Synchronization for nested collections

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);
});