Ember data entity id generation - ember.js

Question

When new model is created and saved with RESTAdapter its Id property is undefined, because my backend is responsible for id generation. So when I return to grid there is 2 same entities: first - with empty Id (from RESTAdapter cache, I think) and second - with correct Id returned from backend.
Any ideas? Maybe it is posiible to disable RESTAdapter cache?
UPDATE
My code for entity creation.
submit:function () {
var manager = App.store.createRecord(App.Manager, {
firstName:this.get('firstName'),
lastName:this.get('lastName'),
speciality:this.get('speciality')
});
App.store.commit();
this.get('controller').transitionTo('managers');
return false;
}
NEW UPDATE
Thanks to Mike Grassotti hints. Here some details for my issue.
One antity have Id, another have no Id.
If I remove App.store.commit() code, there is no POST to server and only entity without Id will be displayed.
This entity has isLoaded=false and isError=true.

Answer 1

When new model is created and saved with RESTAdapter its Id property is undefined, because my backend is responsible for id generation.
Right, but there is nothing unusual about this - ember expects id generation to be done by the backend.
So when I return to grid there is 2 same entities: first - with empty Id (from RESTAdapter cache, I think) and second - with correct Id returned from backend.
OK. What do you mean by same 2 entities - surely they are different js objects. Try logging each of them to console like this:
console.log(entityOne.toString());
console.log(entityTwo.toString());
Any ideas?
There are many things that could cause this to happen. Sounds like somehow you are creating two new records and saving just one of them. Or could be the API response does not match what ember expects, causing an extra record to get created.
Try to enable logging on your records, then watch console so you can see what's going on as your model is saved. Hopefully this will give you some insight into when/how the extra record is being created.
record.set("stateManager.enableLogging", true)
Inspect browser communication with your api and compare JSON to see if it matches what the ember rest adapter expects.
Post that JSON and the rest of your source code (model definition, etc.) to Stack Overflow, maybe a second set of eyes will help.
Check this post for some other debugging tips: http://www.akshay.cc/blog/2013-02-22-debugging-ember-js-and-ember-data.html
Maybe it is posiible to disable RESTAdapter cache?
RESTAdapter does not maintain a separate cache of model objects. And since you are not trying to do anything special, there should be no need to take a step like that.

Answer 2

Many thanks to Mike Grassotti, I have found an answer to my question.
The good question was
With App.store.commit() back in, what does the JSON response from
server look like?
+1 for that comment.
I can't find any info in ember-data documentation for that, so some links still would be helpful for me. I change the result returned from backend and everything works fine now.
{
"manager": {
"firstName": "test",
"lastName": "test",
"speciality": "test",
"id": "acd325ac-03eb-419e-be8a-d4ac42e8c235"
}
}