Handling old-style errors via class based exceptions

Handling old-style errors via class based exceptions: SAP is in an interesting spot with ABAP. There are a lot of newer and better ways to things, but a lot of old things also work. Trying to get the benefits of the new ways while using existing business logic which was written the old way always throws up some fun.

In this particular case, I will show you the solution that I have come up with to handle the old style exceptions thrown by a function module call. This method is completely generic and should work with any function module call that throws classic exceptions.

Setup

The new exception class

Create a new exception class that you will use to “translate” these messages from one format to another. In this class, you have to add 5 new attributes to carry your Message Type and Message Variables.

If you are doing this with the Eclipse environment, this is what you would declare.

CLASS zcx_my_exception DEFINITION PUBLIC INHERITING FROM cx_static_check FINAL CREATE PUBLIC . PUBLIC SECTION. INTERFACES if_t100_message . "Start of addition DATA msgty TYPE symsgty . DATA text1 TYPE sylisel . DATA text2 TYPE sylisel . DATA text3 TYPE sylisel . DATA text4 TYPE sylisel . "End of addition METHODS constructor IMPORTING !textid LIKE if_t100_message=>t100key OPTIONAL !previous LIKE previous OPTIONAL !msgty TYPE symsgty OPTIONAL !text1 TYPE sylisel OPTIONAL !text2 TYPE sylisel OPTIONAL !text3 TYPE sylisel OPTIONAL !text4 TYPE sylisel OPTIONAL . PROTECTED SECTION. PRIVATE SECTION. ENDCLASS.

The calling Methods

In this code sample, I have the key pieces of code that you will need. Please don’t pay attention to the fact that the variables and import – export parameters are not declared.

When declaring the class, all the methods have to be declared with the RAISING zcx_my_exception. This ensures that any exception that is raised is passed to the next level.

CLASS lcl DEFINITION. PUBLIC SECTION. METHODS get_master_data RAISING zcx_my_exception. METHODS call_function RAISING zcx_my_exception. METHODS call_bapi RAISING zcx_my_exception. ENDCLASS.

Standard Function Modules

First the standard function call. I have an additional method GET_MASTER_DATA( ) which is just an additional layer to show how exceptions can be handled at the highest level. For those of you who haven’t used class based exceptions in ABAP before, this is to give you a glimpse of the power and simplicity of using this over the traditional method of passing and handling the exception at every level.

CLASS lcl IMPLEMENTATION. METHOD get_master_data. "Prep the material number, etc me->call_function( ). "Post call routine - Do something with data me->call_bapi( ). ENDMETHOD.

 METHOD call_function. CALL FUNCTION 'MATERIAL_READ' EXPORTING schluessel = key_fields " Material master key fields IMPORTING matdaten = view_tab " Material master view return = return matper = matper EXCEPTIONS account_not_found = 1 batch_not_found = 2 forecast_not_found = 3 lock_on_account = 4 lock_on_material = 5 lock_on_plant = 6 lock_on_sales = 7 lock_on_sloc = 8 lock_on_batch = 9 lock_system_error = 10 material_not_found = 11 plant_not_found = 12 sales_not_found = 13 sloc_not_found = 14 slocnumber_not_found = 15 sloctype_not_found = 16 text_not_found = 17 unit_not_found = 18 invalid_mch1_matnr = 19 invalid_mtcom = 20 sa_material = 21 wv_material = 22 waart_error = 23 t134m_not_found = 24 error_message = 25 OTHERS = 26. IF sy-subrc <> 0. RAISE EXCEPTION TYPE zcx_my_exception EXPORTING textid = VALUE scx_t100key( msgid = sy-msgid msgno = sy-msgno attr1 = 'TEXT1' attr2 = 'TEXT2' attr3 = 'TEXT3' attr4 = 'TEXT4' ) msgty = sy-msgty text1 = CONV sylisel( sy-msgv1 ) text2 = CONV sylisel( sy-msgv2 ) text3 = CONV sylisel( sy-msgv3 ) text4 = CONV sylisel( sy-msgv4 ). ENDIF. ENDMETHOD.

A couple of points of note here. Always declare the extra catch all exception ERROR_MESSAGE (in this case = 25). This is a safety in case the person who programmed the function module raised an exception that was not declared. I have had crashes when I forgot to do this.

The other is the fact that I am also passing the MSGTY (Message Type). Even though the new class based exceptions are “Typeless”, because you raise different ones in different circumstances, I sometimes find it useful to have this field around. This is a personal preference, because you can certainly make the argument that all exceptions out of a function module are errors.

Using a BAPI

is similar, but instead of the SYST fields, you will be using the data from the Bapi return table.

 METHOD call_bapi. DATA: bapiret_tab TYPE STANDARD TABLE OF bapiret2. CALL FUNCTION 'BAPI_PRODORD_CREATE' EXPORTING orderdata = orderdata " Transfer Structure for Creating Production Orders IMPORTING return = bapiret_tab " Return Parameters order_number = e_order_number. " Production order number LOOP AT bapiret_tab INTO DATA(bapiret) WHERE type = 'E'. RAISE EXCEPTION TYPE zcx_my_exception EXPORTING textid = VALUE scx_t100key( msgid = bapiret-id msgno = bapiret-number attr1 = 'TEXT1' attr2 = 'TEXT2' attr3 = 'TEXT3' attr4 = 'TEXT4' ) msgty = bapiret-type text1 = CONV sylisel( bapiret-message_v1 ) text2 = CONV sylisel( bapiret-message_v2 ) text3 = CONV sylisel( bapiret-message_v3 ) text4 = CONV sylisel( bapiret-message_v4 ). ENDLOOP. ENDMETHOD. ENDCLASS.

The LOOP on the bapiret_tab is just one way of filtering the table. You can of course use the READ TABLE or table expressions (bapiret = bapiret_tab[ type = ‘E’ ] ) to achieve the same. This is where the use of the MSGTY gets interesting because a lot of BAPI’s do send back the full gamut of Warnings and Success messages too. Some time in the future, I would like to experiment with making this RAISE a RESUMABLE one, and using that to log the Success and Warning messages.

Using the exceptions

This is the easy part! Just like any other TRY… CATCH.

 TRY. DATA(obj) = NEW lcl( ). obj->get_master_data( ). CATCH zcx_my_exception INTO DATA(ocx_my). " Do some clean up work " .... " Show the user the error message MESSAGE ID ocx_my->if_t100_message~t100key-msgid TYPE ocx_my->msgty NUMBER ocx_my->if_t100_message~t100key-msgno WITH ocx_my->text1 ocx_my->text2 ocx_my->text3 ocx_my->text4. ENDTRY.

The only tricky part is how you get the MSGID and MSGNO from the exception object that has been caught – you have to go through the interface for accessing the T100 texts. So, that is a couple of layers deep.

Enjoy your errors!

Inspiration and References

This is in response to Mathew Billingham’s question of a few years ago… Handling general errors via class based exceptions I just had a similar issue and just like him I realized that the exception object carries all the information that you need.

I have also had some inspiration from Horst Keller’s post ABAP News for Release 7.50 – Converting Messages into Exceptions | SAP Blogs and also from Jörg Krause’s Blog The hassle with function module calls – part 2 | SAP Blogs and the subsequent discussions.