Refresh problem in CL_GUI_ALV_TREE

Question

Hi Experts,
I am taking an object name as input and based on the input value, fetching data from the table and displaying it in the form of a tree, using the class CL_GUI_ALV_TREE. The outtab is passed empty to the set_table_for_first_display method. Now, when I go back, enter a new object name and click on display, the data that is used to build the tree gets updated properly, all the add_node calls get executed fine, but the tree does not get refreshed. It gets refreshed properly if I restart the transaction and start with the new object. I am calling the method frontend_update to update the screen, still there is no change. I am clearing the tree object and building the tree from scratch with the new data. But it does not change.
Is there any clearing of cache required? I am missing anything that is not refreshing the tree. Any help on this would be greatly appreciated since I am stuck with this for a long time now. Thank you!
Regards,
Nithya
Edited by: Nithya S on Apr 8, 2008 8:57 AM

Answer 1

hi nithya..........
check this code....hope it will be useful
report  y13816_alv_tree_with_oops.
§1a. Define reference variables
data: g_alv_tree type ref to cl_gui_alv_tree,
      g_custom_container type ref to cl_gui_custom_container,
      gt_sflight type sflight occurs 0,
      g_max type i value 255.
end-of-selection.
call screen 100.
*&      Module  STATUS_0100  OUTPUT
      text
module status_0100 output.
  set pf-status 'MENU_BAR'.
if g_alv_tree is initial.
  perform init_tree.
  call method cl_gui_cfw=>flush
   exceptions
     cntl_system_error = 1
     cntl_error        = 2.
  if sy-subrc <> 0.
    call function 'POPUP_TO_INFORM'
      exporting
        titel         = 'Automation Queue failure'(801)
        txt1          = 'Internal error:'(802)
        txt2          = 'A method in the automation queue'(803)
        txt3          = 'caused a failure.'(804).
  endif.
endif.
endmodule.                 " STATUS_0100  OUTPUT
*&      Form  init_tree
      text
-->  p1        text
<--  p2        text
form init_tree .
§1b. Create ALV Tree Control and corresponding Container.
create container for alv-tree
data: l_tree_container_name(30).
l_tree_container_name = 'CONTAINER'.
create object g_custom_container
  exporting
    container_name = l_tree_container_name
  exceptions
    cntl_error                  = 1
    cntl_system_error           = 2
    create_error                = 3
    lifetime_error              = 4
    lifetime_dynpro_dynpro_link = 5.
  if sy-subrc <> 0.
    message x208(00) with 'ERROR'(100).
  endif.
Creating Tree Control
create object g_alv_tree
  exporting
    parent              = g_custom_container
    node_selection_mode = cl_gui_column_tree=>node_sel_mode_single
    item_selection      = 'X'
    no_html_header      = 'X'
    no_toolbar          = 'X'
  exceptions
    cntl_error                   = 1
    cntl_system_error            = 2
    create_error                 = 3
    lifetime_error               = 4
    illegal_node_selection_mode  = 5
    failed                       = 6
    illegal_column_name          = 7.
  if sy-subrc <> 0.
    message x208(00) with 'ERROR'.                          "#EC NOTEXT
  endif.
§2. Create Hierarchy-header
The simple ALV Tree uses the text of the fields which were used
for sorting to define this header. When you use
the 'normal' ALV Tree the hierarchy is build up freely
by the programmer this is not possible, so he has to define it
himself.
data: l_hierarchy_header type treev_hhdr.
  perform build_hierarchy_header changing l_hierarchy_header.
§3. Create empty Tree Control
IMPORTANT: Table 'gt_sflight' must be empty. Do not change this table
(even after this method call). You can change data of your table
by calling methods of CL_GUI_ALV_TREE.
Furthermore, the output table 'gt_outtab' must be global and can
only be used for one ALV Tree Control.
  call method g_alv_tree->set_table_for_first_display
    exporting
      i_structure_name    = 'SFLIGHT'
      is_hierarchy_header = l_hierarchy_header
    changing
      it_outtab           = gt_sflight. "table must be empty !
§4. Create hierarchy (nodes and leaves)
  perform create_hierarchy.
§5. Send data to frontend.
  call method g_alv_tree->frontend_update.
endform.                    " init_tree
*&      Form  build_hierarchy_header
      text
     <--P_L_HIERARCHY_HEADER  text
form build_hierarchy_header  changing
                                p_hierarchy_header type treev_hhdr.
p_hierarchy_header-heading   = 'Month/Carrier/Date'.
p_hierarchy_header-tooltip   = 'Flights in a Month'.
p_hierarchy_header-width     = 30.
p_hierarchy_header-width_pix = ' '.
endform.                    " build_hierarchy_header
*&      Form  create_hierarchy
      text
-->  p1        text
<--  p2        text
form create_hierarchy .
data: ls_sflight type sflight,
      lt_sflight type sflight occurs 0,
      l_yyyymm(6) type c,
      l_yyyymm_last(6) type c,
      l_carrid like sflight-carrid,
      l_carrid_last like sflight-carrid,
      l_month_key type lvc_nkey,
      l_carrid_key type lvc_nkey,
      l_last_key type lvc_nkey.
§4a. Select data
select * from sflight into table lt_sflight up to g_max rows.
§4b. Sort output table according to your conceived hierarchy
We sort in this order:
   year and month (top level nodes, yyyymm of DATS)
     carrier id (next level)
        day of month (leaves, dd of DATS)
sort lt_sflight by fldate0(6) carrid fldate6(2).
Note: The top level nodes do not correspond to a field of the
output table. Instead we use data of the table to invent another
hierarchy level above the levels that can be build by sorting.
§4c. Add data to tree
loop at lt_sflight into ls_sflight.
Prerequesite: The table is sorted.
You add a node everytime the values of a sorted field changes.
Finally, the complete line is added as a leaf below the last
node.
  l_yyyymm = ls_sflight-fldate+0(6).
  l_carrid = ls_sflight-carrid.
Top level nodes:
  if l_yyyymm <> l_yyyymm_last.
    l_yyyymm_last = l_yyyymm.
*Providing no key means that the node is added on top level:
    perform add_month using    l_yyyymm
                      changing l_month_key.
The month changed, thus, there is no predecessor carrier
    clear l_carrid_last.
  endif.
Carrier nodes:
(always inserted as child of the last month
which is identified by 'l_month_key')
  if l_carrid <> l_carrid_last.
    l_carrid_last = l_carrid.
    perform add_carrid_line using    ls_sflight
                                     l_month_key
                            changing l_carrid_key.
  endif.
Leaf:
(always inserted as child of the last carrier
which is identified by 'l_carrid_key')
    perform add_complete_line using    ls_sflight
                                       l_carrid_key
                              changing l_last_key.
endloop.
endform.                    " create_hierarchy
*&      Form  add_month
      text
form add_month  using    p_yyyymm type c
                         p_relat_key type lvc_nkey
                changing p_node_key type lvc_nkey.
data: l_node_text type lvc_value,
      ls_sflight  type sflight,
      l_month(15) type c.
get month name for node text
perform get_month using p_yyyymm
                  changing l_month.
l_node_text = l_month.
add node:
ALV Tree firstly inserts this node as a leaf if you do not provide
IS_NODE_LAYOUT with field ISFOLDER set. In form 'add_carrid_line'
the leaf gets a child and thus ALV converts it to a folder
automatically.
call method g_alv_tree->add_node
  exporting
    i_relat_node_key = p_relat_key
    i_relationship   = cl_gui_column_tree=>relat_last_child
    i_node_text      = l_node_text
    is_outtab_line   = ls_sflight
  importing
    e_new_node_key   = p_node_key.
endform.                    " get_month
*&      Form  get_month
      text
     -->P_P_YYYYMM  text
     <--P_L_MONTH  text
form get_month  using    p_yyyymm
                changing p_month.
Returns the name of month according to the digits in p_yyyymm
data: l_monthdights(2) type c.
l_monthdights = p_yyyymm+4(2).
case l_monthdights.
  when '01'.
   p_month = 'January'.
  when '02'.
   p_month = 'February'.
  when '03'.
   p_month = 'March'.
  when '04'.
   p_month = 'April'.
  when '05'.
   p_month = 'May'.
  when '06'.
   p_month = 'June'.
  when '07'.
   p_month = 'July'.
  when '08'.
   p_month = 'August'.
  when '09'.
   p_month = 'September'.
  when '10'.
   p_month = 'October'.
  when '11'.
   p_month = 'November'.
  when '12'.
   p_month = 'December'.
endcase.
concatenate p_yyyymm+0(4) '->' p_month into p_month.
endform.                    " get_month
*&      Form  add_carrid_line
      text
     -->P_LS_SFLIGHT  text
     -->P_L_MONTH_KEY  text
     <--P_L_CARRID_KEY  text
form add_carrid_line  using    ps_sflight  type sflight
                               p_relat_key type lvc_nkey
                      changing p_node_key  type lvc_nkey.
data: l_node_text type lvc_value,
      ls_sflight  type sflight.
add node
ALV Tree firstly inserts this node as a leaf if you do not provide
IS_NODE_LAYOUT with field ISFOLDER set. In form 'add_carrid_line'
the leaf gets a child and thus ALV converts it to a folder
automatically.
l_node_text = ps_sflight-carrid.
call method g_alv_tree->add_node
  exporting
    i_relat_node_key = p_relat_key
    i_relationship   = cl_gui_column_tree=>relat_last_child
    i_node_text      = l_node_text
    is_outtab_line   = ls_sflight
  importing
    e_new_node_key   = p_node_key.
endform.                    " add_carrid_line
*&      Form  add_complete_line
      text
form add_complete_line  using    ps_sflight   type sflight
                                 p_relat_key  type lvc_nkey
                        changing p_node_key   type lvc_nkey.
data: l_node_text type lvc_value.
write ps_sflight-fldate to l_node_text mm/dd/yyyy.
add leaf:
ALV Tree firstly inserts this node as a leaf if you do not provide
IS_NODE_LAYOUT with field ISFOLDER set.
Since these nodes will never get children they stay leaves
(as intended).
call method g_alv_tree->add_node
exporting
  i_relat_node_key = p_relat_key
  i_relationship   = cl_gui_column_tree=>relat_last_child
  i_node_text      = l_node_text
  is_outtab_line   = ps_sflight
importing
  e_new_node_key   = p_node_key.
endform.                    " add_complete_line
*&      Module  USER_COMMAND_0100  INPUT
      text
module user_command_0100 input.
case sy-ucomm.
  when 'EXIT'.
   leave program.
endcase.
endmodule.                 " USER_COMMAND_0100  INPUT
reward if useful
cheers,
rekha