private function loadFilterValues()
    {
        $session = new Session();
        $this->filterValues = $session->get($this->getStorageNamespace());
        // Because entities saved into the session are not currently managed,
        // we retrieve the reference id previously set by the storeFilterValues function
        // to load the expected entity
        foreach($this->filters as $datagridFilter) {
            if ($datagridFilter->getType() instanceof DatagridFilterTypeEntity) {
                if (!empty($this->filterValues[$datagridFilter->getName()])) {
                    $filterOptions = $datagridFilter->getOptions();
                    $this->filterValues[$datagridFilter->getName()] = $this->entityManager->getReference(
                        $filterOptions['class'],
                        $this->filterValues[$datagridFilter->getName()]
                    );
                }
            }
        }
    }