Making a field in selection screen dynamic mandatory

Question

I have a parameter in the select option of a selection screen. The code is below:
TABLES:vbak,kna1,ekko,lfa1.
SELECTION-SCREEN BEGIN OF BLOCK b1 WITH FRAME TITLE TEXT-001.
PARAMETERS: rd1 RADIOBUTTON GROUP rd DEFAULT 'X' USER-COMMAND abc,
                            rd2 RADIOBUTTON GROUP rd,
                            rd3 RADIOBUTTON GROUP rd.
SELECTION-SCREEN END OF BLOCK b1.
SELECTION-SCREEN BEGIN OF BLOCK b2 WITH FRAME TITLE TEXT-002.
SELECT-OPTIONS:s_erdat FOR VBAK-ERDAT MODIF ID SAL,
                                   s_vbeln FOR VBAK-VBELN MODIF ID SAL,
                                   s_kunnr FOR KNA1-KUNNR MODIF ID SAL.
SELECTION-SCREEN END OF BLOCK b2.
SELECTION-SCREEN BEGIN OF BLOCK b3 WITH FRAME TITLE TEXT-003.
SELECT-OPTIONS:p_aedat FOR EKKO-AEDAT MODIF ID PUR,
                                   p_ebeln FOR EKKO-AEDAT MODIF ID PUR,
                                   p_lifnr FOR EKKO-AEDAT MODIF ID PUR.
SELECTION-SCREEN END OF BLOCK b3.
AT SELECTION-SCREEN OUTPUT.
  LOOP AT SCREEN.
    IF rd1 EQ 'X'.
      IF SCREEN-GROUP1 = 'SAL' OR SCREEN-GROUP1 EQ 'PUR'.
        SCREEN-ACTIVE = 0.
        MODIFY SCREEN.
      ENDIF.
    ENDIF.
    IF rd2 EQ 'X'.
      IF SCREEN-GROUP1 EQ 'PUR'.
        SCREEN-ACTIVE = 0.
        MODIFY SCREEN.
      ENDIF.
    ENDIF.
    IF rd3 EQ 'X'.
      IF SCREEN-GROUP1 EQ 'SAL'.
        SCREEN-ACTIVE = 0.
        MODIFY SCREEN.
      ENDIF.
    ENDIF.
  ENDLOOP.
Now the parameters s_erdap & _aedat  should both be dynamic mandatory. How this can be achieved?

Answer 1

Hi,
  This can be done in two ways:
1.
At  selection-screen output.
loop at screen.
IF rd1 EQ 'X'.
   if screen-name = 's_erdat-low' or screen-name = 'P_AEDAT'.
   screen-required = 1.
  modify screen.
  endif.
endif.
endloop.
the above code would make the lower value in select-option s_erdat and parameter p_aedat mandatory.
2.
at selection-screen.
if rd1 eq 'X'.
if s_erdat is initial.
  message 'PLease enter date'.
endif.
endif.
The above will fire an error when you hit execute and the rd1 is choosen and date is not entered
Himanshu