MultipartFile.fromBytes(String field, List<int> value, { String filename, MediaType contentType })

Creates a new MultipartFile from a byte array.

contentType currently defaults to application/octet-stream, but in the future may be inferred from filename.

Source 

factory MultipartFile.fromBytes(String field, List<int> value,
    {String filename, MediaType contentType}) {
  ByteStream stream = new ByteStream.fromBytes(value);
  return new MultipartFile(field, stream, value.length,
      filename: filename,
      contentType: contentType);
}