I understand what you are saying Alex, but could you post an example rule to see exactly how you are doing it? It may be that you could simply rewrite the rule so you don't get the NPE.

On Tue, Feb 24, 2009 at 4:24 AM, Zevenbergen, Alex <azevenbergen@paddypower.com> wrote:

Hi all,

I have started writing my rules packages and so have had a decent amount of success. However all my rules are based on value pairs from a hashmap object that is contained within my fact object. This approach works fine if the parameter the rule is looking for is in the map and has a value.

But I will need to be able to pass null values to the rules (and expect them to just not fire any rule that looks for that param), however this always throws a null pointer exception.

So my question is: Is there any mechanism to deal with this in drools.

Simply setting all nulls to a default value isnít preferable in this situation as the app is going to be used by several different sources and has to be able to take in many different types of info.

Thanking you,


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