Editable ALV - Particular Lines Display and Edit Problem

Question

Hi,
I have developed a program which updates the Custom tables in the database.
I am using cl_gui_alv_grid in the module pool program. I am making all the fields editable using ls_fcat-edit = 'X'.
But as per my requirement in the change mode of the same data base entry, the user should not be able to change the existing data (like PO line items).
My requirement is for a particular Purchase Order if there are line items, when I open the Purchase Order in the change mode all the existing line items should be in display mode and I need to provide the user to add more lines.
Say the PO has 3 line items, in the Grid, it should be like all the existing 3 line items should be in display mode and rest of the lines should be in editable mode which will give the option for the user to add more line items for the same PO.
Here it is not Purchase Order,  I just compared as an example.
Logic I am using.
I am building the internal table with a serial numbers from 1-99 and this particular column will be in display mode in the ALV Grid. Using the class cl_gui_alv_grid.
Capturing all the data entered using event handler with method handle_data_changed.
Please tell me how do I set the particular lines in display mode and others in editable mode within the same internal table.
Thanks

Answer 1

Hi Prabhu,
thanks for the logic, but for some reason the it is not working for me.  Please see the below logic and let me know what I am missing.
I am not passing anything related to style to the method Set table for first display.
Is this correct  it_outtab            = gt_outtab[].
or because of the below method
CALL METHOD g_grid->set_ready_for_input the lines are not actually coming in display mode
DATA : BEGIN OF gt_outtab OCCURS 0.
INCLUDE TYPE zaodoperation.
DATA: celltab TYPE lvc_t_styl ."--->for styles.....
DATA: END OF gt_outtab.
DATA ls_celltab TYPE lvc_s_styl .
  DATA lt_celltab TYPE lvc_t_styl .
  DATA v_tabix TYPE sy-tabix.
  IF gt_outtab[] IS NOT INITIAL.
*Setting the non editiable mode
    LOOP AT gt_outtab INTO gs_outtab.
      IF gs_outtab-heatnum IS NOT INITIAL.
        LOOP AT gt_fieldcat INTO gs_fieldcat.
          ls_celltab-fieldname = gs_fieldcat-fieldname.
          ls_celltab-style = cl_gui_alv_grid=>mc_style_disabled."-->no edit.....
          INSERT ls_celltab INTO TABLE lt_celltab.
        ENDLOOP.
        INSERT LINES OF lt_celltab INTO TABLE  gs_outtab-celltab.
        MODIFY gt_outtab FROM gs_outtab.
        CLEAR : gs_outtab.
*      else.
*        v_tabix = sy-tabix.
      ENDIF.
*      delete gt_outtab INDEX v_tabix.
    ENDLOOP.
  ENDIF.
CALL METHOD g_grid->set_table_for_first_display
    EXPORTING
      is_layout            = gs_layout
      it_toolbar_excluding = gt_exclude
    CHANGING
      it_fieldcatalog      = gt_fieldcat
      it_outtab            = gt_outtab[].
* set editable cells to ready for input
  CALL METHOD g_grid->set_ready_for_input
    EXPORTING
      i_ready_for_input = 1.
  CALL METHOD g_grid->register_edit_event
    EXPORTING
      i_event_id = cl_gui_alv_grid=>mc_evt_enter.
Thanks