async def json(self, *, encoding: Optional[str] = None) -> Optional[Dict[str, Any]]:
        """Like read(), but assumes that body parts contains JSON data."""
        data = await self.read(decode=True)
        if not data:
            return None
        encoding = encoding or self.get_charset(default="utf-8")
        return cast(Dict[str, Any], json.loads(data.decode(encoding)))
Like read(), but assumes that body parts contains JSON data.
lib/aiohttp/multipart.py