ABAP_to_the_Future

8
Business Object Processing Framework (BOPF)
In this method, you’re not interested in what has changed but rather in the actual
current field values. Although the CHECK_DELTA method is called only when the
record is changed, the CHECK method is called on the initial load of the record and
when the record is changed. If the CHECK_DELTA method decides that the determination
does not need to run, then the CHECK method is not called.
It’s difficult to come up with any meaningful examples of when you might use the
CHECK method. (Maybe you would only want to fill certain transient nodes for
invoices over $10,000 or for really tall monsters.) Therefore, just to show how
this is done, pretend that you don’t want the determination to run if a monster
has no head, because hat size and sanity become somewhat irrelevant in such a
case.
Listing 8.10 shows how to code the check for a monster having no head. The coding
is even simpler than the CHECK_DELTA method. First, you get the current values
of the header record, then you pass those values to a method of the model
class (ARE_VALUES_DERIVATION_RELEVANT) to evaluate business rules and decide if
you really need to run the determination. Just as before, if you decide that the
determination does not need to run, then you delete a record from the table of
node keys, thus stopping the determination from running.
METHOD /bobf/if_frw_determination~check.
* Local Variables
DATA: lf_determination_needed TYPE abap_bool,
lo_monster_model TYPE REF TO zcl_monster_model,
lt_monster_header TYPE ztt_monster_header,
ls_monster_header LIKE LINE OF lt_monster_header.
io_read->retrieve(
EXPORTING iv_node = zif_monster_c=>sc_node-monster_header
it_key = ct_key
IMPORTING et_data = lt_monster_header ).
READ TABLE lt_monster_header INTO ls_monster_header INDEX 1.
CHECK sy-subrc EQ 0.
lo_monster_model = zcl_monster_model=>get_instance( ls_monster_
header-monster_number ).
lf_determination_needed =
lo_monster_model->are_values_derivation_relevant( ls_monster_header ).
CHECK lf_determination_needed = abap_false.
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