WD4A with ALV, populating the header with values from the table

Question

I have WDA application that list schedule agreement headers in one ALV and when you select one the line items show in the second ALV2 below. We show quantity and net value  in 13 monthly buckets beginning with the validity data. The function returns the month text in columns I want to change the header based on the months returned. So instead of QNTY1, QNTY2 it would be 01/2008, 01/2008 etc. But ALV2 is initialized when the page is built and if I change the ALV2 settings after the line item function call they are not updated. On the page. Is there anyway I can do this???
It tried put the code in the EXECUTE function method, and I tried WDMODIFYVIEW but the ALV is not refreshed.
Thanks
David

Answer 1

Thanks for your help, I know I am probably doing something dumb but it is driving me crazy.
I have debugged I can see the text change in the debugger but it doesn't show up on the screen. I removed the code from from the WDDOINIT. So am doing everything in the ONACTIONGETDETAIL to ensure that it is not being overwritten. I can change the 'number of lines', remove print button, change a field to an icon etc, but the column header doesn't change. If I put the same code in the WDDOINIT the column header does change. Everything else works in both places.
*First ALV config
    l_ref_cmp_usage =   wd_this->wd_cpuse_alv( ).
    IF l_ref_cmp_usage->has_active_component( ) IS INITIAL.
      l_ref_cmp_usage->create_component( ).
    ENDIF.
    DATA lo_interfacecontroller TYPE REF TO iwci_salv_wd_table.
    lo_interfacecontroller = wd_this->wd_cpifc_alv( ).
    DATA lo_value TYPE REF TO cl_salv_wd_config_table.
    lo_value = lo_interfacecontroller->get_model( ).
*activate extended functions of the alv.
    cl_salv_wd_model_table_util=>if_salv_wd_table_util_stdfuncs~set_all(
       r_model = lo_value ).
    lo_value->if_salv_wd_table_settings~set_visible_row_count( '10' ).
    lo_value->if_salv_wd_table_settings~set_selection_mode( '06' ).
    lo_value->if_salv_wd_std_functions~set_pdf_allowed( abap_false ).
    DATA lr_column_settings TYPE REF TO if_salv_wd_column_settings.
    DATA lr_column TYPE REF TO cl_salv_wd_column.
    DATA lr_column_header TYPE REF TO cl_salv_wd_column_header.
    lr_column_settings ?= lo_value.
    lr_column = lr_column_settings->get_column( 'VBTYP' ).
    lr_column->delete_header( ).
    lr_column_header = lr_column->create_header( ).
    lr_column_header->set_ddic_binding_field( if_salv_wd_c_column_settings=>ddic_bind_none ).
    lr_column_header->set_text( '200708' ).
*change column to icon
    lr_column = lo_value->if_salv_wd_column_settings~get_column( 'AUART_DESC' ).
    CREATE OBJECT lr_image.
    lr_image->set_source_fieldname( 'AUART_DESC' ).
    lr_column->set_cell_editor( lr_image ). "Display images in column
Thanks again.
David