Unable to get filename while running class in batch mode.

Hi Experts,

I have a class extending from runbase (cannot replace with sysoperation due to internal reasons) .

Facing 2 issues with this class, please suggest a fix 

1. How can i ensure that when use browse to select a file it only shows *.CSV files in the browse window. LINE 23 in below code

2. Code runs without issue when running in non batch mode with Run on property set to "Called from or Client" , however

when running in batch it keep throwing the error "No file selected " even when a file is selected.   LINE97 in below code for same run on properties.

We cannot change the class run on to server as the end users will be browsing & selecting a file from their local system & not server or network share.

Shared below is the code & I have followed this pack /unpack using this MSFT link 

class myClass extends RunBaseBatch
{
    CommaIo                     csvFile;
    Filename                    filename;
    DialogField                 dialogFilename;

    #define.CurrentVersion(2)
    #define.Version1(1)

    #localmacro.CurrentList
        filename
    #endmacro
    #File

protected Object dialog()
{
    DialogRunbase       dialog = super();
    ;
  
    dialogFilename  = dialog.addField(extendedTypeStr(FilenameOpen));
    dialogFilename.value(filename);
    dialog.filenameLookupFilter(["All files", #Allfiles]+#csv]); // HOW TO ENSURE ONLY CSV SHOWS UP

    return dialog;
}

public boolean getFromDialog()
{
     filename  = dialogFilename.value();
     return super();
}

public container pack()
{
    return [#CurrentVersion,#CurrentList];
}

public void run()
{
 

    try
    {
        this.vendUpdate();
    }
    catch (Exception::UpdateConflict)
    {
        throw Exception::UpdateConflict;
    }

}

public boolean unpack(container packedClass)
{
    int version = conPeek(packedClass,1);
    #localmacro.ListV1
     #endmacro
    ;

    switch(version)
    {
        case #CurrentVersion:
            [version,#CurrentList] = packedClass;
            break;

        default:
            return false;
    }

    return true;
 }
 protected void vendUpdate()
{
    TextBuffer               textBuffer   = new TextBuffer();
    SysOperationProgress     importProgress = new SysOperationProgress();
    #AviFiles
    container                dataCon;
    Io                       importFile;
    #file
    str                      Delimiter = ",";
    boolean                  firstRow = true;
    int                      totalNumOfRows,totalnumOfRecordRows;
    int                      counterNumOfRows = 1;
    str                      filePath,fileNameOnly;
    filename                 fileType;
    InteropPermission        permission;
    permission = new InteropPermission(InteropKind::ClrInterop);
    importFile = new CommaTextIo(filename,#IO_Read);

    permission.assert();
    [filePath, fileNameOnly, fileType] = fileNameSplit(filename);

    if((!importFile) || (importFile.status() != IO_Status::Ok))         
       throw error ("No file selected");                               KEEPS throwing this error when running in batch.

    if(fileType != #csv)
        throw error ("Selected filetype is not *.csv");

    if(fileNameOnly != 'UpdateVend')
        throw error ("Selected CSV file is not UpdateVend");

    importFile.inFieldDelimiter(Delimiter);

    try
    {
      while(importFile.status() ==  IO_Status::Ok)
      {
      //main logic
      }
    }
    
    catch
    {
    }

}
}

Thanks

Mav