topic Re: Question with LOOP AT itab in Application Development and Automation Discussions

Question with LOOP AT itab

Former Member — Fri, 20 May 2016 14:50:11 GMT

The documentation says that itab is a functional Operator so i replaced it with a functional method. Normal Loop works fine but GROUP BY gets error Messages "no Group binding" . If i insert a helper variable for the functional method result the code works.

Why?

I put some Example Coding in the attachment (modified SAP demo Report)

Re: Question with LOOP AT itab

Jelena_Perfiljeva — Fri, 20 May 2016 19:00:08 GMT

Say what? Is this an ABAP question? We have an operator called "itab" now? In which release? What documentation did you read?

Sorry, I ain't opening any zip files to check the code examples. If you have a specific question then kindly find a specific [small] fragment in your code it pertains to and post it directly in the question.

Re: Question with LOOP AT itab

Sandra_Rossi — Sat, 21 May 2016 03:32:48 GMT

At first glance, I had the same reaction as Jelena, but I opened the zip files and copied the code to a test program, and I must say I didn't understand, maybe it's a bug and you could post a message to SAP, and I'm now waiting for answers from experts.

Anyway, I agree with Jelena, and your question is worth re-posting with a minimalist code (inside post, not inside zip) so that you touch more people, and it will be easier to understand it. See example posts by Suhas Saha (for instance: http://scn.sap.com/thread/3881351 )

Re: Question with LOOP AT itab

Former Member — Mon, 30 May 2016 07:16:41 GMT

Sorry misspelled

I put in the correct citation:

"Executes a table iteration as a loop across an internal table itab. itab is a functional operand position."

Unfortunately I only have an old Version of Internet Explorer and the post editing Features of this Editor are not functioning very well. I can't really insert any code examples but I will try for my next posting.

Re: Question with LOOP AT itab

Former Member — Mon, 30 May 2016 14:07:50 GMT

The SAP Version used was NW 7.40 SP 13

This editor really is browser dependant:

Testreport:


REPORT  zflpi_test.
CLASS demo DEFINITION.
  PUBLIC SECTION.
    CLASS-METHODS:
      main.
  PRIVATE SECTION.
    TYPES:
      BEGIN OF line,
        key TYPE i,
        num TYPE i,
      END OF line,
      itab TYPE STANDARD TABLE OF line WITH DEFAULT KEY.
ENDCLASS.


CLASS demo IMPLEMENTATION.
  METHOD main.
    DATA(out) = cl_demo_output=>new( ).


    DATA:
      BEGIN OF aggregate,
        sum TYPE i,
        max TYPE i,
        min TYPE i,
        avg TYPE decfloat34,
      END OF aggregate.
  "wont work with group by
  "loop at zcl_flpi_demo=>create( )->get_data( ) assinging field-symbol(<wa>)
  "works fine
    data(numbers) = zcl_flpi_demo=>create( )->get_data( ).
    LOOP AT numbers ASSIGNING FIELD-SYMBOL(<wa>)
         GROUP BY ( key = <wa>-key  count = GROUP SIZE )
         ASCENDING
         ASSIGNING FIELD-SYMBOL(<group_key>).
      out->next_section( |Group Key: { <group_key>-key }| ).
      DATA(members) = VALUE itab( FOR m IN GROUP <group_key> ( m ) ).
      aggregate-sum = REDUCE i( INIT sum = 0
                                FOR m IN GROUP <group_key>
                                NEXT sum = sum + m-num ).
      aggregate-max = REDUCE i( INIT max = 0
                                FOR m IN GROUP <group_key>
                                NEXT max = nmax( val1 = max
                                                 val2 = m-num ) ).
      aggregate-min = REDUCE i( INIT min = 101
                                FOR m IN GROUP <group_key>
                                NEXT min = nmin( val1 = min
                                                 val2 = m-num ) ).
      aggregate-avg = aggregate-sum / <group_key>-count.
      SORT members BY num DESCENDING.
      out->write( members
        )->write( aggregate ).
    ENDLOOP.
    out->display( ).
  ENDMETHOD.
ENDCLASS.


START-OF-SELECTION.
  demo=>main( ).

And the global class:


CLASS zcl_flpi_demo DEFINITION
  PUBLIC
  FINAL
  CREATE PUBLIC .


  PUBLIC SECTION.
    TYPES:
      BEGIN OF line,
        key TYPE i,
        num TYPE i,
      END OF line,
      itab TYPE STANDARD TABLE OF line WITH DEFAULT KEY.
    CLASS-METHODS create
      RETURNING
        value(r_result) TYPE REF TO zcl_flpi_demo.
    METHODS get_data RETURNING VALUE(result) type itab.
  PROTECTED SECTION.
  PRIVATE SECTION.
ENDCLASS.


CLASS zcl_flpi_demo IMPLEMENTATION.
  METHOD create.
    CREATE OBJECT r_result.
  ENDMETHOD.


  METHOD get_data.
    DATA(keys) = 3.
    DATA(lines) = 10.
    DATA(rnd_key) = cl_abap_random_int=>create(
      seed = CONV i( sy-uzeit ) min = 1 max = keys ).
    DATA(rnd_num) = cl_abap_random_int=>create(
      seed =  sy-uzeit + 1  min = 1 max = 100 ).
    result = VALUE #( FOR j = 1 UNTIL j > lines
                       ( key = rnd_key->get_next( )
                         num = rnd_num->get_next( ) ) ).
  ENDMETHOD.
ENDCLASS.

Re: Question with LOOP AT itab

SuhaSaha — Mon, 30 May 2016 14:44:02 GMT

Nice question. Seems to me like an undocumented feature

Anyway this statement has me wondering (ABAP Keyword Documentation)


If the internal table is specified as the return value or result of a functional method, a constructor expression, or a table expression, the value is persisted for the duration of the loop. Afterwards, it is no longer possible to access the internal table.

Because with GROUP BY addition the LOOP is processed in 2 steps -

Grouping
Loop at Group

I guess the internal table is not accessible in the second step and therefore you get the error.

Calling in to pitch in his views

BR,

Suhas

Re: Question with LOOP AT itab

retired_member — Fri, 10 Jun 2016 05:54:15 GMT

Hello,

There was indeed a gap in the documentation in Release 7.40 that was closed in Release 7.50.

See LOOP AT GROUP.

"This loop is only possible within a LOOP across an internal table with the addition GROUP BY,

for which the internal table itab is specified directly as a data object and not specified as the result of a call or expression "

The reason for this is neatly explained by Suhas

Horst

Re: Question with LOOP AT itab

Ruediger_Plantiko — Fri, 10 Jun 2016 06:18:53 GMT

Hello Horst and Suhas - the argument is not really conceivable.

OK, the internal table that resulted from a functional expression call is an anonymous data object. But if it is internally possible to keep this data object for one processing step (as in a normal loop) - why shouldn't it also be internally possible to keep it for a second processing step (as in the GROUP BY loop)

So let's keep the answer simple: it's not implemented.

Regards, Rüdiger