Broker Critera Negation weirdness

[Brendan Richards <br...@designuk.com>]

Hi, 

I've discovered some odd behavior exhibited by the broker criteria API
and I was wondering if anyone had come across this. 

My system is dynamically building complex queries by building criteria
objects one at a time and then pulling them together with addAndCriteria
and addOr Criteria. 

So my code looks something like this pseudocode:

Criteria criteria = new Criteria(); // create criteria object

while (myQuery.hasMoreElements()) {

	Criteria c1 = new Criteria(); // new criteria
	newCrit.addEqualTo("myProperty", myValue);
	if (myNegation) {
		c1.setNegative(true);
	}
	criteria.addAndCriteria(c1);
}   

So this code loops through some objects that I've created and adds a
number of criteria to a central criteria object. Each criteria may be
negated. 

My problem is that on the first call to addAndCriteria, a Criteria
object is not added to my main criteria, only a ValueCriteria. 

So say I want to do: 
WHERE  (NOT forename=brendan) AND (NOT surname IS NULL)
My code would loop twice setting values and setNegative(true) for each
sub-criteria.  

Looking at my final criteria object via getElements and printing the
types 
Using this code (with Logger being a simple class that writes output to
a file):

Enumeration critElements = criteria.getElements();
    while (critElements.hasMoreElements()) {
        Object testCrit = critElements.nextElement();
        Logger.debugLog("type "+testCrit.getClass().getName());
        if (testCrit instanceof Criteria) {
            Criteria tc = (Criteria) testCrit;
            if (tc.isNegative()) { 
			Logger.debugLog("Criteria is negative");
		}
        }
    } 

I get the following result in my logfile:
type org.apache.ojb.broker.query.ValueCriteria
type org.apache.ojb.broker.query.Criteria
Criteria is negative


Using criteria.toString() I get:

[forename = brendan, [surname IS NULL ]]




What this means is that I have completely LOST the isNegative value for
the first criteria I add. The containing criteria object is not negative
(I don't want it to be either I want to control the negativity of each
criteria I add).

Why does criteria.addAndCriteria convert a Criteria to ValueCriteria
when adding the first criteria losing the negative switch?

What I'd expect to see from criteria.toString() after the above code is:
[[forername = brendan], [surname IS NULL ]] - with both elements being
instances of Criteria.

Subsequent calls to addAndCriteria() after the first add Criteria
objects as you would expect.
[ forname=brendan, [surname IS NULL], [email IS NULL] ]


There is a simple dodgy workaround I could do where the first criteria I
add always evaluates to TRUE but this is far from ideal. 

Any Ideas?

Cheers, 

Brendan.


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