Changing Outbound delivery data before creation

BADI and User exit for OB before even Delivery data checks starts.
- before delivery split criteria is determined.
- before sending data to GN_DELIVERY_CREATE
- changing data for OB created from STO - BAPI_OUTB_DELIVERY_CREATE_STO

Basic idea is to target the Delivery creation structure - it_komdlgn

inside GN_DELIVERY_CREATE at the beginning it self you have a BADI. But this BADI has all IMPORTING parameters for the Method - IMPORT. SO its not directly possible to change the data.
Use STACK table assignment using Field-symbols to change the data.

BADI - shp_badi_gn_delivery_create
Implementation:
IF_EX_SHP_GN_DELIVERY_CREATE~IMPORT

Requirement - to change the LFDAT field which is read from EKET table and Spitting of MATNR is done based on that.
METHOD if_ex_shp_gn_delivery_create~import.

  DATA: lt_range TYPE TABLE OF zrange.
  FIELD-SYMBOLS:  TYPE zrange,
                  TYPE komdlgn,
                  TYPE ANY TABLE.

  DATA: lv_name TYPE tdobname,
        lt_lines TYPE STANDARD TABLE OF tline,
        ls_lines LIKE LINE OF lt_lines,
        ls_lips  TYPE lips,
        lv_ebeln TYPE ebeln,
        lv_ekorg TYPE ekorg,
        lv_bsart TYPE bsart,
        lv_prog TYPE string VALUE '(SAPLV50S)XKOMDLGN[]'.

  CONSTANTS: co_savelang  TYPE thead-tdspras VALUE 'E'.

*** Dynamic accessing of variables in Stack programs
  ASSIGN (lv_prog) TO .
  CHECK  IS ASSIGNED.


* Read table available in BADI to get SA num
  READ TABLE xkomdlgn ASSIGNING  INDEX 1.
  CHECK sy-subrc EQ 0.
  MOVE -vgbel TO lv_name."for READ_TEXT
  MOVE -vgbel TO lv_ebeln."for SELECT query

* Get SA details for verification with ZRANGE table
  SELECT ekorg bsart UP TO 1 ROWS INTO (lv_ekorg,lv_bsart)
    FROM ekko
    WHERE ebeln EQ lv_ebeln.
  ENDSELECT.

* Read ZRANGE for triggering of below logic
  SELECT * FROM zrange INTO TABLE lt_range
    WHERE application  = 'HUBSTOSA' AND
          program_name = 'MV50AFZ1' AND
          identifier  = lv_ekorg.


  IF sy-subrc EQ 0.
    SORT lt_range BY fieldname.
    READ TABLE lt_range ASSIGNING  WITH KEY fieldname = 'BSART' BINARY SEARCH.
    IF sy-subrc NE 0 AND  IS NOT ASSIGNED.
      RETURN.
    ELSEIF  IS ASSIGNED.
      IF -low NE lv_bsart.
        RETURN.
      ENDIF.
    ENDIF.
  ELSE.
    RETURN.
  ENDIF.
*

  CHECK sy-tcode EQ 'ZSD_SCHEDULE_HUB' OR sy-batch EQ 'X'.

*
  CALL FUNCTION 'READ_TEXT'
    EXPORTING
*     client                  = sy-mandt
      id                      = 'L04'
      language                = co_savelang
      name                    = lv_name
      object                  = 'EKPO'
    TABLES
      lines                   = lt_lines
    EXCEPTIONS
      id                      = 1
      language                = 2
      name                    = 3
      not_found               = 4
      object                  = 5
      reference_check         = 6
      wrong_access_to_archive = 7
      OTHERS                  = 8.
  IF sy-subrc <> 0.
    RETURN.
  ENDIF.
  READ TABLE lt_lines INTO ls_lines INDEX 2.

  LOOP AT  ASSIGNING .
    MOVE ls_lines-tdline TO -lfdat.
  ENDLOOP.

ENDMETHOD.