Question:
What type of code must be written to avoid the cryptic NOT NULL messages when records are to be added for fields already defined with NOT NULL in the table definitions?
Answer:
The NOT NULL message is not that cryptic. It indicates that arequired field, one that is not allowed to be null, does not have a valuewhen the row containing the field is written to the database.
It’s fairly easy to check for this. At the appropriate place, you woulduse the ISNULL() method for the Value property of the fields linked to the table’s NOT NULL columns.
But where is the appropriate place? You have to do it before the row getsto the database. OPO will flush a row to the database in a variety ofcircumstances, such as moving to another container. The whole point ofthis corrective action is to inform users of a problem while they canstill fix it; for me, this means before they navigate to another row. Iwould use the Go… methods for this logic. It probably makes senseto add this logic to a user-defined method and call it from bothGo… methods. In my new book, Mastering Oracle Power Objects from O’Reilly &Associates, I explain how to create a class that will make this even easierto implement.
