Create a fieldcatalog dynamically

Question

Hey everyone,
I need to realize a method which creates dynamically a fieldcatalog. The call of the method looks like this:
  CALL METHOD me->describe_struct_for_fcat
    EXPORTING
      im_tab = it_data. "type: data
I have a vague idea how to do this:
1. get the type of the im_tab
2. Some kind of loop at the type of the im_tab where filling the row for the fcat and appending it to the fcat.
I would be pleased if you can post a code snippet or something, which I can copy.
Looking forward to your answers.
BR Fabian

Answer 1

try this, but note, you will have do figure out how to get the correct length and decimals for field types P or I
REPORT  ZCA_BOB_CL_ABAP_STRUCTDESCR_X.
Data: r_descr type REF TO cl_abap_structdescr,
      wa_comp TYPE abap_compdescr.
types: begin of wa_int_tab,
        mandt type mandt,
        matnr type matnr,
        werks type WERKS_D,
        lgort type LGORT_D,
        min_qty type MINLF,
       end of wa_int_tab.
data: it_int_tab TYPE STANDARD TABLE OF wa_int_tab.
data: wk_int_tab like LINE OF  it_int_tab.
Data: wk_length(6) type n,
      wk_decimals(6) type n.
START-OF-SELECTION.
r_descr ?= cl_abap_typedescr=>describe_by_data( wk_int_tab ).
Loop at r_descr->components into wa_comp.
   If wa_comp-type_kind = 'C'
   or wa_comp-type_kind = 'D'
   or wa_comp-type_kind = 'N'.
    Divide wa_comp-length by 2.
  Else.
** go out to tables DD03L and  DD04L to get LENG and DECIMALS
  Endif.
   write:/ wa_comp-name,
           wa_comp-type_kind,
           wa_comp-length,
           wa_comp-decimals.
EndLoop.