How to access complex REST resources with ExtJS 5 - rest

Question

I am using ExtJS 5 and I want to access complex REST resources as discussed in this similar thread using ExtJS 4.
The REST service that I am accessing exposes these resources:
GET /rest/clients - it returns a list of clients
GET /rest/users - it returns a list of all users
GET /rest/clients/{clientId}/users - it returns a list of users from the specified client.
I have these models:
Ext.define('App.model.Base', {
extend: 'Ext.data.Model',
schema: {
namespace: 'App.model'
}
});
Ext.define('App.model.Client', {
extend: 'App.model.Base',
fields: [{
name: 'name',
type: 'string'
}],
proxy: {
url: 'rest/clients',
type: 'rest'
}
});
Ext.define('App.model.User', {
extend: 'App.model.Base',
fields: [{
name: 'name',
type: 'string'
},{
name: 'clientId',
reference: 'Client'
}],
proxy: {
url: 'rest/users',
type: 'rest'
}
});
I did this:
var client = App.model.Client.load(2);
var users = client.users().load();
And it sent, respectively:
//GET rest/clients/2
//GET rest/users?filter:[{"property":"personId","value":"Person-1","exactMatch":true}]
Questions:
Is there any way that I can send my request to "GET rest/clients/2/users" without updating the user proxy url manually with its clientId?
How can I send above request without losing the original url defined in App.model.User, "rest/users"

Answer 1

I think this essentially the same as this question:
Accessing complex REST resources with Ext JS
I don't think much has changed since it was first asked.