Conversion of type "u" to type "v" not supported (cl_abap_tabledescr)

Question

Help! I am struggling with implementing a solution using cl_abap_tabledescr.
At below  statement :
<f_interim_data> = <f_ref_data>.
I get the error:
Conversion of type "u" to type "v" not supported. 
Coding:
DATA:
    l_r_tabledescr      TYPE  REF TO cl_abap_tabledescr,
    l_r_itab            type  ref to data,
    l_r_data_ref        type  ref to data,
    l_r_data            type  ref to data.
  field-symbols:
    <gt_itab>          TYPE ANY TABLE,
    <gt_itab_BCCMP07>  TYPE STANDARD TABLE.
  field-symbols:
    <f_ref_data>            type  any,
    <f_new_data>            type  any,
    <f_interim_data>        type  any.
  go_tdescr ?= cl_abap_tabledescr=>describe_by_data( i_th_ref_data ).
  go_sdescr ?= go_tdescr->get_table_line_type( ).
  gd_tabnam     = 'I_TH_REF_DATA'.
  loop at go_sdescr->components INTO gs_component.
    "   Build fieldname
    CONCATENATE gd_tabnam gs_component-name INTO gd_tabfield
                                            SEPARATED BY '-'.
    CLEAR: gs_comp.
    gs_comp-name  = gs_component-name.
    gs_comp-type ?= cl_abap_datadescr=>describe_by_data( gd_tabfield ).
    APPEND gs_comp TO gt_components.
  endloop.
Begin create dynamic standard table copy of I_TH_REF_DATA
  "   Create instances of dynamic structure and dynamic internal table
  go_sdescr_new  = cl_abap_structdescr=>create( P_COMPONENTS = gt_components p_strict = abap_false ).
  go_tdescr      = cl_abap_tabledescr=>create( go_sdescr_new ).
  "   Create data refence followed by table creation
  CREATE DATA gdo_handle TYPE HANDLE go_tdescr.
  ASSIGN gdo_handle->* TO <gt_itab_BCCMP07>.
End create dynamic standard table copy of I_TH_REF_DATA
"Generate ref record
  create data l_r_data_ref like line of <gt_itab_BCCMP07>.
  assign l_r_data_ref->* to <f_interim_data>.
  loop at i_th_ref_data assigning <f_ref_data>.
     <f_interim_data> = <f_ref_data>.
      append <f_interim_data> to <gt_itab_BCCMP07>.

Answer 1

Hi ,
Check the code below which is similar to waht you are doing. It gets the existing fields from a structure and then adds some extra fields to it ( decimals 3 )and creates a dyn table. If you need it with decimals 2 then use WTGXXX data element
DATA:lf_startdate TYPE sy-datum,
       li_index(2) TYPE n,
       la_datum TYPE type_date.
  DATA:i_comp TYPE cl_abap_structdescr=>component_table,
       i_tot_comp TYPE cl_abap_structdescr=>component_table,
       lf_struct TYPE REF TO cl_abap_structdescr,
       lf_element TYPE REF TO cl_abap_elemdescr,
       la_comp LIKE LINE OF i_comp,
       lf_new_type TYPE REF TO cl_abap_structdescr,
       lf_new_tab TYPE REF TO cl_abap_tabledescr.
  CLEAR: lf_startdate,li_index,la_datum,i_comp[],i_tot_comp[].
*--Getting Compoents from existing type
  lf_struct ?= cl_abap_typedescr=>describe_by_name( 'TYPE_PUT' ).
  i_comp = lf_struct->get_components( ).
  APPEND LINES OF i_comp TO i_tot_comp.
*--Adding weekly bukets fields based on date in selection screen
  DO.
    li_index = sy-index.
    IF lf_startdate GT s_lfdat-high.
      EXIT.
    ENDIF.
    IF li_index EQ 1.
      PERFORM get_first_day_of_week USING s_lfdat-low
                                    CHANGING lf_startdate.
      la_datum-dat = lf_startdate .
*--Element Description
      lf_element ?= cl_abap_elemdescr=>describe_by_name( 'MESXXX' ).
      CONCATENATE 'MES0' li_index  INTO la_comp-name.
      la_datum-field = la_comp-name.
*--Field Type
      la_comp-type =
        cl_abap_elemdescr=>get_p( p_length = lf_element->length
                                  p_decimals = lf_element->decimals ).
      APPEND la_comp TO i_tot_comp.
      CLEAR: la_comp.
      APPEND la_datum TO i_datum.
      CLEAR: la_datum.
      CONTINUE.
    ENDIF.
    lf_startdate = lf_startdate + 6.
    la_datum-dat = lf_startdate .
    lf_element ?= cl_abap_elemdescr=>describe_by_name( 'MESXXX' ).
    CONCATENATE 'MES0' li_index  INTO la_comp-name.
    la_datum-field = la_comp-name.
    la_comp-type =
      cl_abap_elemdescr=>get_p( p_length = lf_element->length
                                p_decimals = lf_element->decimals ).
*--Fill the component table
    APPEND la_comp TO i_tot_comp.
    CLEAR: la_comp.
    APPEND la_datum TO i_datum.
    CLEAR: la_datum.
  ENDDO.
*--Create type
  TRY.
      lf_new_type = cl_abap_structdescr=>create( i_tot_comp ).
    CATCH cx_sy_struct_creation .                       "#EC NO_HANDLER
  ENDTRY.
*--Create Table type
  TRY.
      lf_new_tab =
      cl_abap_tabledescr=>create( p_line_type = lf_new_type
      p_table_kind = cl_abap_tabledescr=>tablekind_std p_unique = ' ' ).
    CATCH cx_sy_table_creation .                        "#EC NO_HANDLER
  ENDTRY.
*--data to handle the new table type
  CREATE DATA wf_data TYPE HANDLE lf_new_tab.
*--data to handle the work area
  CREATE DATA wf_str TYPE HANDLE lf_new_type.
*--Assign to fs
  ASSIGN wf_data->* TO <fs_tab>.
  ASSIGN wf_str->* TO <fs_line>.