How to commit a record modification?

app.Ajax.request({

  url    : 'db/Contacts',

  method : 'POST',

  params : record.getData(),

  scope  : this,

  success: function(response){

      if(response.success){

          record.id = response.id;

          var store = this.getDataview().getStore();

          store.add(record);

          store.commitChanges();

      }

  }

});