Extracts the data from the representation submitted in the request
        body and returns it.

        This default implementation uses a representer for the content type
        specified by the request to perform the extraction and returns an
        object implementing the
        :class:`everest.representers.interfaces.IResourceDataElement`
        interface.

        :raises HTTPError: To indicate problems with the request data
          extraction in terms of HTTP codes.

def _extract_request_data(self):
        """
        Extracts the data from the representation submitted in the request
        body and returns it.

        This default implementation uses a representer for the content type
        specified by the request to perform the extraction and returns an
        object implementing the
        :class:`everest.representers.interfaces.IResourceDataElement`
        interface.

        :raises HTTPError: To indicate problems with the request data
          extraction in terms of HTTP codes.
        """
        rpr = self._get_request_representer()
        return rpr.data_from_bytes(self.request.body)