ABAP Programming EVENTS in SAP
Below are some of the events avalable within ABAP programming
First event to be called before any of the other ABAP code is processed
Called after the abap selection screen code has been processed (i.e. parameters, select-options etc)
but before these are displayed to the user. So you can use it to initialize input fields of the selection
screen or change the default values of these before the user gets to enter data into them.
AT SELECTION SCREEN OUTPUT
This is called just before the selection screen is displayed and can be used to manipulate the actual
selection screen attributes using teh loop at screen functionality. This allows you to do things like
hide fields, grey them out so they are output only or make them intensified etc.
LOOP AT SCREEN.
IF SCREEN-name = 'P_FIELd1'.
SCREEN-INTENSIFIED = '1'.
AT SELECTION-SCREEN ON
This allows you to add processing to a selection screen field for when it is chnaged, user presses F1
or F4 etc using the following parameters
HELP-REQUEST for <parameter1> (i.e. When press F1)
VALUE-REQUEST for <parameter1> (i.e. When press F4)
RADIOBUTTON for <parameter1> (i.e. When press F4)
AT SELECTION-SCREEN ON P_FIELD1.
AT SELECTION-SCREEN ON help-request for P_FIELD1.
This is called when a new page is started with an ABAP list and is used to display a header for the list.
TOP-OF-PAGE During LINE_SELECTION
If you use the 'DURING LINE-SELECTION' addition this event is also triggered when creating detailed lists.
This is displayed at the end of each page if there is a line reservation in the addition LINE-COUNT of
the initiating statement for a page footer.
REPORT demo_rep NO STANDARD PAGE HEADING
This is the first event after all screen selection processing has been completed. If no other events are declared
then there is no need to manually code this event as all processing statements will be automatically assigned to
an implicit START-OF-SELECTION block. It is a good ideal to put it in though as it separates the code and makes
it easier to read. GGenerally you would put all you data selection ABAP code within this event.
If your report is linked to a logical database this event is called after the logical database has completely
finished its work. Otherwise this event is trigged after the START-OF-SELECTION event so you would generally use
it to processes the data retrieved in that event.