HandleMemoryFile.cs

public const string SessionKey = "MyFileImportSessionKey";
		
public PXAction<GLTran> UploadFileBatch;
[PXUIField(DisplayName = "Upload File as Batches", MapEnableRights = PXCacheRights.Select, MapViewRights = PXCacheRights.Select, Visible = true)]
[PXButton()]
public virtual IEnumerable uploadFileBatch(PXAdapter adapter)
{
	//Ask user to upload file, continue if it is OK
	if (this.NewFilePanel.AskExt() == WebDialogResult.OK)
	{
		//Retreaving file from session by key
		PX.SM.FileInfo info = PXContext.SessionTyped<PXSessionStatePXData>().FileInfo[SessionKey] as PX.SM.FileInfo;
		//Binary data will be inside FileInfo
		Byte[] bytes = info.BinData;

		//Removing file from session to save memory
		System.Web.HttpContext.Current.Session.Remove(SessionKey);
	}

	return adapter.Get();
}