Detects the uploaded file name. First searches a 'filename' url kwarg.
        Then tries to parse Content-Disposition header.

def get_filename(self, stream, media_type, parser_context):
        """
        Detects the uploaded file name. First searches a 'filename' url kwarg.
        Then tries to parse Content-Disposition header.
        """
        try:
            return parser_context['kwargs']['filename']
        except KeyError:
            pass

        try:
            meta = parser_context['request'].META
            disposition = parse_header(meta['HTTP_CONTENT_DISPOSITION'].encode('utf-8'))
            filename_parm = disposition[1]
            if 'filename*' in filename_parm:
                return self.get_encoded_filename(filename_parm)
            return force_text(filename_parm['filename'])
        except (AttributeError, KeyError, ValueError):
            pass