Interrupt FuelPHP REST controller flow and display response

I am using FuelPHP's rest controller.

I am trying to break the flow and display my response after encountering an error.

Here is my basic flow needed:

1. When any of the methods are called I run a "validate" function, which validates parameters and other business logic.
2. If the "validate" function determines something is off, I want to stop the entire script and display the errors I have complied so far.

I have tried the following in my "validate" function but it simply exits the validate function... then continues to the initial method being requested. How do I stop the script immediately and display the contents of this response?

return $this->response( array(
        'error_count' => 2,
        'error' => $this->data['errors'] //an array of error messages/codes
    ) );

That is very bad practice. If you exit you not only abort the current controller, but also the rest of the framework flow.

Just validate in the action:

// do your validation, set a response and return if it failed
if ( ! $valid)
{
    $this->response( array(
        'error_count' => 2,
        'error' => $this->data['errors'] //an array of error messages/codes
    ), 400); //400 is an HTTP status code
    return;
}

Or if you want to do central validation (as opposed to in the controller action), use the router() method:

public function router($resource, $arguments)
{
    if ($this->valid_request($resource))
    {
        return parent::router($resource, $arguments);
    }
}

protected function valid_request($resource)
{
    // do your validation here, $resource tells you what was called
    // set $this->response like above if validation failed, and return false
    // if valid, return true
}