HTMLapplication/x-www-form-urlencoded (mặc định, encode key=value). multipart/form-data (bắt buộc khi upload file). text/plain (không encode, dùng cho debug).
Upload file phải dùng multipart.
application/x-www-form-urlencoded (default, encodes key=value pairs). multipart/form-data (required for file uploads). text/plain (no encoding, for debugging only).
File uploads must use multipart.