如何为持久性类创建非持久性抽象超类

Question

I wanted to create an abstract super class for my persistent classes, which provides some functions to query against any other persistent class which is member of that class.

So I tried to add this abstract class as superclass, when I got following error:

The superclass of a persistent class must be persistent

Message no. OO629

Is there some kind of good workaround? (I mean something diffrent from making an Interface and Copy-Paste the functions into each subclass)

Here some additional info:

Here is what I want to do (Try IE if it does not work with chrome or friefox

Short Abstract:

• (I am working in user )
• Creating a general function to query against every key.
• Creating a more specific function using the general function to query all the "links" from a join table( user_has_tag ), filling them into a attribute
• Query the other foreignkey ( tag ) using the general function again.

Here my abstract superclass (with the general function QUERY_BY_UUID :

CLASS zcl_ps_hrmobject DEFINITION
  PUBLIC
  ABSTRACT
  CREATE PUBLIC .

  PUBLIC SECTION.

    METHODS get_uuid
      RETURNING
        VALUE(ro_uuid) TYPE uuid .
  PROTECTED SECTION.

    METHODS query_by_uuid
      IMPORTING
        !ir_agent         TYPE REF TO object
      RETURNING
        VALUE(rt_entries) TYPE osreftab
      RAISING
        cx_os_object_not_found
        cx_os_query_error .
    METHODS get_query
      RETURNING
        VALUE(rr_query) TYPE REF TO if_os_query .
  PRIVATE SECTION.

    CONSTANTS lc_query_method_name TYPE string VALUE 'IF_OS_CA_PERSISTENCY~GET_PERSISTENT_BY_QUERY'. "#EC NOTEXT
    DATA mlr_query TYPE REF TO if_os_query .
ENDCLASS.



CLASS zcl_ps_hrmobject IMPLEMENTATION.


* <SIGNATURE>---------------------------------------------------------------------------------------+
* | Instance Protected Method ZCL_PS_HRMOBJECT->GET_QUERY
* +-------------------------------------------------------------------------------------------------+
* | [<-()] RR_QUERY                       TYPE REF TO IF_OS_QUERY
* +--------------------------------------------------------------------------------------</SIGNATURE>
  METHOD get_query.
    rr_query = me->mlr_query.
  ENDMETHOD.


* <SIGNATURE>---------------------------------------------------------------------------------------+
* | Instance Public Method ZCL_PS_HRMOBJECT->GET_UUID
* +-------------------------------------------------------------------------------------------------+
* | [<-()] RO_UUID                        TYPE        UUID
* +--------------------------------------------------------------------------------------</SIGNATURE>
  METHOD get_uuid.
* must be implemented in subclass

    RAISE EXCEPTION TYPE cx_os_no_implementation
*      EXPORTING
*        textid =
*        previous =
      .
  ENDMETHOD.


* <SIGNATURE>---------------------------------------------------------------------------------------+
* | Instance Protected Method ZCL_PS_HRMOBJECT->QUERY_BY_UUID
* +-------------------------------------------------------------------------------------------------+
* | [--->] IR_AGENT                       TYPE REF TO OBJECT
* | [<-()] RT_ENTRIES                     TYPE        OSREFTAB
* | [!CX!] CX_OS_OBJECT_NOT_FOUND
* | [!CX!] CX_OS_QUERY_ERROR
* +--------------------------------------------------------------------------------------</SIGNATURE>
  METHOD query_by_uuid.
    DATA: lr_query TYPE REF TO if_os_query,
          lr_uuid  TYPE uuid.

    lr_query = me->get_query( ).
    lr_uuid  = me->get_uuid( ).

*TRY.
    CALL METHOD ir_agent->(lc_query_method_name)
      EXPORTING
        i_query = lr_query
*       i_parameter_tab =
        i_par1  = lr_uuid
*       i_par2  =
*       i_par3  =
*       i_subclasses    = OSCON_FALSE
*       i_upto  = 0
*       i_options       = IF_OS_QUERY_OPTIONS=>DEFAULT_OPTIONS
      RECEIVING
        result  = rt_entries.
* CATCH cx_os_object_not_found .
* CATCH cx_os_query_error .
*ENDTRY.


  ENDMETHOD.
ENDCLASS.

Answer 1

否。您的描述听起来像您可能想仔细看一下生成的代理类和查询服务提供的方法。

Answer 2

I solved the problem with an interface and a static helperclass.

The interface enforces three getter:

get_uuid ( )
get_query ( )
get_query_method_name ( )

Now each Element implements this interface.

In the helperclass I now have the Query_by_uuid function I wanted to heritate, which gets a Instance type of that interface ( ir_root_instance ).

Here the function

  METHOD QUERY_BY_UUID.
    DATA: lr_query             TYPE REF TO if_os_query,
          lr_uuid              TYPE uuid,
          lv_query_method_name TYPE string.

    lr_query             = ir_root_instance->get_query( ).
    lr_uuid              = ir_root_instance->get_uuid( ).
    lv_query_method_name = ir_root_instance->get_query_method_name( ).

*TRY.
    CALL METHOD ir_agent->(lv_query_method_name)
      EXPORTING
        i_query = lr_query
*       i_parameter_tab =
        i_par1  = lr_uuid
*       i_par2  =
*       i_par3  =
*       i_subclasses    = OSCON_FALSE
*       i_upto  = 0
*       i_options       = IF_OS_QUERY_OPTIONS=>DEFAULT_OPTIONS
      RECEIVING
        result  = rt_entry.
* CATCH cx_os_object_not_found .
* CATCH cx_os_query_error .
*ENDTRY.


  ENDMETHOD.