def extract_db_info(self, obj, keys):
        """Extract tags from serialized file"""

        objl = self.convert(obj)

        result = super(DataFrameType, self).extract_db_info(objl, keys)
        ext = self.datamodel.extractor_map['fits']
        if objl:
            with objl.open() as hdulist:
                for field in keys:
                    result[field] = ext.extract(field, hdulist)

                tags = result['tags']
                for field in self.tags_keys:
                    tags[field] = ext.extract(field, hdulist)

                return result
        else:
            return result
Extract tags from serialized file