如何使用ＢＡＤＩ修改ＰＯ (processing to ME21N )

Requirement:

Populate EVERS [ Shipping Point ] at the time of purchase order ceration. Shipping point should be derivated from the shipping point on sales order [ if PO created from in reference to a sales order ].

Processing:

This is an example to show - how to achieve post-processing [ follow-on processing ] functionality using BADIs [ Business Add-inn ] or user-exits.

Find the relevant BADI using transaction SE18. In this case BADI ME_PURCHDOC_POSTED is used.
Further, implement the BADI using transaction SE19.
In Attributes section of BADI, define a STATIC attribute as PO_NUMBER. Static means the attribute will keep its value between the calls. This will be checked to ensure that same PO will not be processed twice. Also these kind of user-exits and BADIs might get called recursively and get caught into an infinite loop, if not coded properly. Rememeber that this BADI is at the time of PO save and then you are again trying to change & save the Purchase Order from within the BADI.
BAPI to change Purchase Order 'BAPI_PO_CHANGE' will be called IN BACKGROUND TASK to ensure that it will be called when COMMIT WORK is encountered.
Don't forget to activate the BADI implementation in SE19.

method IF_EX_ME_PURCHDOC_POSTED~POSTED .

DATA: wa_ekpo like line of IM_EKPO,
      lt_po_item type standard table of BAPIMEPOITEM,
      lt_po_itemx type standard table of BAPIMEPOITEMX,
      wa_po_item type BAPIMEPOITEM,
      wa_po_itemx type BAPIMEPOITEMX,
      lt_return type standard table of BAPIRET2.

*data: ls_ebeln type BAPIMEPOHEADER-PO_NUMBER.

check im_ekko-ebeln ne PO_NUMBER.

PO_NUMBER = im_ekko-ebeln.

LOOP AT IM_EKPO into wa_ekpo.

wa_po_item-PO_ITEM = wa_ekpo-ebelp.
* EVERS to be derived
wa_po_item-SHIPPING = 'C'.
APPEND wa_po_item to lt_po_item .

wa_po_itemx-PO_ITEM = wa_ekpo-ebelp.
wa_po_itemx-SHIPPING = 'X'.
APPEND wa_po_itemx to lt_po_itemx.
ENDLOOP.

CALL FUNCTION 'BAPI_PO_CHANGE' IN BACKGROUND TASK
   EXPORTING
     purchaseorder                = PO_NUMBER
*    POHEADER                     =
*    POHEADERX                    =
*    POADDRVENDOR                 =
*    TESTRUN                      =
*    MEMORY_UNCOMPLETE            =
*    MEMORY_COMPLETE              =
*    POEXPIMPHEADER               =
*    POEXPIMPHEADERX              =
*    VERSIONS                     =
    NO_MESSAGING                 = 'X'
    NO_MESSAGE_REQ               = 'X'
    NO_AUTHORITY                 = 'X'
    NO_PRICE_FROM_PO             = 'X'
* IMPORTING
*    EXPHEADER                    =
*    EXPPOEXPIMPHEADER            =
   TABLES
     RETURN                       = lt_return
     POITEM                       = lt_po_item
     POITEMX                      = lt_po_itemx
*    POADDRDELIVERY               =
*    POSCHEDULE                   =
*    POSCHEDULEX                  =
*    POACCOUNT                    =
*    POACCOUNTPROFITSEGMENT       =
*    POACCOUNTX                   =
*    POCONDHEADER                 =
*    POCONDHEADERX                =
*    POCOND                       =
*    POCONDX                      =
*    POLIMITS                     =
*    POCONTRACTLIMITS             =
*    POSERVICES                   =
*    POSRVACCESSVALUES            =
*    POSERVICESTEXT               =
*    EXTENSIONIN                  =
*    EXTENSIONOUT                 =
*    POEXPIMPITEM                 =
*    POEXPIMPITEMX                =
*    POTEXTHEADER                 =
*    POTEXTITEM                   =
*    ALLVERSIONS                  =
*    POPARTNER                    =
           .