BPS Variables of Type Exit (How To Document)

Question

Hello,
I'm trying to restrict entries for (say) variable #2, based on the selection of variable #1. 
I've just realised characteristic relationships cannot be used and need to use a user exit.  I've gone through the "How To" on BPS Variables of Type Exit and have gotten the function modules to working properly. 
However when the function module attempts to pass the data to BPS Variable #2, BPS gives an ERROR saying that in order to write new values into variable #2, the variable must have a replacement path "USER DEFINED VALUES".
However this is not possible as the replacement path must be set to "USER EXIT" so the function module can be activated.
The only way around this is to tell the function module which BPS Variable it should choose to write the data to, if so does anyone the ABAP to store values into a BPS Variable.
Right now would appreciate any comment on this.
Kind regards,
Marinos

Answer 1

Hi Marc,
Yes, the How To paper answers my problem, and when I run the program via se37 the correct variable selections are being populated in table ETO_CHARSEL.  However when values are passed to the BPS Variable, the first information message read "The Conditions were Adapted"  but no values are passed to the variable.  Then a second error message "Entry not possible, var does not have replacement type user-spec vals."  This seems to be a conundrum as the variable needs to be set as user-exit.
Any thoughts?
Marinos
My Z_SIMPLE_RELATION code is
FUNCTION Z_SIMPLE_RELATION.
""Local Interface:
*"  IMPORTING
*"     VALUE(I_AREA) TYPE  UPC_Y_AREA
*"     VALUE(I_VARIABLE) TYPE  UPC_Y_VARIABLE
*"     VALUE(I_CHANM) TYPE  UPC_Y_CHANM
*"     VALUE(ITO_CHANM) TYPE  UPC_YTO_CHA
*"  EXPORTING
*"     VALUE(ETO_CHARSEL) TYPE  UPC_YTO_CHARSEL
Change constant according to your needs
TABLES: /BIC/MTASSTCAT.
CONSTANTS:
l_source_var TYPE upc_y_variable VALUE 'TCAPASST',
l_source_area TYPE upc_y_area VALUE 'TCAP001P',
l_use_restricted_values TYPE boole-boole VALUE 'X',
l_buffer_call TYPE boole-boole VALUE 'X'.
DATA:
l_subrc LIKE sy-subrc,
ls_return LIKE bapiret2,
l_type LIKE upc_var-vartype,
lto_varsel_all TYPE upc_yto_charsel,
lto_varsel TYPE upc_yto_charsel,
lto_var TYPE upc_yto_charsel,
lt_chavl TYPE /bic/PTASSTCAT occurs 0,
ls_chavl like line of lt_chavl,
lto_chanm type upc_yto_cha.
read source value
CALL FUNCTION 'Z_VARIABLE_GET_DETAIL'
EXPORTING
i_area = l_source_area
i_variable = l_source_var
i_buffer = l_buffer_call
IMPORTING
e_subrc = l_subrc
es_return = ls_return
e_type = l_type
eto_varsel_all = lto_varsel_all
eto_varsel = lto_varsel
eto_chanm = lto_chanm.
IF l_subrc <> 0.
MESSAGE i136(upc_fw) WITH l_source_var.
Values of variable &1 cannot be determined
EXIT.
ENDIF.
now, you are free to determine the logic on how to
derive the values based on the source values.
Example 1: determine the next year
Assumptions:
- we have only a single year in the selection
- the variable is of type characteristic
DATA: ls_varsel TYPE upc_ys_charsel,
l_next_year(4) TYPE n,
l_entries TYPE i.
We have a single value for the year and only one characteristic
=> our value is stored in the first line
IF l_use_restricted_values IS INITIAL.
lto_var = lto_varsel_all.
ELSE.
lto_var = lto_varsel.
ENDIF.
READ TABLE lto_var INTO ls_varsel INDEX 1.
check prerequisites:
- record found?
IF sy-subrc <> 0.
MESSAGE i147(upc_fw) WITH l_source_var.
Variable &1 does not contain any values
EXIT.
ENDIF.
- exactly one record and characteristic?
DESCRIBE TABLE lto_var LINES l_entries.
IF l_entries <> 1.
MESSAGE i534(upc) WITH l_source_var.
Variable &1 must be restricted to a value
EXIT.
ENDIF.
SELECT * FROM /BIC/PTASSTCAT INTO TABLE lt_chavl
  WHERE asset_clas = ls_varsel-low.
  if sy-subrc <> 0.
    MESSAGE e026(upc) WITH ls_varsel-low '0ASSET_CLAS'.
Attribute value not found
  exit.
endif.
ls_varsel-seqno = '0000'.
ls_varsel-chanm = '/BIC/TASSTCAT'.
LOOP AT lt_chavl INTO ls_chavl.
ls_varsel-seqno = ls_varsel-seqno + 1.
ls_varsel-low = ls_chavl-/BIC/TASSTCAT.
APPEND ls_varsel TO eto_charsel.
ENDLOOP.
ENDFUNCTION.