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AFTER CONSTRUCT clause

Only one AFTER CONSTRUCT clause can be included into the CONSTRUCT statement. This block will be executed, if one of the following keys is pressed: Accept key, Interrupt key or Quit key. For the last two keys DEFER INTERRUPT or DEFER QUIT statements must be in effect, otherwise the program will be terminated immediately and no query will be performed.

The AFTER CONSTRUCT block is executed after the Accept key is pressed but before the Boolean expression for the query by example is created. This block can be used to validate the entered data or to save them. If CONTINUE CONSTRUCT or NEXT FIELD are included in this block, the CONSTRUCT statement will not be terminated and the cursor will return to the form.

AFTER CONSTRUCT

IF NOT field_touched(ord_id) AND NOT field_touched(cl_id) THEN

MESSAGE "You must specify either order number or the customer name to perform the query."

CONTINUE CONSTRUCT

END IF

If CONTINUE CONSTRUCT or NEXT FIELD keywords are not included into a conditional statement when used in the AFTER CONSTRUCT block, the CONSTRUCT statement will not be terminated and the user will not be able to leave the form.

AFTER CONSTRUCT clauses are not executed, and thus, CONSTRUCT statements are not completed, if:

Interrupt or Quit key is pressed with no corresponding DEFER statement in effect – a query will not be performed and the program will be terminated
4GL encounters the EXIT CONSTRUCT statement – the program control will be passed to the statements following the END CONSTRUCT statement, but the query by example will not be constructed

In these situations, the query cannot be performed, because the CONSTRUCT statement will not create the aggregate search criterion which could be used in a query.