save store with hasmany and belong to relationship - ember.js

Question

I have a store with "row" and "column" models (tr and td in the html), buttons add rows and columns into rows.
I want to save the changes to server only when a "save" button is pressed.
At this time have done this code, it nearly work, but I have some problem with the "save" method :
The "id" of row and columns came from server when they are saved, but when a row is saved it don't know allready the columns id, and visversa. So that the save method is buggy and the code not nice at all.
I beggin with Ember, certainly there is a better way to do that ?, thank you if you can give me some help.
May be also something could be better done in my addRow and addColumn methods ?
Ember 1.11 with restAdapter
App.IndexRoute = Ember.Route.extend({
model: function () {
return this.store.find('row');
},
setupController: function(controller, model) {
controller.set('model', model);
}
});
App.Row = DS.Model.extend({
titre: DS.attr('string'),
columns: DS.hasMany('column', {async: true, embedded: 'always'}),
});
App.Column = DS.Model.extend({
titre: DS.attr('string'),
row: DS.belongsTo('row', {async: true}),
});
App.RowSerializer = DS.RESTSerializer.extend({
serializeHasMany: function(record, json, relationship) {
var hasManyRecords, key;
key = relationship.key;
hasManyRecords = Ember.get(record, key);
if (hasManyRecords && relationship.options.embedded === "always") {
json[key] = [];
hasManyRecords.forEach(function(item, index) {
json[key].push(item.get('id'));
});
}else{
this._super(record, json, relationship);
}
}
});
App.IndexController = Ember.Controller.extend({
selectedColumn: null,
actions: {
save: function(){
var row = this.store.all('row');
row.forEach(function(r, index, self){
r.save().then(function(r2){
r2.get('columns').forEach(function(c){
c.set('row',r2);
c.save().then(function(){
r.save();
})
})
})
})
},
clickCol: function(column){
this.set('selectedColumn', column)
},
addRow: function(){
_this = this;
var newRow = _this.store.createRecord('row',{titre:'Titre row'});
var newColumn = _this.store.createRecord('column', {
titre: 'Titre colonne',
})
newRow.get('columns').addObject(newColumn);
},
addColumn: function(){
_this = this;
this.get('selectedColumn').get('row').then(function(r){
var newColumn = _this.store.createRecord('column', {
titre: 'Titre colonne',
row: r
})
})
}
}
})
EDIT
I did find this :
DS.RESTAdapter: Robust Support for Parent->Child Hierarchies
where there is among other writted : "Allow parent and child records to be saved in the same commit", "[RESTAdapter] Allow new parent, child to be saved at once"...
witch seems to be something like I'm looking for, but can't find anywhere how to make it work ?
also this :
Client-Side IDs with Ember Data
witch say "Consider the case where the user creates a post with several attachments. You’ll need to make sure that the post is saved and has its ID resolved before attempting to save the child models in order to preserve this relationship"...