Validation and substitute in SAP ABAP issue

irst of all you have to define your user exit in the FORM routine GET_EXIT_TITLES with the correct

exit type (EXITS-PARAM).

The exit type required for your FORM routine is C_EXIT_PARAM_CLASS A where complete type is transferred as a parameter.

Bear in mind that this exit type can only be used for callup points with complete documents (3).

Hereafter an example for your issue

  exits-name  = 'USDN'.
  exits-param = c_exit_param_class.
  exits-title = 'SDN Test 4 GSBER Substitution'.
  append exits.


*&---------------------------------------------------------------------*
*&      USER EXIT USDN
*&---------------------------------------------------------------------*
*  GSBER substitution
*----------------------------------------------------------------------*
form usdn using bool_data type gb002_015.

  data wa_bseg type bseg.
  loop at bool_data-bseg into wa_bseg where koart = 'K'.
    exit.
  endloop..
   
 loop at bool_data-bseg into bseg where koart = 'T'.
        bseg-gsber = wa_bseg-gsber.
        modify bool_data-bseg from bseg.
 endloop.

endform.

FORM RK001 USING bool_data TYPE gb002_015    "TYPE GB002_<boolean class of aspect 001>
           CHANGING b_result.
*  BREAK-POINT.
  DATA: gv_dmbtr2  TYPE bseg-dmbtr,
        gv_dmbtr1 TYPE bseg-dmbtr,
        gv_netwr  TYPE ekpo-netwr,
        gv_sub    TYPE bseg-dmbtr.
  CLEAR: gv_dmbtr2,gv_dmbtr1.

  DATA wa_bseg TYPE bseg.
  LOOP AT bool_data-bseg INTO wa_bseg. "where koart = 'K'.
    gv_dmbtr2 = gv_dmbtr2 + wa_bseg-dmbtr.
    CLEAR: wa_bseg.
  ENDLOOP.
  READ TABLE bool_data-bseg INTO wa_bseg INDEX 1.
  IF sy-subrc EQ 0.
    SELECT dmbtr,ebeln FROM bseg INTO TABLE @DATA(gt_bseg) WHERE ebeln = @wa_bseg-ebeln.
    IF sy-subrc EQ 0.
      LOOP AT gt_bseg INTO DATA(gs_bseg).
        gv_dmbtr1 = gv_dmbtr1 + gs_bseg-dmbtr.
        CLEAR: gs_bseg.
      ENDLOOP.
    ENDIF.
    SELECT ebeln,netwr FROM ekpo INTO TABLE @DATA(gt_ekpo) WHERE ebeln EQ @wa_bseg-ebeln.
    IF sy-subrc EQ 0.
      LOOP AT gt_ekpo INTO DATA(gs_ekpo).
        gv_netwr = gv_netwr + gs_ekpo-netwr.
        CLEAR: gs_ekpo.
      ENDLOOP.
    ENDIF.
  ENDIF.
  GV_SUB = GV_DMBTR2 + GV_DMBTR.
  IF GV_SUB LE GV_NETWR.
   ELSE.
    MESSAGE 'Posting Amount Issue Pleae fix IT' TYPE 'E'.
  ENDIF.
ENDFORM.

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