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Understanding Dynamic Tables (RTTS)

Hi guys,

While i was playing with dynamic tables and i can't figure how to get the exact data type from data elements.

I'll explain better in code

* Declare Data. ( dynamic fields )


            gs_fields TYPE char30,

             gt_comp     TYPE cl_abap_structdescr=>component_table,

            gs_comp     LIKE LINE OF gt_comp,

             go_element  TYPE REF TO cl_abap_elemdescr,

            go_struct   TYPE REF TO cl_abap_structdescr.

LOOP AT gt_fields INTO gs_fields.

*   Element descripiton

     go_element ?= cl_abap_elemdescr=>describe_by_name( gs_fields ).

*   Field name

     MOVE gs_fields TO gs_comp-name.

*   Field type

     gs_comp-type cl_abap_elemdescr=>get_c( go_element->length ).

     APPEND gs_comp TO gt_comp.


This code is good and i can manage to build a dynamic table from this.


1) gs_fields ( where i store the name of the fields ) can only be chart type ( get_c () ). if i send a field which type is integer i get dump and is normal.

2) when i display with alv i don't get any description in my column header.

I managed to get a better result but not as i wanted. ( i want a completely dynamic table )

-> Define a type in my program. add fields. ( ex: matnr type mara-matnr, mara-mtart etc )

-> Get components from existing type:

   go_struct ?= cl_abap_typedescr=>describe_by_name( 'TY_MY_TYPE' ).

   gt_comp  = lo_struct->get_components( ).

I tried different options but none was good. I think is still something regarding how i fill my go_element i think. Do you have any ideas?

Thank you,

Alex F.

Former Member
Former Member replied

Hi Alexandru Fediuc,

the best thing is to use existing data elements to create the dynamic table.

So you may extend your table that it carries a fieldname and a datatype (data element or DDIC structure and component) for each field to be created.

See here the (tested) sample program:

FORM dyndata .


    BEGIN OF ty_dyndata,

    fieldname              TYPE fieldname,

    data_type              TYPE string,

    END OF ty_dyndata,

    ty_t_dyndata           TYPE STANDARD TABLE OF ty_dyndata.


    lt_dyndata             TYPE ty_t_dyndata,

    lo_salv_table          TYPE REF TO cl_salv_table,

    lo_structdescr         TYPE REF TO cl_abap_structdescr,

    lo_typedescr           TYPE REF TO cl_abap_typedescr,

    lo_tabledescr          TYPE REF TO cl_abap_tabledescr,

    lr_data                TYPE REF TO data,

    lr_dyntable            TYPE REF TO data,

    lt_component           TYPE cl_abap_structdescr=>component_table.


    <dyndata>              TYPE ty_dyndata,

    <component>            TYPE LINE OF cl_abap_structdescr=>component_table,

    <dyntable>             TYPE table.

* example with 2 fields

  APPEND INITIAL LINE TO lt_dyndata ASSIGNING <dyndata>.

  <dyndata>-fieldname = 'ORDER'.

  <dyndata>-data_type = 'VBAK-VBELN'.

  APPEND INITIAL LINE TO lt_dyndata ASSIGNING <dyndata>.

  <dyndata>-fieldname = 'ITEM'.

  <dyndata>-data_type = 'VBAP-POSNR'.

  APPEND INITIAL LINE TO lt_dyndata ASSIGNING <dyndata>.

  <dyndata>-fieldname = 'COMPANY'.

  <dyndata>-data_type = 'BUKRS'.

  APPEND INITIAL LINE TO lt_dyndata ASSIGNING <dyndata>.

  <dyndata>-fieldname = 'COUNT'.

  <dyndata>-data_type = 'I'.

* creation of dynamic table

  LOOP AT lt_dyndata ASSIGNING <dyndata>.


        CREATE DATA lr_data TYPE (<dyndata>-data_type).

        APPEND INITIAL LINE TO lt_component ASSIGNING <component>.

        <component>-type ?= cl_abap_datadescr=>describe_by_data_ref( lr_data ).

        <component>-name = <dyndata>-fieldname.

      CATCH cx_root.

* error handling

* ... cannot create data of type <dyndata>-data_type



* new description object for structured type

  lo_structdescr = cl_abap_structdescr=>create( lt_component ).

* create table description for structure decription

  lo_tabledescr = cl_abap_tabledescr=>create(

                  p_line_type  = lo_structdescr

                  p_table_kind = cl_abap_tabledescr=>tablekind_std

                  p_unique     = abap_false ).

* create dynamic data object (table)

  CREATE DATA lr_dyntable TYPE HANDLE lo_tabledescr.

* use table

  ASSIGN lr_dyntable->* TO <dyntable>.

* append a couple of records

  DO 10 TIMES.

    APPEND INITIAL LINE TO <dyntable>.


* create SALV object




          r_salv_table   = lo_salv_table


          t_table        = <dyntable>


    CATCH cx_salv_msg .


* display table

  lo_salv_table->display( ).

ENDFORM.                    " DYNDATA

As you may have noticed, I used field-symbols quite frequently. For a reason: INTO <work area> is NEVER faster than the use of field-symbols, field-symbols save memory and they can be used much more flexible.

We have column headers for data created based on structure fields (VBAK-VBELN) and data elements (BUKRS), not for direct type (I).

Also, the ALV consistency check reports a warning for this field:

BTW: The ALV consistency check can be invoked by holding CTRL and SHIFT keys, pointing in an empty area of the grid and double-right-click the mouse. (If someone can tell me how to catch a double-right-click and the CTRL-SHIFT key press, he or she is invited for dinner )

The description in column header is taken from field catalog. If you use SALV object model, the object model will create the field catalog it self. It works better if the data element refers to a dictionary DOMAIN, direct data type in data element causes inconsistencies.

Hope you can make use of this,



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