public function toArray()
    {
        $schema = array(
            'name' => $this->_name,
            'label' => $this->_label,
            'description' => $this->_description,
            'type' => $this->_type,
            'store' => $this->_isStored,
            'index' => $this->_isIndexd,
            'multivalue' => $this->_isMultiValued,
        );

        if (isset($this->_size)) {
            $schema['size'] = $this->_size;
        }

        return $schema;
    }