ABAP如何生成年月的输入帮助

在abap的设计过程中经常会出现账务期输入,格式为年月。如果我们使用spmon元素为参考,但是系统无输入帮助,用户常常出错，为了避免输入错误。我们可以自定义输入帮助,步骤如下:

1、定义选择变量
parameter p_spmon  type spmon default sy-datum+0(6) obligatory.
select-options s_spmon for s031-spmon default sy-datum+0(6) obligatory.

2、定义帮助子过程
form  monat_f4.
  data: begin of mf_dynpfields occurs 1.
          include structure dynpread.
  data: end   of mf_dynpfields.
  data: mf_returncode   like sy-subrc,
        mf_monat        like isellist-month,
        mf_hlp_repid    like sy-repid.
  field-symbols: <mf_feld>.

  get cursor field mf_dynpfields-fieldname.
  append mf_dynpfields.
  mf_hlp_repid = sy-repid.
  do 2 times.
    call function 'DYNP_VALUES_READ'
         exporting
              dyname               = mf_hlp_repid
              dynumb               = sy-dynnr
         tables
              dynpfields           = mf_dynpfields
         exceptions
              invalid_abapworkarea = 01
              invalid_dynprofield  = 02
              invalid_dynproname   = 03
              invalid_dynpronummer = 04
              invalid_request      = 05
              no_fielddescription  = 06
              undefind_error       = 07.
    if sy-subrc = 3.
      mf_hlp_repid = 'SAPLALDB'.
    else.
      read table mf_dynpfields index 1.
      translate mf_dynpfields-fieldvalue using '_ '.
      exit.
    endif.
  enddo.
  if sy-subrc = 0.
    call function 'CONVERSION_EXIT_PERI_INPUT'
         exporting
              input  = mf_dynpfields-fieldvalue
         importing
              output = mf_monat
         exceptions
              error_message = 1.
    if mf_monat is initial.
      mf_monat = sy-datlo(6).
    endif.
    call function 'POPUP_TO_SELECT_MONTH'
         exporting
              actual_month               = mf_monat
         importing
              selected_month             = mf_monat
              return_code                = mf_returncode
         exceptions
              factory_calendar_not_found = 01
              holiday_calendar_not_found = 02
              month_not_found            = 03.
    if sy-subrc = 0 and mf_returncode = 0.
      call function 'CONVERSION_EXIT_PERI_OUTPUT'
           exporting
                input  =  mf_monat
           importing
                output =  mf_dynpfields-fieldvalue.
      collect mf_dynpfields.
      call function 'DYNP_VALUES_UPDATE'
           exporting
                dyname               = mf_hlp_repid
                dynumb               = sy-dynnr
         tables
                dynpfields           = mf_dynpfields
           exceptions
                invalid_abapworkarea = 01
                invalid_dynprofield  = 02
                invalid_dynproname   = 03
                invalid_dynpronummer = 04
                invalid_request      = 05
                no_fielddescription  = 06
                undefind_error       = 07. 
    endif.
  endif.
endform.                               "MONAT_F4

3、定义输入帮助事件
at selection-screen on value-request for p_spmon.
  perform monat_f4.
at selection-screen on value-request for s_spmon-low.
  perform monat_f4.
at selection-screen on value-request for s_spmon-high.
  perform monat_f4.