Modern ABAP in one sitting

Why a functional consultant needs to read ABAP

On a technical MDG role you write the rules you used to specify. Most MDG code is small: a validation BAdI is often 40 lines, a derivation 20. What makes it look hard is the modern syntax. MDG enhancements live in the middle two layers below: classes, and the 7.4+ expression syntax.

Which syntax can you use?

NetWeaver 7.40 brought inline declarations; every S/4HANA release runs on 7.50 or later, so on S/4 MDG you can use everything here.

Reading data: one SELECT, step by step

The modern SELECT: commas between fields, @ before every ABAP variable, and @DATA(...) declaring the result table on the spot. Click through the steps.

DATA(lv_since) = CONV d( sy-datum - 365 ).

SELECT partner, bu_group, name_org1, crdat
  FROM but000
  WHERE type  = '2'            " 2 = organisation
    AND crdat >= @lv_since
  ORDER BY crdat DESCENDING
  INTO TABLE @DATA(lt_orgs)
  UP TO 500 ROWS.

IF sy-subrc <> 0.
  RETURN.  " nothing found
ENDIF.

Try it: write the SELECT

SELECT partner, name_org1
  FROM but000
  WHERE crdat >= ______@DATA(lt_orgs)lineslv_since@lv_sinceDATA(lt_orgs)count
  INTO TABLE ______@DATA(lt_orgs)lineslv_since@lv_sinceDATA(lt_orgs)count.

DATA(lv_count) = ______@DATA(lt_orgs)lineslv_since@lv_sinceDATA(lt_orgs)count( lt_orgs ).

Classic to modern

Standard SAP is full of the left side. Read both; write the right.

Constructor expressions

They build a value in one statement, like a Data Services transform: rows in, rows out. A table expression such as lt_x[ lifnr = ... ] raises CX_SY_ITAB_LINE_NOT_FOUND when no row matches.

Let the database count

A data-quality report (partners per country with an empty postal code) is one SELECT ... GROUP BY joining BUT000, BUT020 and ADRC. Counting in the database beats reading everything and counting in ABAP.

Classes and interfaces

Every MDG BAdI is a class implementing an SAP interface. Think of a class as a function group whose functions share data, and an interface as a published signature many classes can implement. Keep rules in plain classes, such as ZCL_TAX_RULE_DE implementing ZIF_TAX_RULE~IS_VALID, so they can be tested without MDG.

ABAP Unit: test the rule, not the screen

A test class is marked FOR TESTING, lives with the class it tests and never touches production data. Run it with Ctrl+Shift+F10 in ADT (the Eclipse editor; use it for all new code). Ask an AI assistant for tests too, and run them before trusting its code.

CLASS ltc_tax_rule DEFINITION FINAL FOR TESTING
  DURATION SHORT RISK LEVEL HARMLESS.
  PRIVATE SECTION.
    METHODS short_german_id_fails FOR TESTING.
ENDCLASS.

CLASS ltc_tax_rule IMPLEMENTATION.
  METHOD short_german_id_fails.
    DATA lo_cut TYPE REF TO zif_tax_rule.
    lo_cut = NEW zcl_tax_rule_de( ).
    cl_abap_unit_assert=>assert_false(
      act = lo_cut->is_valid( iv_country = 'DE' iv_tax_number = 'DE1234' )
      msg = 'Short German VAT ID must fail' ).
  ENDMETHOD.
ENDCLASS.

Try it: a short dump

Check yourself