Synchronization for nested collections - backbone.js

Question

Suppose I have models:
var Book = Backbone.Model.extend({
// ...
});
var Store = Backbone.Model.extend({
getBooks: function(){
this.books = new Books(App.Singletons.AllBooks.where({storeId: this.id}));
return this.books;
}
});
Store has many books.
Also suppose I have a collection:
var Books = Backbone.Collection.extend({
model: Book
});
In a complex business logic I need a base store object for the Books:
var App = App || {};
App.Singletons = App.Singletons || {};
var books = new Books();
books.fetch();
App.Singletons.AllBooks = books;
// ...
What the best way for syncing a singleton model for operations like this:
var store = new Store({id: 1});
store.fetch();
store.getBooks();
store.books.add(...);
store.books.remove(...);
// etc
// There I need to sync with App.Singletons.AllBooks
Now I'm overriding these methods in the Books collections. And there the App.Singletons.AllBooks is being synced.
I think there should be another better solution for this task.
Thanks for helping.

Answer 1

If you want to keep something in "sync", override the sync method.
In the case of store:
var Store = Backbone.Model.extend({
getBooks: function() {
this.books = new Books(App.Singletons.AllBooks.where({
storeId: this.id
}));
return this.books;
},
sync: function(method, model, options) {
switch (method) {
case 'create':
//your logic to sync with App.Singletons.AllBooks
break;
case 'read':
//your logic to sync with App.Singletons.AllBooks
break;
case 'update':
//your logic to sync with App.Singletons.AllBooks
break;
case 'delete':
//your logic to sync with App.Singletons.AllBooks
break;
}
}
Backbone.prototype.sync.call(this, method, method, options);
});