Select particular listbox value on start of Dynpro? - listbox

Question

I have a custom dialog dynpro including an input field named DYN_MATNR as listbox for which I have included a list of particular materials as selection.
How can I set a specific material (of that list) as selected when the dialog dynpro is opened?
PBO of dialog dynpro:
data lt_values type vrm_values.
select matnr,
maktx
into table #data(lt_materials)
from makt
where matnr in #so_matnr
and spras = 'D'
order by matnr.
loop at lt_materials assigning field-symbol(<material>).
append initial line to lt_values assigning field-symbol(<value>).
<value>-key = <material>-matnr.
<value>-text = <material>-maktx.
endloop.
call function 'VRM_SET_VALUES'
exporting
id = 'DYN_MATNR'
values = lt_values
exceptions
id_illegal_name = 1
others = 2.
if sy-subrc <> 0.
" ...
endif.
This works and it shows the list of materials as listbox values. To select a particular material I have included the FM DYNP_VALUES_UPDATE afterwards and also in PBO but this did not work:
data lv_stepl type syst-stepl.
call function 'DYNP_GET_STEPL'
importing
povstepl = lv_stepl
exceptions
stepl_not_found = 1
others = 2.
if sy-subrc <> 0.
" ...
endif.
data(lt_dynpfields) = value dynpread_tabtype(
( fieldname = 'DYN_MATNR'
stepl = lv_stepl
fieldvalue = gcl_helper->get_matnr( ) " matnr which should be selected is stored here
fieldinp = space )
).
call function 'DYNP_VALUES_UPDATE'
exporting
dyname = sy-repid
dynumb = sy-dynnr
tables
dynpfields = lt_dynpfields
exceptions
invalid_abapworkarea = 1
invalid_dynprofield = 2
invalid_dynproname = 3
invalid_dynpronummer = 4
invalid_request = 5
no_fielddescription = 6
undefind_error = 7
others = 8.
if sy-subrc <> 0.
" ...
endif.
I am also not able to directly set DYN_MATNR as it is not available in PBO.
Any hints?

Answer 1

Got it:
You need to additionally define a global(!) variable with the name and (wished) type of the input field (e.g. in the top include of the report or in a separate include of the dynpro logic):
data dyn_matnr type matnr.
Then you can set the initial value of the dynpro field in PBO directly:
dyn_matnr = gcl_helper->get_matnr( ).
As this becomes rather irritating when using various dialog dynpros I recommend including the dynpro number in those variables and input fields.