Dump DYNPRO_MSG_IN_HELP on F4 help for file selection

While processing the “F4” of the file selection using cl_gui_frontend_services=>file_open_dialog, if the user selects nothing and chooses the cancel button, we always want to give a message at this time.

Please don’t try to output an “E” message at your program; otherwise, it will trigger the dump error ‘DYNPRO_MSG_IN_HELP’ with the category ‘Error at Screen Runtime’. Instead of the Error message, just change to the ‘S’ type will do and stop further processing.

Take this as a template backup for file selection : )

CONSTANTS: 
      c_win_title TYPE string VALUE 'Open Excel Workbook',
      c_int_dir TYPE string VALUE '/',
      c_def_filename TYPE string VALUE '*.XLSX' .

DATA: g_it_file_table TYPE TABLE OF file_table,
      g_wa_filetable  TYPE file_table,
      g_usr_act       TYPE i,
      g_rc            TYPE i.


PARAMETERS:      
                 p_file type rlgrap-filename.

AT SELECTION-SCREEN ON VALUE-REQUEST FOR p_file.
  PERFORM f4_excel_file USING p_file.

*&---------------------------------------------------------------------*
*&      Form  F4_EXCEL_FILE
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
FORM f4_excel_file USING pa_file TYPE localfile.

  CLEAR: g_wa_filetable,g_rc,g_usr_act.
  REFRESH: g_it_file_table.

  CALL METHOD cl_gui_frontend_services=>file_open_dialog
    EXPORTING
      window_title            = c_win_title
      default_filename        = c_def_filename
      initial_directory       = c_int_dir
    CHANGING
      file_table              = g_it_file_table
      rc                      = g_rc
      user_action             = g_usr_act
    EXCEPTIONS
      file_open_dialog_failed = 1
      cntl_error              = 2
      error_no_gui            = 3
      not_supported_by_gui    = 4
      OTHERS                  = 5.
  IF sy-subrc EQ 0 AND g_usr_act NE
              cl_gui_frontend_services=>action_cancel.
    READ TABLE g_it_file_table INTO g_wa_filetable INDEX 1.
    pa_file = g_wa_filetable.
  ELSEIF g_usr_act eq cl_gui_frontend_services=>action_cancel.
    MESSAGE s398(00) WITH text-e64.
  ENDIF.

  IF p_file IS INITIAL.
    MESSAGE s398(00) WITH text-e63.
  ENDIF.
ENDFORM.