Pre-Query - Modifying the default_where

Question

Hi,
I'm trying to get the value of the default_where clause to modify it (with set_block_property) after the user has entered the ENTER QUERY MODE and decides to RUN QUERY. I'm creating a Pre-Query event for the module component where the search criteria are entered, but it doesn't seem to work; the where_clause (l_old_where) I retrieve is always empty. My code to retrieve the default_where is:
BEGIN
DECLARE
l_block VARCHAR2(32) := name_in('system.trigger_block');
l_old_where VARCHAR2(2000);
BEGIN
l_old_where := get_block_property(l_block, default_where);
message('l_old_where =' || l_old_where); --unfortunately this message always returns an empty value
EXCEPTION
WHEN VALUE_ERROR THEN
qms$forms_errors.push(QMS$FORMS_ERRORS.MSGGETTEXT(33, 'Query criteria too complex - simplify and re-query'), 'E', 'OFG', 33);
qms$forms_errors.raise_failure;
END;
END;
Does anybody know what I am doing wrong? Do you have a better way to retrieve the default_where value?
Thanks,
Denis.

Answer 1

Denis,
The DEFAULT_WHERE is part of all queries. It is set either in the property palette at design time, or programatically at runtime. If a user does an enter query and specifies some criteria, that criteria is appended to the DEFAULT_WHERE. Thus, interrogating the DEFAULT_WHERE won't help you in this case.
There is no "nice" way to do this. You have about three triggers you can choose from, that get fired after the users has entered their criteria, but before the query is executed. One is PRE-QUERY, and I forget the other two. One of them is SET-QUERY or something like that.
What you do is interrogate the fields themselves. For example, if you have two fields: NAME and SALARY, and the user entered the criteria "A%" and ">5000", then it's up to you to examine those fields to see what the user typed. Then you can do with them what you will.
So you don't get the SQL that Forms generates, but you do get the same info that Forms uses to generate the SQL.
There is also a gotcha to look out for. When referring to fields in a block that are active during enter-query mode, use the NAME_IN builtin. For example, the SALARY field is of type number, but the criteria is ">5000". That ">" is not acceptable (normally) to a NUMBER field, so you will get errors if you do something like "message('Salary criteria: '||:block.salary);"
I hope this helps.
Regards,
Robin Zimmermann
Forms Product Management