng) {
var marker = new google.maps.Marker({
position: latLng,
map: Gmaps.map.map,
draggable: true
});
markersArray.push(marker);
// Set and open infowindow
var infowindow = new google.maps.InfoWindow({
content: '<div class="popup"><h2>Awesome!</h2><p>Drag me and adjust the zoom level.</p>'
});
infowindow.open(Gmaps.map.map,marker);
// Listen to drag & drop
google.maps.event.addListener(marker, 'dragend', function() {
updateFormLocation(this.getPosition());
});
}
// Removes the overlays from the map
function clearOverlays() {
if (markersArray) {
for (var i = 0; i < markersArray.length; i++ ) {
markersArray[i].setMap(null);
}
}
markersArray.length = 0;
}
</script>
<% end %>
But with no luck...I'm guessing its more of an issue with the name/id of my field(s), pardon my javascript knowledge.
I've changed the fields to update with the coordinates:
function updateFormLocation(latLng) {
$('location[lat]').value = latLng.lat();
...
}
But the field doesn't get updated:
= simple_form_for :location do |l|
= l.input :lat
...
Am I missing something? Thanks!

Answer 1

By the look of it, that syntax is written for prototype. If you're using rails 3.1 with jQuery, you'll need to update that syntax to find your DOM nodes.
i.e. if you're looking for an element with id "location_attributes_latitude", you need to use:
$('#location_attributes_latitude')
And in order to set the value:
$('#location_attributes_latitude').val(latLng.lat());

Answer 2

If you only need to drop an update exist marker, just only need to do this
location_gmaps = () ->
Gmaps.map.callback = () ->
google.maps.event.addListener Gmaps.map.markers[0].serviceObject, 'dragend', (event) ->
updateFormLocationEventos(event.latLng)
# Update form attributes with given coordinates
updateFormLocationEventos = (point) ->
$('#event_position_latitude').val(point.lat())
$('#event_position_longuitude').val(point.lng())
I hope this help you