Backbone dualStorage Adapter v0.1

This plugin is extension of original plugin Backbone dualStorage (https://github.com/lucian1900/Backbone.dualStorage). Extension includes:

• differential fetch from server (Allow to fetch only changes happened to actual model), meaning it updates local cache of data based on server changes.

This Plugin should be used for making application work offline, and sync all data with server (client changes and server changes as well), whenever gets connection and try to synchronize.

A dualStorage adapter for Backbone. It's a drop-in replacement for Backbone.Sync() to handle saving to a localStorage database as a cache for the remote models. It is extended for fetching only changes (not full fetch) from server.

Usage

Include Backbone.dualStorage after having included Backbone.js:

<script type="text/javascript" src="backbone.js"></script>
<script type="text/javascript" src="backbone.dualstorage.js"></script>

Create your models the usual way. Use DualStorageCollection for making your Collection backed by localStorage (This is a variation from original implementation) window.TodoList = Backbone.DualStorageCollection.extend({ model: Todo, localStorage: new Store("todos"), url : "http://localhost:3000/todos", lastUpdatedTimestampAttr:"lastUpdated", // Should be time in standard date.toJSON() format, Identifies model last updated time. deletedIdAttr:"deleted", //should be boolean, Identifies entries deleted by server. Server should send 'deleted:true' attribute in deleted model. ... ... ...

For fetching only local changes use remote:false
Todos.fetch({remote:false});

You can also deactivate dualsync to some requests, when you want to sync with the server only later. Todos.create({name: "someone"}, {remote: false});

Data synchronization

When the client goes offline, dualStorage allows you to keep changing and destroying records. All changes will be send when the client goes online again.

// server online. Go!
Todos.load();       // if first-time loading, load all Todos models from server and save them into localstorage, 
					//after first-time it will only load changes and updates localstorage.

// server offline!
Todos.create({name: "Turing"});   // you still can create new Todo...
Todos.models[0].save({order: 21});  // update existing ones...
Todos.models[1].destroy();        // and destroy as well

// server online again!
Todos.syncDirtyAndDestroyed();    // all changes are sent to the server and localStorage is updated

Keep in mind that if you try to fetch() a collection that has dirty data, only data currently in the localStorage will be loaded. collection.syncDirtyAndDestroyed() needs to be executed before trying to download new data from the server.

Use Todos.load(); for fetching server changes and update local cache with it. You can still use Todos.fetch() for reloading all data from server.

Credits

Thanks to Mark Woodall for the QUnit tests. Thanks to Jerome Gravel-Niquet for Backbone.dualStorage