How to catch the event for change dropdown value in alv

Question

it has a column output by dropdown in alv. the dropdown type cl_salv_wd_uie_dropdown_by_idx.
now the problem is if change the dropdown value, i want to catch the event to change another column value.
how can i do it?

Answer 1

This part contains other ALV initialization code
*... init ColumnSettings
  DATA:
        lr_column_settings TYPE REF TO if_salv_wd_column_settings.
  lr_column_settings ?= wd_this->r_table.
  DATA:
        lt_columns TYPE salv_wd_t_column_ref.
  lt_columns = lr_column_settings->get_columns( ).
  DATA:
        ls_column     TYPE salv_wd_s_column_ref,
        lr_col_header TYPE REF TO cl_salv_wd_column_header,
        l_tooltip     TYPE string.
  LOOP AT lt_columns INTO ls_column.
    CASE ls_column-id.
      WHEN 'PLANETYPE'.
        DATA:
              lr_drdn_by_key TYPE REF TO cl_salv_wd_uie_dropdown_by_key.
        CREATE OBJECT lr_drdn_by_key
          EXPORTING
            selected_key_fieldname = ls_column-id.
        lr_drdn_by_key->set_key_visible( abap_true ).
        ls_column-r_column->set_cell_editor( lr_drdn_by_key ).
      WHEN OTHERS.
    ENDCASE.
ENDLOOP.
  DATA:
        node_info TYPE REF TO if_wd_context_node_info,
        lt_valueset   TYPE STANDARD TABLE OF wdr_context_attr_value,
        l_value       TYPE wdr_context_attr_value.
  node_info = wd_context->get_node_info( ).
  node_info = node_info->get_child_node( 'FLIGHT_INFO' ).
data : lt_sflight type STANDARD TABLE OF sflight,
       ls_sflight like LINE OF lt_sflight.
SELECT * from sflight into TABLE lt_sflight.
LOOP at lt_sflight into ls_sflight.
  l_value-value = ls_sflight-planetype.
  l_value-text  = ls_sflight-planetype.
  INSERT l_value into TABLE lt_valueset.
  ENDLOOP.
  node_info->set_attribute_value_set(
  name = 'PLANETYPE'
  value_set = lt_valueset ).