RAP CDS Pattern: Vereinfachte Architektur mit Table Entities

1. Datenbanktabelle        (ZFLIGHT_BOOK)
2. Interface CDS View      (ZI_FlightBooking)
3. Projection CDS View     (ZC_FlightBooking)
4. Behavior Definition     (ZI_FlightBooking)
5. Behavior Implementation (ZBP_I_FLIGHTBOOKING)
6. Service Definition      (ZUI_FLIGHTBOOKING)
7. Service Binding         (ZUI_FLIGHTBOOKING_O4)

1. Table Entity            (ZI_FlightBooking) - Tabelle + View in einem
2. Behavior Definition     (ZI_FlightBooking)
3. Service Definition      (ZUI_FLIGHTBOOKING)
4. Service Binding         (ZUI_FLIGHTBOOKING_O4)

@EndUserText.label: 'Flugbuchung'
@AbapCatalog.enhancement.category: #NOT_EXTENSIBLE
@AbapCatalog.tableCategory: #TRANSPARENT
@AbapCatalog.deliveryClass: #A
@AbapCatalog.dataMaintenance: #RESTRICTED

define table entity zi_flightbooking {
  key client          : abap.clnt not null;
  key booking_id      : abap.numc(10) not null;

  // Geschäftsdaten
  flight_date         : abap.dats;
  carrier_id          : abap.char(3);
  connection_id       : abap.numc(4);
  customer_id         : abap.numc(10);

  // Buchungsdetails
  @Semantics.amount.currencyCode: 'zi_flightbooking.currency_code'
  flight_price        : abap.curr(15,2);
  currency_code       : abap.cuky;
  booking_status      : abap.char(1);

  // Administrative Felder (wichtig für RAP!)
  @Semantics.user.createdBy: true
  created_by          : abap.uname;
  @Semantics.systemDateTime.createdAt: true
  created_at          : abap.utclong;
  @Semantics.user.lastChangedBy: true
  last_changed_by     : abap.uname;
  @Semantics.systemDateTime.lastChangedAt: true
  last_changed_at     : abap.utclong;
  @Semantics.systemDateTime.localInstanceLastChangedAt: true
  local_last_changed  : abap.utclong;
}

managed implementation in class zbp_i_flightbooking unique;
strict ( 2 );

define behavior for zi_flightbooking alias FlightBooking
lock master
authorization master ( instance )
etag master local_last_changed
{
  // Standard CRUD - Framework übernimmt alles
  create;
  update;
  delete;

  // Felder schreibgeschützt
  field ( readonly ) booking_id;
  field ( readonly ) created_by, created_at, last_changed_by, last_changed_at;
  field ( readonly : update ) carrier_id, connection_id, flight_date;

  // Automatische Nummernvergabe
  field ( numbering : managed ) booking_id;

  // Einfache Actions
  action confirmBooking result [1] $self;
  action cancelBooking result [1] $self;

  // Validierung
  validation validateFlightDate on save { field flight_date; }
  validation validateCustomer on save { field customer_id; }

  // Determination für Status
  determination setInitialStatus on modify { create; }

  // Mapping - identisch da Table Entity
  mapping for zi_flightbooking corresponding;
}

@EndUserText.label: 'Flugbuchung Service'
define service ZUI_FLIGHTBOOKING {
  expose zi_flightbooking as FlightBooking;
}

Name:        ZUI_FLIGHTBOOKING_O4
Service:     ZUI_FLIGHTBOOKING
Binding Type: OData V4 - UI

CLASS zbp_i_flightbooking DEFINITION PUBLIC ABSTRACT FINAL
  FOR BEHAVIOR OF zi_flightbooking.
ENDCLASS.

CLASS zbp_i_flightbooking IMPLEMENTATION.
ENDCLASS.

CLASS lhc_flightbooking DEFINITION INHERITING FROM cl_abap_behavior_handler.
  PRIVATE SECTION.
    METHODS:
      confirmBooking FOR MODIFY
        IMPORTING keys FOR ACTION FlightBooking~confirmBooking
        RESULT result,

      cancelBooking FOR MODIFY
        IMPORTING keys FOR ACTION FlightBooking~cancelBooking
        RESULT result,

      validateFlightDate FOR VALIDATE ON SAVE
        IMPORTING keys FOR FlightBooking~validateFlightDate,

      validateCustomer FOR VALIDATE ON SAVE
        IMPORTING keys FOR FlightBooking~validateCustomer,

      setInitialStatus FOR DETERMINE ON MODIFY
        IMPORTING keys FOR FlightBooking~setInitialStatus.
ENDCLASS.

CLASS lhc_flightbooking IMPLEMENTATION.
  METHOD confirmBooking.
    " Status auf 'Bestätigt' setzen
    MODIFY ENTITIES OF zi_flightbooking IN LOCAL MODE
      ENTITY FlightBooking
        UPDATE FIELDS ( booking_status )
        WITH VALUE #( FOR key IN keys
          ( %tky = key-%tky
            booking_status = 'C' ) ).

    " Ergebnis zurückgeben
    READ ENTITIES OF zi_flightbooking IN LOCAL MODE
      ENTITY FlightBooking
        ALL FIELDS WITH CORRESPONDING #( keys )
      RESULT DATA(bookings).

    result = VALUE #( FOR booking IN bookings
      ( %tky = booking-%tky
        %param = booking ) ).
  ENDMETHOD.

  METHOD cancelBooking.
    MODIFY ENTITIES OF zi_flightbooking IN LOCAL MODE
      ENTITY FlightBooking
        UPDATE FIELDS ( booking_status )
        WITH VALUE #( FOR key IN keys
          ( %tky = key-%tky
            booking_status = 'X' ) ).

    READ ENTITIES OF zi_flightbooking IN LOCAL MODE
      ENTITY FlightBooking
        ALL FIELDS WITH CORRESPONDING #( keys )
      RESULT DATA(bookings).

    result = VALUE #( FOR booking IN bookings
      ( %tky = booking-%tky
        %param = booking ) ).
  ENDMETHOD.

  METHOD validateFlightDate.
    READ ENTITIES OF zi_flightbooking IN LOCAL MODE
      ENTITY FlightBooking
        FIELDS ( flight_date )
        WITH CORRESPONDING #( keys )
      RESULT DATA(bookings).

    LOOP AT bookings INTO DATA(booking).
      IF booking-flight_date < cl_abap_context_info=>get_system_date( ).
        APPEND VALUE #(
          %tky = booking-%tky
          %msg = new_message_with_text(
            severity = if_abap_behv_message=>severity-error
            text     = 'Flugdatum muss in der Zukunft liegen' )
          %element-flight_date = if_abap_behv=>mk-on
        ) TO reported-flightbooking.

        APPEND VALUE #( %tky = booking-%tky ) TO failed-flightbooking.
      ENDIF.
    ENDLOOP.
  ENDMETHOD.

  METHOD validateCustomer.
    " Kundenvalidierung implementieren
    READ ENTITIES OF zi_flightbooking IN LOCAL MODE
      ENTITY FlightBooking
        FIELDS ( customer_id )
        WITH CORRESPONDING #( keys )
      RESULT DATA(bookings).

    LOOP AT bookings INTO DATA(booking).
      IF booking-customer_id IS INITIAL.
        APPEND VALUE #(
          %tky = booking-%tky
          %msg = new_message_with_text(
            severity = if_abap_behv_message=>severity-error
            text     = 'Kunde muss angegeben werden' )
          %element-customer_id = if_abap_behv=>mk-on
        ) TO reported-flightbooking.

        APPEND VALUE #( %tky = booking-%tky ) TO failed-flightbooking.
      ENDIF.
    ENDLOOP.
  ENDMETHOD.

  METHOD setInitialStatus.
    READ ENTITIES OF zi_flightbooking IN LOCAL MODE
      ENTITY FlightBooking
        FIELDS ( booking_status )
        WITH CORRESPONDING #( keys )
      RESULT DATA(bookings).

    MODIFY ENTITIES OF zi_flightbooking IN LOCAL MODE
      ENTITY FlightBooking
        UPDATE FIELDS ( booking_status )
        WITH VALUE #( FOR booking IN bookings
          WHERE ( booking_status IS INITIAL )
          ( %tky = booking-%tky
            booking_status = 'O' ) ).
  ENDMETHOD.
ENDCLASS.

" ❌ Funktioniert NICHT in Table Entities
booking_status : zbooking_status_enum;

" ✅ Workaround: CHAR-Feld mit Value Help
booking_status : abap.char(1);

" ❌ Draft erfordert klassischen RAP Stack mit Projection View
with draft;

" ✅ Im CDS Pattern: Nur ohne Draft möglich
" Table Entity unterstützt kein draft table

" ❌ In Table Entity NICHT möglich
calculated_field : abap.char(10) = concat(carrier_id, connection_id);

" ✅ Klassische CDS View
define view entity ZI_FlightBooking as select from zflight_book {
  key booking_id,
  concat(carrier_id, connection_id) as FlightNumber
}

" ❌ Table Entity kann keine Assoziationen definieren
association [1..1] to zi_customer as _Customer;

" ✅ Workaround: Separate CDS View für Assoziationen

" 1. Table Entity bleibt als Datenbanktabelle erhalten
"    (Umbenennen zu ztable_flightbooking)

" 2. Neue Interface CDS View erstellen
define root view entity ZI_FlightBooking
  as select from ztable_flightbooking
{
  key booking_id as BookingId,
  " ... weitere Felder mit Aliasen
}

" 3. Behavior Definition anpassen
define behavior for ZI_FlightBooking
persistent table ztable_flightbooking
" ...