Measurement::attach PHP Method

    public function attach($entity, $origin = false)
    {
        $ref = new MeasurementReference();
        $ref->patient_measurement_id = $this->getPatientMeasurement()->id;
        $ref->origin = $origin;
        if ($entity instanceof Episode) {
            $ref->episode_id = $entity->id;
        } elseif ($entity instanceof Event) {
            $ref->event_id = $entity->id;
        } else {
            throw new Exception("Can only attach measurements to Episodes or Events, was passed an object of type " . get_class($entity));
        }
        $ref->save();
        return $ref;
    }