Google Maps API with backbone, how to bind an event - google-maps-api-3

Question

I've seen several other posts about this, but the answers from those responses don't work for me.
The other responses:
How do I bind a google maps geocoder.geocode() callback function
Backbone.js with Google Maps - problems with this and listeners
My code:
var ns = namespace('camelcase.geomanager.map');
ns.Site = Backbone.Model.extend({
url: '/site'
});
ns.Sites = Backbone.Collection.extend({
model: ns.Site
});
ns.MapView = Backbone.View.extend({
initialize: function() {
this.markers = new Array();
// Create the Google Map
var mapOptions = {
center: new google.maps.LatLng(-34.397, 150.644),
zoom: 8,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
this.googleMap = new google.maps.Map(this.$(".mapCanvas")[0], mapOptions);
// Register events
this.collection.on('add', this.addSite, this);
this.collection.on('remove', this.removeSite, this);
},
addSite: function(model) {
// Get model attributes
var elementId = model.get('elementId');
var latitude = model.get('latitude');
var longitude = model.get('longitude');
var id = model.get('id');
var notes = model.get('notes');
var title = ""+id;
// Create icon and marker
var icon = '/resources/img/elements/' + elementId + '_marker.png';
var latLng = new google.maps.LatLng(latitude, longitude);
var marker = new google.maps.Marker({
position: latLng,
title: title,
map: this.googleMap,
icon: icon
});
// Load info window
var siteBubbleTemplate = _.template($('#siteBubbleTemplate').html());
var siteContent = $(siteBubbleTemplate({
siteId: id,
siteNotes: notes
}))[0];
var infoWindow = new google.maps.InfoWindow({
content: siteContent
});
// Show info window when clicking on marker
_.bindAll(this, this.openSite);
google.maps.event.addListener(marker, 'click', this.openSite(id));
this.markers.push({
id: id,
marker: marker,
infoWindow: infoWindow
});
},
openSite: function(id) {
var marker;
for (var c=0; c<this.markers.length; c++) {
marker = this.markers[c];
// Open the appropriate marker info window
if (marker.id == id) {
marker.infoWindow.open(googleMap, marker.marker);
}
// Close the rest
else {
marker.infoWindow.close();
}
}
}
});
The offending line:
google.maps.event.addListener(marker, 'click', this.openSite(id));
The error being reported in firebug:
TypeError: func is undefined
underscore.js (line 482)

Answer 1

I suspect this.marker is the problem, since you should be able to just refer to it by name.
google.maps.event.addListener(marker, 'click', this.openSite(id));

Answer 2

Looks like it was a scoping issue. I solved my problem with the following code:
// Show info window when clicking on marker
_.bindAll(this);
var _self = this;
var doSomething = function(event) {
_self.openSite({
event: event
});
};
google.maps.event.addListener(marker, 'click', doSomething);
I'll give the answer to whoever can best explain why this works.

Answer 3

In a model/collection event handler, Backbone sets 'this' to the model/collection which raised the event. If you call _.bindAll(this) in your view's initialize(), 'this' will be set to the view in your event handlers. Check out this jsfiddle: http://jsfiddle.net/9cvVv/339/ and see what happens when you uncomment _.bindAll(this);
var MyView = Backbone.View.extend({
initialize: function() {
// TODO: uncomment this line
// _.bindAll(this);
this.collection.bind('myEvent', this.onDoSomething);
},
updateCollection: function() {
this.collection.doSomething();
},
onDoSomething: function() {
if (this.models && typeof this.models.length === 'number') {
alert('"this" is a collection.');
}
else if (this.collection) {
alert('"this" is the view.');
}
else {
alert('"this" is something else.');
}
}
});