extracts from an item only fields that we want to output as extracted information
        :rtype: object
        :param item:
        :return:

def extract_relevant_info(item):
        """
        extracts from an item only fields that we want to output as extracted information
        :rtype: object
        :param item:
        :return:
        """
        article = {
            'authors': item['article_author'],
            'date_download': item['download_date'],
            'date_modify': item['modified_date'],
            'date_publish': item['article_publish_date'],
            'description': item['article_description'],
            'filename': item['filename'],
            'image_url': item['article_image'],
            'language': item['article_language'],
            'localpath': item['local_path'],
            'title': item['article_title'],
            'title_page': ExtractedInformationStorage.ensure_str(item['html_title']),
            'title_rss': ExtractedInformationStorage.ensure_str(item['rss_title']),
            'source_domain': ExtractedInformationStorage.ensure_str(item['source_domain']),
            'text': item['article_text'],
            'url': item['url']
        }

        # clean values
        for key in article:
            value = article[key]
            if isinstance(value, str) and not value:
                article[key] = None

        return article