Clases de Excepcion en ABAP: CX_, TRY-CATCH y Manejo de Errores

Kategorie
ABAP-OO
Veröffentlicht
Autor
Johannes

Las Clases de Excepcion son el mecanismo moderno de manejo de errores en ABAP. Reemplazan a los codigos de retorno clasicos y permiten manejo de errores estructurado con TRY-CATCH.

Jerarquia de Excepciones

CX_ROOT (Abstracta)
├── CX_STATIC_CHECK    - Debe declararse o capturarse
├── CX_DYNAMIC_CHECK   - Se verifica en tiempo de ejecucion
└── CX_NO_CHECK        - No requiere declaracion
TipoCuando usar
CX_STATIC_CHECKErrores esperados que el llamador debe manejar
CX_DYNAMIC_CHECKErrores de programacion (indice fuera de rango)
CX_NO_CHECKErrores del sistema, raramente manejables

Sintaxis basica

TRY-CATCH

TRY.
    " Codigo que puede lanzar excepcion
    lo_object->do_something( ).


  CATCH cx_some_exception INTO DATA(lx_error).
    " Manejar el error
    DATA(lv_message) = lx_error->get_text( ).


  CLEANUP.
    " Siempre se ejecuta si hay excepcion no capturada
    " Limpiar recursos
ENDTRY.

Ejemplos

1. Crear clase de excepcion simple

CLASS zcx_order_error DEFINITION
  PUBLIC
  INHERITING FROM cx_static_check
  FINAL
  CREATE PUBLIC.


  PUBLIC SECTION.
    INTERFACES if_t100_message.


    CONSTANTS:
      BEGIN OF order_not_found,
        msgid TYPE symsgid VALUE 'ZORDER',
        msgno TYPE symsgno VALUE '001',
        attr1 TYPE scx_attrname VALUE 'MV_ORDER_ID',
        attr2 TYPE scx_attrname VALUE '',
        attr3 TYPE scx_attrname VALUE '',
        attr4 TYPE scx_attrname VALUE '',
      END OF order_not_found.


    DATA: mv_order_id TYPE string READ-ONLY.


    METHODS constructor
      IMPORTING
        textid    LIKE if_t100_message=>t100key OPTIONAL
        previous  LIKE previous OPTIONAL
        order_id  TYPE string OPTIONAL.


ENDCLASS.


CLASS zcx_order_error IMPLEMENTATION.
  METHOD constructor.
    super->constructor( previous = previous ).


    mv_order_id = order_id.


    CLEAR me->textid.
    IF textid IS INITIAL.
      if_t100_message~t100key = if_t100_message=>default_textid.
    ELSE.
      if_t100_message~t100key = textid.
    ENDIF.
  ENDMETHOD.
ENDCLASS.

2. Lanzar excepcion

METHOD get_order.
  SELECT SINGLE * FROM zorders
    WHERE order_id = @iv_order_id
    INTO @rs_order.


  IF sy-subrc <> 0.
    RAISE EXCEPTION TYPE zcx_order_error
      EXPORTING
        textid   = zcx_order_error=>order_not_found
        order_id = iv_order_id.
  ENDIF.
ENDMETHOD.

3. Capturar excepcion

TRY.
    DATA(ls_order) = lo_service->get_order( '12345' ).
    WRITE: / 'Pedido encontrado:', ls_order-order_id.


  CATCH zcx_order_error INTO DATA(lx_error).
    WRITE: / 'Error:', lx_error->get_text( ).
    WRITE: / 'ID del pedido:', lx_error->mv_order_id.
ENDTRY.

4. Multiples tipos de excepcion

TRY.
    lo_service->process_order( iv_order_id ).


  CATCH zcx_order_not_found INTO DATA(lx_not_found).
    " Manejar pedido no encontrado
    WRITE: / 'Pedido no existe:', lx_not_found->mv_order_id.


  CATCH zcx_order_locked INTO DATA(lx_locked).
    " Manejar pedido bloqueado
    WRITE: / 'Pedido bloqueado por:', lx_locked->mv_locked_by.


  CATCH zcx_order_error INTO DATA(lx_general).
    " Manejar otros errores de pedido
    WRITE: / 'Error general:', lx_general->get_text( ).


  CATCH cx_root INTO DATA(lx_any).
    " Capturar cualquier otra excepcion
    WRITE: / 'Error inesperado:', lx_any->get_text( ).
ENDTRY.

5. CLEANUP para limpieza

DATA: lo_file TYPE REF TO zcl_file_handler.


TRY.
    CREATE OBJECT lo_file.
    lo_file->open( 'data.txt' ).
    lo_file->process( ).
    lo_file->close( ).


  CATCH zcx_file_error INTO DATA(lx_error).
    WRITE: / 'Error de archivo:', lx_error->get_text( ).


  CLEANUP.
    " Se ejecuta si la excepcion no se captura aqui
    " y se propaga hacia arriba
    IF lo_file IS BOUND.
      lo_file->close( ).
    ENDIF.
ENDTRY.

6. Relanzar excepcion

METHOD process_with_logging.
  TRY.
      lo_service->do_something( ).


    CATCH zcx_service_error INTO DATA(lx_error).
      " Loguear antes de relanzar
      log_error( lx_error ).


      " Relanzar la misma excepcion
      RAISE EXCEPTION lx_error.


      " O envolver en otra excepcion
*     RAISE EXCEPTION TYPE zcx_wrapper_error
*       EXPORTING previous = lx_error.
  ENDTRY.
ENDMETHOD.

7. Excepcion con mensaje T100

CLASS zcx_validation_error DEFINITION
  PUBLIC
  INHERITING FROM cx_static_check
  CREATE PUBLIC.


  PUBLIC SECTION.
    INTERFACES if_t100_message.
    INTERFACES if_t100_dyn_msg.


    CONSTANTS:
      BEGIN OF field_required,
        msgid TYPE symsgid VALUE 'ZVAL',
        msgno TYPE symsgno VALUE '001',
        attr1 TYPE scx_attrname VALUE 'MV_FIELD_NAME',
        attr2 TYPE scx_attrname VALUE '',
        attr3 TYPE scx_attrname VALUE '',
        attr4 TYPE scx_attrname VALUE '',
      END OF field_required,


      BEGIN OF value_invalid,
        msgid TYPE symsgid VALUE 'ZVAL',
        msgno TYPE symsgno VALUE '002',
        attr1 TYPE scx_attrname VALUE 'MV_FIELD_NAME',
        attr2 TYPE scx_attrname VALUE 'MV_VALUE',
        attr3 TYPE scx_attrname VALUE '',
        attr4 TYPE scx_attrname VALUE '',
      END OF value_invalid.


    DATA: mv_field_name TYPE string READ-ONLY,
          mv_value      TYPE string READ-ONLY.


    METHODS constructor
      IMPORTING
        textid     LIKE if_t100_message=>t100key OPTIONAL
        previous   LIKE previous OPTIONAL
        field_name TYPE string OPTIONAL
        value      TYPE string OPTIONAL.
ENDCLASS.

8. Encadenamiento de excepciones (previous)

METHOD outer_method.
  TRY.
      inner_method( ).


    CATCH zcx_inner_error INTO DATA(lx_inner).
      " Envolver excepcion interna
      RAISE EXCEPTION TYPE zcx_outer_error
        EXPORTING
          textid   = zcx_outer_error=>processing_failed
          previous = lx_inner.
  ENDTRY.
ENDMETHOD.


" Al capturar, se puede acceder a la cadena
TRY.
    outer_method( ).


  CATCH zcx_outer_error INTO DATA(lx_error).
    WRITE: / 'Error externo:', lx_error->get_text( ).


    " Acceder a excepcion original
    DATA(lx_previous) = lx_error->previous.
    IF lx_previous IS BOUND.
      WRITE: / 'Causa:', lx_previous->get_text( ).
    ENDIF.
ENDTRY.

9. RAISE EXCEPTION vs. RAISE SHORTDUMP

" Excepcion manejable
RAISE EXCEPTION TYPE zcx_business_error.


" Shortdump inmediato (solo para errores criticos)
RAISE SHORTDUMP TYPE cx_sy_program_error
  EXPORTING reason = 'Inconsistencia de datos detectada'.

10. Declarar excepciones en firma de metodo

CLASS zcl_order_service DEFINITION.
  PUBLIC SECTION.
    METHODS:
      " CX_STATIC_CHECK debe declararse
      get_order
        IMPORTING iv_id          TYPE string
        RETURNING VALUE(rs_order) TYPE ty_order
        RAISING   zcx_order_not_found
                  zcx_order_locked,


      " CX_DYNAMIC_CHECK no necesita declararse pero puede
      calculate
        IMPORTING iv_value       TYPE i
        RETURNING VALUE(rv_result) TYPE i,
        " RAISING zcx_division_by_zero  <- opcional


      " CX_NO_CHECK nunca se declara
      process
        IMPORTING iv_data TYPE string.
ENDCLASS.

11. COND/SWITCH con excepciones

" COND con THROW
DATA(lv_status_text) = COND string(
  WHEN lv_status = 'A' THEN 'Activo'
  WHEN lv_status = 'I' THEN 'Inactivo'
  ELSE THROW zcx_invalid_status( status = lv_status )
).


" SWITCH con THROW
DATA(lv_priority) = SWITCH i(
  lv_code
  WHEN 'H' THEN 1
  WHEN 'M' THEN 2
  WHEN 'L' THEN 3
  ELSE THROW zcx_unknown_code( )
).

12. Excepcion en expresion de tabla

" Lanza CX_SY_ITAB_LINE_NOT_FOUND si no existe
TRY.
    DATA(ls_item) = it_items[ id = '123' ].


  CATCH cx_sy_itab_line_not_found.
    WRITE: / 'Item no encontrado'.
ENDTRY.


" Alternativa: DEFAULT para evitar excepcion
DATA(ls_item2) = VALUE #( it_items[ id = '123' ] DEFAULT ls_empty ).

13. Clase de excepcion con metodos auxiliares

CLASS zcx_validation DEFINITION
  PUBLIC
  INHERITING FROM cx_static_check
  CREATE PUBLIC.


  PUBLIC SECTION.
    INTERFACES if_t100_message.


    DATA: mt_errors TYPE string_table READ-ONLY.


    METHODS:
      constructor
        IMPORTING
          textid   LIKE if_t100_message=>t100key OPTIONAL
          previous LIKE previous OPTIONAL
          errors   TYPE string_table OPTIONAL,


      get_error_count
        RETURNING VALUE(rv_count) TYPE i,


      get_all_messages
        RETURNING VALUE(rt_messages) TYPE string_table.
ENDCLASS.


CLASS zcx_validation IMPLEMENTATION.
  METHOD constructor.
    super->constructor( previous = previous ).
    mt_errors = errors.


    IF textid IS INITIAL.
      if_t100_message~t100key = if_t100_message=>default_textid.
    ELSE.
      if_t100_message~t100key = textid.
    ENDIF.
  ENDMETHOD.


  METHOD get_error_count.
    rv_count = lines( mt_errors ).
  ENDMETHOD.


  METHOD get_all_messages.
    rt_messages = mt_errors.
  ENDMETHOD.
ENDCLASS.

14. Pattern: Result Type (alternativa a excepciones)

" Clase de resultado
CLASS zcl_result DEFINITION.
  PUBLIC SECTION.
    DATA: is_success TYPE abap_bool READ-ONLY,
          value      TYPE REF TO data READ-ONLY,
          error      TYPE REF TO cx_root READ-ONLY.


    CLASS-METHODS:
      success IMPORTING iv_value        TYPE any
              RETURNING VALUE(ro_result) TYPE REF TO zcl_result,
      failure IMPORTING ix_error        TYPE REF TO cx_root
              RETURNING VALUE(ro_result) TYPE REF TO zcl_result.


    METHODS get_value_or_throw
      RETURNING VALUE(rv_value) TYPE any
      RAISING   cx_root.
ENDCLASS.


" Uso
DATA(lo_result) = lo_service->find_customer( '123' ).


IF lo_result->is_success.
  DATA(ls_customer) = lo_result->value->*.
ELSE.
  WRITE: / 'Error:', lo_result->error->get_text( ).
ENDIF.

15. Resumable Exceptions

CLASS zcx_resumable DEFINITION
  PUBLIC
  INHERITING FROM cx_static_check
  CREATE PUBLIC.


  PUBLIC SECTION.
    " Marcar como resumible
    INTERFACES if_t100_message.
ENDCLASS.


" Lanzar como resumible
METHOD process.
  TRY.
      RAISE RESUMABLE EXCEPTION TYPE zcx_resumable.


    CATCH BEFORE UNWIND zcx_resumable INTO DATA(lx_res).
      " Decidir si continuar
      IF can_continue( ).
        RESUME.  " Continuar despues del RAISE
      ELSE.
        RAISE EXCEPTION lx_res.  " Propagar
      ENDIF.
  ENDTRY.
ENDMETHOD.

Resumen

ElementoDescripcion
CX_STATIC_CHECKDebe declararse/capturarse
CX_DYNAMIC_CHECKVerificacion en runtime
CX_NO_CHECKSin verificacion
RAISE EXCEPTION TYPELanzar excepcion
CATCH ... INTOCapturar excepcion
CLEANUPLimpieza antes de propagar
previousEncadenar excepciones

Notas importantes / Mejores practicas

  • Heredar de CX_STATIC_CHECK para errores de negocio esperados.
  • Usar mensajes T100 para textos traducibles.
  • Capturar excepciones lo mas especifico posible.
  • Usar previous para mantener la cadena de errores.
  • CLEANUP solo se ejecuta si la excepcion no se captura localmente.
  • No usar excepciones para control de flujo normal.
  • Preferir nombres descriptivos: ZCX_ORDER_NOT_FOUND vs ZCX_ERROR.
  • En RAP: usar las estructuras FAILED y REPORTED en lugar de excepciones.