protected function loadMetaData()
    {
        // Retrieve the transient
        $transientKey = sprintf('WPMVC\Models\Post(%d)::loadMetaData', $this->id());
        $metaData = WP::getTransient($transientKey);
        // If it doesn't exist
        if (!$metaData) {
            $keys = WP::getPostCustom($this->id());
            $metaData = array();
            if ($keys && is_array($keys) && count($keys)) {
                foreach ($keys as $key => $value) {
                    // If only 1 value, it's a string
                    if (is_array($value) && count($value) == 1) {
                        $metaData[$key] = $value[0];
                    } else {
                        $metaData[$key] = $value;
                    }
                }
            }
            WP::setTransient($transientKey, $metaData, static::$transientTimeout);
        }
        $this->metaData = $metaData;
    }