I want to change the url of proxy based on a field of my model. Here is a simple definition of a model:

Ext.regModel('MyModel', {

idProperty : 'Id',

fields: [
{ name: 'Id', type: 'string' },
{ name: 'Title', type: 'string' }
],

proxy: {
type : 'rest',
url : '/models/{Id}/relatedrecords' // Id will be variable here.
}
})

Is there a way to do this OOTB?

Thanks in advance.