Exception handling of CONVERSION_EXITS in /UI2/CL_JSON

[BlackmanCC]

We deserialize JSON objects into ABAP structures. The house number field is defined in a JSON integer. However, there are market partners who send the field as a string and also send non-numeric characters in the house number.
To intercept this, I have placed a conversion exit on the house number field of the ABAP target structure. The conversion exit is run through and an exception is thrown.
Unfortunately, in the RESTORE_TYPE method of the /UI2/CL_JSON class, the exception is not passed on after the conversion exit is called, but only the target field is cleared:

                       IF lv_convexit IS NOT INITIAL.
                        TRY .
                            CALL FUNCTION lv_convexit
                              EXPORTING
                                input  = sdummy
                              IMPORTING
                                output = data
                              EXCEPTIONS
                                OTHERS = 1.
                            IF sy-subrc IS NOT INITIAL.
                              CLEAR data.
                            ENDIF.
                            RETURN.
                          CATCH cx_root ##CATCH_ALL ##NO_HANDLER.
                        ENDTRY.
                      ENDIF. 

This behavior does not make sense using conversion exits as there is no possibility to perform a real check for the JSON.
It would be desirable to pass the exception to the top or to have an optional parameter that passes the error message to the top in case of exceptions in the conversion exit

[alexey-arseniev]

Hi Jens,

Thanks for the report. Yes, I see your point, but the correction I can offer here is limited. I can not propagate any exception but only CX_SY_MOVE_CAST_ERROR, and may pass your exception in the "previous" attribute. Still need a correction.

You may try it with your own copy of the class (you can download Z_UI2_JSON from GitHub) and modify the code you pasted to this one:

IF lv_convexit IS NOT INITIAL.
  TRY .
      CALL FUNCTION lv_convexit
        EXPORTING
          input  = sdummy
        IMPORTING
          output = data
        EXCEPTIONS
          OTHERS = 1.
      IF sy-subrc IS NOT INITIAL.
        CLEAR data.
      ENDIF.
      RETURN.
    CATCH cx_root INTO lo_exp.
      CLEAR data.
      IF mv_strict_mode EQ abap_true.
        RAISE EXCEPTION TYPE cx_sy_move_cast_error EXPORTING previous = lo_exp.
      ELSE.
        RETURN.
      ENDIF.
  ENDTRY.
ENDIF.

Here you can find how to generally allow passing exceptions through:

• Exception Handling in /UI2/CL_JSON

Please, check if this suggestion will help you. If yes, I will integrate it into the next patch note.

BR, Alexey.

[BlackmanCC]

Hi Alexey,

Thanks for your answer. I will try it out, but the exception is only thrown in strict mode. How can I enable strict mode when calling Z_UI2_JSON->DESERIALIZE? There is no parameter for this.

I also found out that the cx_sy_move_cast_error exception is caught in the deserialize method, but not propagated. This means I have no chance to handle the exception.

      TRY .
          CALL METHOD lo_json->(lc_method)
            EXPORTING
              json  = json
              jsonx = jsonx
            CHANGING
              data  = data.
        CATCH cx_sy_move_cast_error.                    "#EC NO_HANDLER
      ENDTRY.

Propagating the exception in strict_mode is good, if I can set strict_mode calling method deserialize and I get the exception outside the method so I can handle it.

Regards
Jens

[alexey-arseniev]

Hi Jens,

As mentioned here: Exception Handling in /UI2/CL_JSON, you must use the instance method for deserialization (DESERIALIZE_INT) to get an exception. For this, you will need to create the class instance explicitly. And when creating the class instance, you will get an option to pass STRICT_MODE = abap_true to the constructor.

BR, Alexey.

[BlackmanCC]

Hi Alexey,

The suggestion works for me. Please include it in the next patch.
Do you have a date for the next release? Is a correction note possible, which we can apply before the release? Until next release I can use the Z class from github and after release I will switch to SAP standard.

Thanks and regards
Jens

[alexey-arseniev]

Hi Jens,

I have already added the correction in the development version. The correction will be included in note 3615316 (not yet released). Details can be found on version history page.

Release data I do not know yet: normally, I try to collect some fixes together, while the process of cross-release testing and corrections is quite time-consuming, but I will try to release it in July.

BR, Alexey.