Deleting a permanent object from the table messes up the loop flow

[ceieneka]

Hi,

I'm starting to play with abap and I have this problem. I get objects of persistent class into table and than iterate through it in a loop and call method which check some condition, if the condition is met I delete such object, Unfortunately this deleting breaks the loop. Here is simplify code:

...
lt_msgs = lo_agent->get_persistent_by_query( i_query = lo_query ).
LOOP AT lt_msgs INTO lo_record.
  lo_msg ?= lo_record.
  lo_msg->process( ).
ENDLOOP.

And here is the process() method:

...
  IF me->get_is_active( ) = 0.
    zca_sd_pz_msg=>agent->if_os_factory~delete_persistent( me ).
    COMMIT WORK.
  ENDIF.
endmethod.

After the first deletion in the process() method, the next objects passed through the outer loop appear to be empty - logic of process method works fine until first delete.

What I missed?

[horst_keller]

Hi,

Starting "playing with ABAP" and using persistent objects from the beginning?

Hmm, quite a task.

In fact "Object Services" are a non-trivial framework and no longer recommended anyhow (since we have RAP now).

Therefore, better start.with something more basic or, well, delve deeper:

Object Services (OS)

[ceieneka]

It took me a while to find a solution, the problem was in the way the commits were made.
Whenever a commit occurred in the process() method, it "cleared" other lt_msgs array records. Commit from the process method should be called once, after processing all objects from the loop. It should be done like this (at least it works):

...
lt_msgs = lo_agent->get_persistent_by_query( i_query = lo_query ).
LOOP AT lt_msgs INTO lo_record.
  lo_msg ?= lo_record.
  lo_msg->process( ).
ENDLOOP.
COMMIT WORK.

...
IF me->get_is_active( ) = 0.
    zca_sd_pz_msg=>agent->if_os_factory~delete_persistent( me ).
  ENDIF.
endmethod.

horst.keller : this is deep water trial 🙂

Thanks.

[harishankar714]

It seems that the issue is with the way the loop is being processed after an object is deleted. When you delete an object in the loop, the size of the table that holds the objects is reduced and this causes the loop to terminate prematurely.

To resolve this issue, you could use a different approach to iterate through the objects. One possible solution is to use a backward loop and delete the objects from the end of the table. This way, even if an object is deleted, the loop will continue to run until all the objects are processed.

[ceieneka]

I thought about it, but the debugger was showing the same number of objects in the array with each iteration except that each object had empty fields. I'll give it a shot for training purposes when I have a moment.