Usage of update-bapi and getdetail-bapi within one view

Question

Hello,
i'm a student and i'm new to webdynpro and abap. Im trying to get data through a bapi into some screens and want to update some of these inputfields back through an update-bapi.
I get all the needed data by a getdetails-bapi  and can show the data within binded inputfields, but how could i get the infos about which field was changed and how could i implement an update through the update-bapi?
It is possible, that a view with two inputfileds gets the data through the getdetails-bapi and after a change in this fields there will be an update through a update-bapi, after pushing a button?
Could you give me an example code, or could you explane me a way for implementing these?
Thanks for your help!
John

Answer 1

Hi John,
changes made at Contexts are stored in a table WDR_CONTEXT_CHANGE_LIST. So you can retrieve the old and new values from the table.
Please follow the below steps :
1. Create a context node (Ex:Changes) with dict.str wdr_context_change.
2. Then create one subnode under Changes ex(details) with two attributes old_value and new_value with the type of string.
3. Then write the below code at any button action.
DATA: l_ref_componentcontroller TYPE REF TO ig_componentcontroller .
    DATA: l_changes                 TYPE        wdr_context_change_list,
          l_subnode                 type ref to if_wd_context_node,
          l_subnodedata             type if_USERLOG=>element_details.
    field-symbols: <change> type wdr_context_change,
                   <new>    type data,
                   <old>    type data.
    l_ref_componentcontroller =   wd_this->get_componentcontroller_ctr( ).
    l_changes = l_ref_componentcontroller->get_changes( ).
    data: l_node type ref to if_wd_context_node.
    l_node = wd_context->get_child_node( 'CHANGES' ).
    l_node->bind_table( l_changes ).
    loop at l_changes assigning <change>.
      if <change>-old_value is not initial and <change>-new_value is not initial.
        l_subnode = l_node->get_child_node( index = sy-tabix name = 'DETAILS' ).
        assign <change>-new_value->* to <new>.
        assign <change>-old_value->* to <old>.
*        l_subnodedata-new_value_string = cl_wdr_conversion_utils=>to_string( value = <new> ).
*        l_subnodedata-old_value_string = cl_wdr_conversion_utils=>to_string( value = <old> ).
         l_subnodedata-new_value_string = <new>.
        l_subnodedata-old_value_string = <old>.
*        l_subnodedata-new_value_string = 'AC'.
*        l_subnodedata-old_value_string = 'CD'.
        l_subnode->bind_structure( l_subnodedata ).
       endif.
      endloop.
So now your context has the changed records.
Thanks.