Friday, 10 November 2017

FOR expression in ABAP 7.40 – Best case scenarios

As we all know, the In-line declarations, operators and expressions available in 7.4 SP02 onward are taking the abap world by storm for last few years. For the new or the experienced abap-ers this is almost like fall in line or fall apart. The main idea is to write code easily, keep it lean and compact as much as possible.

But there is no end of debate that if the old school abap code is good enough to achieve everything then why complicate life ?Well with all that being said let us discuss about some simple best case scenarios of FOR expression which can seriously reduce no of lines of code and make it more compact. I feel this is one of the best addition among the new features.

Situation 1: To move values from a source internal table to a target internal table which has all the fields of source internal table + some additional fields ( say ). 

*Define structure
TYPES:
  BEGIN OF ty_struct1,
    field1 TYPE i,
    field2 TYPE string,
  END OF ty_struct1,
  BEGIN OF ty_struct2,
    field1 TYPE i,
    field2 TYPE string,
    field3 TYPE i,
  END OF ty_struct2.

*Define table types
TYPES:  gtt_struct1 TYPE STANDARD TABLE OF ty_struct1 WITH DEFAULT KEY,
        gtt_struct2 TYPE STANDARD TABLE OF ty_struct2 WITH DEFAULT KEY.

* Initialize source table with some random values
DATA(lt_source) = VALUE gtt_struct1(
    ( field1 = 1 field2 = 'A' )
    ( field1 = 2 field2 = 'B' ) ).

*Use like simple MOVE CORRESPONDING
DATA(lt_target1) = VALUE gtt_struct2( FOR lwa_source IN lt_source ( CORRESPONDING #( lwa_source ) ) ).
cl_demo_output=>display( lt_target1 ).

*Populate sy-tabix in the additional fields within the for loop
DATA(lt_target2) = VALUE gtt_struct2( FOR lwa_source IN lt_source
                            INDEX INTO index
                            LET base = VALUE ty_struct2( field3 = index )
                            IN ( CORRESPONDING #( BASE ( base ) lwa_source ) ) ).
cl_demo_output=>display( lt_target2 ).

*Populate any value or call custom method  in the additional fields within the for loop
DATA(lt_target3) = VALUE gtt_struct2( FOR lwa_source IN lt_source
             LET base = VALUE ty_struct2( field3 = 10 ) "<<< Custom method/any value
             IN ( CORRESPONDING #( BASE ( base ) lwa_source ) ) ).
cl_demo_output=>display( lt_target3 ).

Result

SAP ABAP Development, SAP ABAP Guides, SAP ABAP Live

Points to Note:

i) VALUE (Type of the internal table) is used for the in-line declaration of the internal table. Here structure and Type declaration is required before using VALUE operator. If you want to use VALUE # then type of the table must be already available and defined in the program i.e. the internal table need to be declared before.

iii)LT_TARGET3-FIELD3 is populated with a hard coded value 10 but in real life a custom method call can also be done in this place to pass the actual value of field3

Situation 2: Suppose we have an internal table and we want to create another range table with the values of one particular field from that internal table 

Sample code

*Get details from DB table
SELECT * FROM
  sflight
  INTO TABLE @DATA(lt_sflight)
  WHERE connid IN (17,555).

IF sy-subrc = 0.
*Prepare a range table
  DATA: lr_carrid  TYPE RANGE OF s_carr_id.
  lr_carrid = VALUE #( FOR ls_value IN lt_sflight ( sign = 'I'
                                                   option = 'EQ'
                                                   low = ls_value-carrid ) ).
  SORT lr_carrid BY low.
  DELETE ADJACENT DUPLICATES FROM lr_carrid
  COMPARING low.
  cl_demo_output=>display( lr_carrid ).
ENDIF.

Result

SAP ABAP Development, SAP ABAP Guides, SAP ABAP Live

Points to Note:

i) ‘@’ need to be used in the SELECT for in-line declaration of the internal table

Situation 3: There are 2 tables and based on which a third table need to be constructed 

*Define the structures of header & item table
TYPES:
  BEGIN OF comp,
    ebeln TYPE ebeln,
    bukrs TYPE bukrs,
  END OF comp.

*Declare table type
TYPES: gtt_comp   TYPE STANDARD TABLE OF comp WITH DEFAULT KEY,
       gtt_header TYPE STANDARD TABLE OF ekko WITH DEFAULT KEY,
       gtt_item   TYPE SORTED TABLE OF ekpo WITH NON-UNIQUE KEY ebeln
                               WITH NON-UNIQUE SORTED KEY key_combi COMPONENTS ebeln.

*Populate dummy values
DATA(lt_header) = VALUE gtt_header(
                      ( ebeln = '4500000027' )
                      ( ebeln = '4500000028' )
                      ( ebeln = '4500000029' ) ).

DATA(lt_item) = VALUE gtt_item( ( ebeln = '4500000027' ebelp = '000010' netwr = '100' bukrs = 'IND' )
                    ( ebeln = '4500000027' ebelp = '000020' netwr = '200' bukrs = 'IND' )
                    ( ebeln = '4500000027' ebelp = '000030' netwr = '300' bukrs = 'IND' )
                    ( ebeln = '4500000028' ebelp = '000010' netwr = '999' bukrs = 'USA' )
                    ( ebeln = '4500000029' ebelp = '000010' netwr = '25' bukrs = 'GB' )
                    ( ebeln = '4500000029' ebelp = '000020' netwr = '50' bukrs = 'GB' )
                    ( ebeln = '4500000029' ebelp = '000030' netwr = '100' bukrs = 'GB' )
                    ( ebeln = '4500000029' ebelp = '000040' netwr = '150' bukrs = 'GB' ) ).

*Now populate the values of Compor from item table to a new table
DATA(lt_comp) = VALUE gtt_comp(
                    FOR ls_header IN lt_header
                    FOR ls_item IN lt_item WHERE ( ebeln = ls_header-ebeln )
                    (  ebeln = ls_header-ebeln
                       bukrs = ls_item-bukrs ) ).

SORT lt_comp BY ebeln.
DELETE ADJACENT DUPLICATES FROM lt_comp
COMPARING ebeln.

cl_demo_output=>display( lt_comp ).

Result

SAP ABAP Development, SAP ABAP Guides, SAP ABAP Live

Points to note:

i) VALUE (Type of the internal table) is used for the in-line declaration of the internal table.

Situation 4: Summation of item values and populate the total in header table 

◉ Use the code from situation 3 for the declaration part

*Now sum up all the netwr for a particular purchase order
LOOP AT lt_comp ASSIGNING FIELD-SYMBOL(<lfs_comp>).
  <lfs_comp>-netwr = REDUCE netwr( INIT lv_netwr TYPE netwr
                       FOR ls_item IN
                       FILTER #( lt_item
                       USING KEY key_combi
                       WHERE ebeln = <lfs_comp>-ebeln )
                       NEXT lv_netwr = lv_netwr + ls_item-netwr ).
ENDLOOP.

cl_demo_output=>display( lt_comp ).

Result

SAP ABAP Development, SAP ABAP Guides, SAP ABAP Live

Points to note:

i) LT_ITEM has to be sorted table for using the FILTER option

ii) REDUCE with FOR is like a nested loop only difference is that you can’t debug all the iterations

Situation 5: Append new values into an internal table which already have some values 

Use the code from situation 3 for the declaration part

◉*Append new records in item table
lt_item = VALUE #( BASE lt_item
          ( ebeln = '4500000030' ebelp = '000010' netwr = '1099' bukrs = 'CAN' ) ).

cl_demo_output=>display( lt_item ).

Result

SAP ABAP Development, SAP ABAP Guides, SAP ABAP Live

Points to Note:

i) Here VALUE with # has been used since type of LT_ITEM is already defined

All the above 5 examples are simple and self explanatory. If you try them in your system I am sure it will be easier to grasp. If you have any questions let me know. There are tons of feature added with the new expressions and operators. Please feel free to add any other good use of FOR expression, if I have missed. I am planning to write more in this space like when to use FOR ( New ABAP ) and when to use LOOP ( old abap ) and related topics in future.

No comments:

Post a Comment