Customization of Messages for OData-services generated from CDS-Views

[benedikthoelker]

Is it possible to customize the messages for an OData-service generated from CDS views? The question has the following concrete background: We use a value help, through which the user can search for a customer (article, plant, ...). The value help pulls its data from a CDS view. If the user gives an invalid customer number and presses Enter, the OData service responds with the following message:

Resource not found for segment "Z_I_CustomerVHType". 

Unfortunately, the user can not do much with this message. In order to get a readable message, my workaround has been to redefine the respective method in the DPC_EXT of the OData service and to replace the error case with a separate message. With multiple entities this quickly leads to a coding-mess, furthermore this approach is only possible, if I redefine my service via SEGW.

Is there a better solution to this problem?

Appendix: OData error message

[Andre_Fischer]

Hi Benedikt,

when entering a non existing value for a value help in SAP Fiori Elements List Report Template you get a warning in the UI that you have entered a wrong value.

Technically a GET request is sent to the backend that returns with an empty response.

GET SEPMRA_I_ProductCategory?search-focus=ProductCategory&$filter=ProductCategory%20eq%20%27k%27
HTTP/1.1

As discussed in your case you are sending a GET request with the entered value as a key to the backend.

In order to avoid having the need to implement each single GET_ENTITY method for each value help you can redefine the generic method

/IWBEP/IF_MGW_APPL_SRV_RUNTIME~GET_ENTITY

that itself calls the entity specific Methods

METHOD /iwbep/if_mgw_appl_srv_runtime~get_entity.
    DATA lv_entityset_name TYPE string.
    DATA lr_entity TYPE REF TO data.

    lv_entityset_name = io_tech_request_context->get_entity_set_name( ).

    TRY.
        CALL METHOD super->/iwbep/if_mgw_appl_srv_runtime~get_entity
          EXPORTING
            iv_entity_name          = iv_entity_name
            iv_entity_set_name      = iv_entity_set_name
            iv_source_name          = iv_source_name
            it_key_tab              = it_key_tab
            it_navigation_path      = it_navigation_path
            io_tech_request_context = io_tech_request_context
          IMPORTING
            er_entity               = er_entity
            es_response_context     = es_response_context.
      CATCH /iwbep/cx_mgw_busi_exception .
        "CATCH /IWBEP/CX_MGW_TECH_EXCEPTION .
        CASE lv_entityset_name.
          WHEN 'ValueHelp1Set' or 'ValueHelp2Set'.
            "do some value help specific error handling

          WHEN OTHERS.

        ENDCASE.

    ENDTRY.







  ENDMETHOD.