def process_on_store(self, obj, byte_stream):
pass<EOL>
Override this method to make customised updates to the object
        when a file is going to be stored.

        This may be used to parse file content and extract values for
        additional fields.

        Note: as populate_obj() on form fields my be called in an arbitrary
        order, do not assume that other fields in obj have been correctly set.
        If an extra information (from other fields) is necessary for parsing
        the supplied file content, a form-field validator may be used to copy
        it directly from the form to this field.

        :param obj: model object
        :param byte_stream: file contents