Empty Data

[DieterGribnitz]

I also got the issue with the component not returning any data.

On line 306 in the RestComponent the code looks like this:
if (false === ($extract = @$this->settings['actions'][$this->Controller->action]['extract'])) {

To fix the issue replace it with:
if (false === ($extract = @$this->settings['actions']['extract'][$this->Controller->action])) {

There are notices also coming up in new versions of cake.
(Could be )
All functions that use $controller should be referenced as follows:
beforeRender (Controller $Controller) {
instead of
beforeRender (&$Controller) {