Backbone.js sync event in collection

Question

According to doc here: http://documentcloud.github.com/backbone/#FAQ-events collection has sync event fired when i do something to sync collection with server. I try to invoke fetch method on collection and wait for sync event on it, but it never happens. Add event is fired, but I need only one event after syncing all items in collection to update corresponding view. There is another way to get this event fired?

Answer 1

The solution is to fire up sync event maunually in 'success' callback passed as param to fetch method.

this.collection.fetch({add: true, success: function(collection, response){
            collection.trigger('sync');
}});

Answer 2

I believe the "sync" event is only fired when you change a model. So if you create, update or delete a model, then the "sync" event will fire.

In your case, I think you want to listen for the "reset" event on the collection.

Edit: If you're setting the {add:true} option, then there is no single Backbone event that will fire after all the models have been added. You have a few options:

1. Just listen to the add event and expect it be called repeatedly
2. Emulate a single event by using a handler that has been debounced using the _.debounce() function.

3. The return value from fetch() is a jQuery XMLHttpRequest object. It implements the jQuery Deferred interface. So you could listen for that finish. For example:

   myCollection.fetch({add:true}).done(function(){
       myView.render(); //or whatever
   });