[CLOSED-EXTJSIV-303] Add to Ext.data.Model update/datachanged event

[uzver]

subj

[evant]

We decided not to implement this for 2 reasons:

1) It's not really a common use case to want to listen to an event on a single record, rather you'll want to listen to changes on a group of records.

2) Possible performance implications, records get updated quite a lot, as well as being recreated behind the scenes, which makes it difficult to main the events.

[grnadav]

It's a real usecase for us. No normal workaround either...

[burnnat]

I do have a workaround for this issue - it's not the prettiest solution in the world, but it does work, at least for me. The basic principle is to use Ext.data.Model#join to fool the record into thinking that your listener class is one of the parent stores for the model record, which will then be notified when that particular record is edited. Although the documentation says that Ext.data.Model.join() expects the parameter to be a Store, you don't actually have to extend the Ext.data.Store class. Instead, you just need to be sure to implement "afterEdit", "afterReject", and "afterCommit" methods on your listener class, and they will be called appropriately by the record. Just be sure to unjoin() when you're done with the listener!

Here's a simple example:

Ext.define('User', {
    extend: 'Ext.data.Model',
    fields: ['id', 'name']
});

Ext.define('Listener', {
    constructor: function(record) {
        record.join(this);
    },
    
    afterEdit: function(record) {
        console.log('edit');
    },
    
    afterReject: function(record) {
        console.log('reject');
    },
    
    afterCommit: function(record) {
        console.log('commit');
    }
});

var user = Ext.create('User', {
    id: 1,
    name: 'John'
});

var listener = Ext.create('Listener', user);

user.set('name', 'Joe');

Note that I'm using this with ExtJS 4.1.0 ... I don't know if it will work on other versions or not.

[skyboyer]

Maybe it make sense to add configuration item for making model observable?
So if it is needed model will have events