How to find out, if a dynamic genereated structure already exists in DDIC?

Question

Good morning developers,
can you help me with that above mentioned problem?
I'm about to write a report which manages to change tablecontrol(s) to alvgrids.
My current problem is, that i read all fields of a tablecontrol and generate its <b>structure</b> dynamically ( temporary just during runtime of the report, not stored yet ).
Now I have to know, if this generated structure already exists in the DDIC, or not.
If not, i have to create a type of my generated structure and store it in the DDiC.
I know that there s a FM called <b>"COMPARE_STRUCTURE_DATA"</b>.
But i think i have to know the name of the existing structure in DDiC.
Is there also a way for a recursive search in ddic?
If not:  when i read the fields of my tablecontrol from the DDiC, i read from ddic-table D021S. In its field "FNAM" it contains for example SFLIGHT-carrid ( <table><column> ).
I could split 'FNAM' into table and column. How do i search for the structuretype of a table?
Thx for your replys, post points waiting
Regards
Basti

Answer 1

Hello Bastian
All dynpro fields (including table controls) are either based on DDIC structures of program variables. Thus, the following coding will return you the required answer.
*& Report  ZUS_SDN_RTTI_IS_DDICTYPE
REPORT  zus_sdn_rtti_is_ddictype.
TYPE-POOLS: abap.
TYPES: BEGIN OF ty_s_line.
TYPES:   field(3)  TYPE n.
TYPES:   flag(1)   TYPE c.
" INCLUDE TYPE knb1.
TYPES: END OF ty_s_line.
TYPES: ty_t_line    TYPE STANDARD TABLE OF ty_s_line
                    WITH DEFAULT KEY.
DATA:
  gs_line    TYPE ty_s_line,
  gs_knb1    TYPE knb1,
  go_tabdescr      TYPE REF TO cl_abap_tabledescr,
  go_strucdescr    TYPE REF TO cl_abap_structdescr.
START-OF-SELECTION.
  go_strucdescr ?= cl_abap_tabledescr=>describe_by_data( gs_line ).
  IF ( go_strucdescr->is_ddic_type( ) = abap_true ).
    WRITE: / 'gs_line is a DDIC type'.
  ELSE.
    WRITE: / 'gs_line is not a DDIC type'.
  ENDIF.
  SKIP.
  go_strucdescr ?= cl_abap_tabledescr=>describe_by_data( gs_knb1 ).
  IF ( go_strucdescr->is_ddic_type( ) = abap_true ).
    WRITE: / 'gs_knb1 is a DDIC type'.
  ELSE.
    WRITE: / 'gs_knb1 is not a DDIC type'.
  ENDIF.
END-OF-SELECTION.
However, if a dynpro field is based on a type defined within the program the situation may be more complex if the type includes DDIC structures (as shown above). But I am sure you will master this obstacle.
Regards
  Uwe