Model Sync Local Storage - sync layer for Model and ModelList

[clarle]

Looks like I'm probably too late for this release, but here goes:

This provides Y.ModelSync.Local, an extension which provides a sync implementation through locally stored
key value pairs, either through the HTML localStorage API or falling back onto an in-memory cache, that can be mixed into a Model or ModelList subclass.

A group of Models/ModelLists is serialized in localStorage by either its class name, or a specified 'root' that is provided.

Example Usage

var User = Y.Base.create('user', Y.Model, [Y.ModelSync.Local], {
    root: 'users'
});

var Users = Y.Base.create('users', Y.ModelList, [Y.ModelSync.Local], {
    model: User,
    root  : 'users'
});

var myUser = new User({id: '123'});

// Will load the data from the in-memory object
// or HTML5 localStorage
myUser.load(); 

// Will update the in-memory object 
// and HTML5 localStorage
myUser.set('name', 'Eric F').save();

// Will delete the item in the in-memory object 
// and HTML5 localStorage
myUser.destroy({remove: true});

// Will create a new item in the in-memory object 
// and localStorage under key 'users' with a generated GUID
var newUser = new User({name: 'Clarence L'});
newUser.save(); 

To-do

Has API docs, high test coverage, and is only missing user documentation. However, there is an example writen for TodoMVC that can be found here:

https://github.com/clarle/todomvc/tree/yui-3.6.0/architecture-examples/yuilibrary

[ericf]

(Keeping a record of what we decided in IRC)

@clarle Looks good on first glance! But let's keep iterating on this in Gallery and put it through its paces some more. We'll plan on merging this in for 3.7.0pr1.

[ericf]

We don't have to explicitly require model-list. I left it out of ModelSync.REST's requirements too.

[juandopazo]

Looks great!

[clarle]

@juandopazo and anyone else interested in testing it out, ModelSync.Local is available in the Gallery here:

http://yuilibrary.com/gallery/show/model-sync-local

[juandopazo]

I'm totally using this for a new project :)

[juandopazo]

How do you propose to use the extension? Like this?

var exts = [];
if (Y.config.win.localStorage) {
  exts.push(Y.ModelSync.Local);
}
var Foo = Y.Base.create('foo', Y.Model, exts)?

[clarle]

It should fall back to an in-memory store if Y.config.win.localStorage is not available.

[juandopazo]

Does it make sense to use Y.CacheOffline?

[clarle]

@ericf and I discussed this before, and we decided that Y.CacheOffline had too much overhead and not all of the parts in it would be needed for ModelSync.Local, so just a quick re-implementation of the core portion of it would be fine. Any thoughts on your side?

[juandopazo]

Nope, I was thinking exactly the same. Let me know if I you need help with the implementation.

[ericf]

A quick update:

I am going to need to wait until after this sprint to pull this in (code freeze is this Friday, 9/7).

That said, I've been thinking about using localStorage in conjunction with ModelSync.REST, which could enable a couple of things:

1. Offline support: This seem great for mobile devices which may have a spotty connection. This is probably a huge rabbit hole, since master-master replication is a PITA and app-specific.
2. Multi-tab support: One thing I really hate is having an app open in two tabs and each one displaying a different state. By passing all changes through localStorage, the sync layer can listen to the storage event and to get updates which are happening in other tabs/windows of that browser.

[juandopazo]

\o/ Thanks for tackling my problems!

[clarle]

Yeah, I understand, it's for the better. I've made some changes to the Gallery version of LocalStorage that I haven't synced up to this PR yet, my apologies.

I still need to do more testing on it myself in the meantime and write user documentation for it. There might be a fairly major API change for this module (I forgot about the use case where people can have multiple ModelLists that share the same Model), so that's one thing I need to work on.

[triptych]

@clarle would it make sense to close this one out in favor of your new one #385 ?

[clarle]

@triptych Yep, sounds good to me.