Thanks for replying. rule "Player 1 wins first set " when $f : Fact() eval ($f.getDetails().get("END_SET").toString() == "true" && Integer.valueOf($f.getDetails().get("SET").toString()) == 1 && Integer.valueOf($f.getDetails().get("PLAYER1_SCORE").toString()) > Integer.valueOf($f.getDetails().get("PLAYER2_SCORE").toString())) then //then settle selection; end this rules runs perfectly as long as the hashmap contained in the ‘fact’ object has all the required keys and their values are not null. For the time being I have just changed any null values to a value of ‘DEFAULT’ but it would be preferable to be able to look for f.getDetails().get("END_SET") (for example) knowing that the engine that sent it might not be in an end_set state so may not have added that key. That example is very basic but as I create more rules for more sports it could become very cumbersome to have to ensure that every key referenced in the rules is in the hashmap each time! Alex ------------------------------ *From:* rules-dev-bounces(a)lists.jboss.org [mailto: rules-dev-bounces(a)lists.jboss.org] *On Behalf Of *David Sinclair *Sent:* 24 February 2009 17:27 *To:* Rules Dev List *Subject:* Re: [rules-dev] Dealing with null pointer exceptions thrown by parsing rules 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(a)paddypower.com&gt; 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 isn’t 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, Alex ________________________________________________________________________ Privileged, confidential and/or copyright information may be contained in this communication. This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you are not the intended addressee, you may not copy, forward, disclose or otherwise use this e-mail or any part of it in any way whatsoever. To do so is prohibited and may be unlawful. If you have received this email in error please notify the sender immediately. Paddy Power PLC may monitor the content of e-mail sent and received for the purpose of ensuring compliance with its policies and procedures. Paddy Power plc, Airton House, Airton Road, Tallaght, Dublin 24 Registered in Ireland: 16956 ________________________________________________________________________ _______________________________________________ rules-dev mailing list rules-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-dev ________________________________________________________________________ Privileged, confidential and/or copyright information may be contained in this communication. This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you are not the intended addressee, you may not copy, forward, disclose or otherwise use this e-mail or any part of it in any way whatsoever. To do so is prohibited and may be unlawful. If you have received this email in error please notify the sender immediately. Paddy Power PLC may monitor the content of e-mail sent and received for the purpose of ensuring compliance with its policies and procedures. Paddy Power plc, Airton House, Airton Road, Tallaght, Dublin 24 Registered in Ireland: 16956 ________________________________________________________________________ _______________________________________________ rules-dev mailing list rules-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-dev

From: David Sinclair <dsinclair(a)chariotsolutions.com&gt; Subject: Re: [rules-dev] Dealing with null pointer exceptions thrown by parsing rules To: "Rules Dev List" <rules-dev(a)lists.jboss.org&gt; Date: Tuesday, February 24, 2009, 12:13 PM Alex, please don't take this to be picking on you; this is more a post to everyone whom reads these forums. You are not writing procedural, object-oriented, or functional code. You are writing rules to look for patterns of objects. If everything is done in an eval you are losing the majority of the benefits of using a rule engine, e.g node sharing, indexing, etc. Flesh out your object model. Assert all of your objects into Working Memory. This will allow you to reason over anything without using evals. OK -- rant off -- Alex, you may want to try and refactor your model to be more "rules friendly". That way your could write rules more like the following. when $f : Fact() Detail(name == "END_SET", value == true) Detail(name == "SET", value = 1) Detail(name == "PLAYER1_SCORE", $score1 : value) Detail(name == "PLAYER2_SCORE', value < $score1) On Tue, Feb 24, 2009 at 12:39 PM, Zevenbergen, Alex < azevenbergen(a)paddypower.com&gt; wrote: > Thanks for replying. > > > > rule "Player 1 wins first set " > > when > > $f : Fact() > > eval ($f.getDetails().get("END_SET").toString() == "true" && Integer.valueOf($f.getDetails().get("SET").toString()) > == 1 && Integer.valueOf($f.getDetails().get("PLAYER1_SCORE").toString()) > > Integer.valueOf($f.getDetails().get("PLAYER2_SCORE").toString())) > > then > > //then settle selection; > > end > > > > > > this rules runs perfectly as long as the hashmap contained in the ‘fact’ > object has all the required keys and their values are not null. For the time > being I have just changed any null values to a value of ‘DEFAULT’ but it > would be preferable to be able to look for f.getDetails().get("END_SET") (for > example) knowing that the engine that sent it might not be in an end_set > state so may not have added that key. > > > > That example is very basic but as I create more rules for more sports it > could become very cumbersome to have to ensure that every key referenced in > the rules is in the hashmap each time! > > > > Alex > ------------------------------ > > *From:* rules-dev-bounces(a)lists.jboss.org [mailto: > rules-dev-bounces(a)lists.jboss.org] *On Behalf Of *David Sinclair > *Sent:* 24 February 2009 17:27 > *To:* Rules Dev List > *Subject:* Re: [rules-dev] Dealing with null pointer exceptions thrown by > parsing rules > > > > 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(a)paddypower.com&gt; 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 isn’t 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, > > > > Alex > > > ________________________________________________________________________ > Privileged, confidential and/or copyright information may be contained in > this communication. This e-mail and any files transmitted with it are > confidential and intended solely for the use of the individual or entity to > whom they are addressed. If you are not the intended addressee, you may not > copy, forward, disclose or otherwise use this e-mail or any part of it in > any way whatsoever. To do so is prohibited and may be unlawful. If you have > received this email in error > please notify the sender immediately. > > Paddy Power PLC may monitor the content of e-mail sent and received for the > purpose of ensuring compliance with its policies and procedures. > > Paddy Power plc, Airton House, Airton Road, Tallaght, Dublin 24 Registered > in Ireland: 16956 > ________________________________________________________________________ > > > _______________________________________________ > rules-dev mailing list > rules-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-dev > > > > ________________________________________________________________________ > Privileged, confidential and/or copyright information may be contained in > this communication. This e-mail and any files transmitted with it are > confidential and intended solely for the use of the individual or entity to > whom they are addressed. If you are not the intended addressee, you may not > copy, forward, disclose or otherwise use this e-mail or any part of it in > any way whatsoever. To do so is prohibited and may be unlawful. If you have > received this email in error > please notify the sender immediately. > > Paddy Power PLC may monitor the content of e-mail sent and received for the > purpose of ensuring compliance with its policies and procedures. > > Paddy Power plc, Airton House, Airton Road, Tallaght, Dublin 24 Registered > in Ireland: 16956 > ________________________________________________________________________ > > _______________________________________________ > rules-dev mailing list > rules-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-dev > > _______________________________________________ rules-dev mailing list rules-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-dev

Drools 5.0 comes with a new API. I also suspect that the new api is located in a new package drools-api. Ideally new software written will start using the new API. Ideally it would be nice to separate the old api in a separate package called something like drools-api-legacy, and I am sure that is the goal. Would it make sense to add @deprecated to the old api? It would make thing a little bit clearer for the devs who write code against the api. regards --zoly _______________________________________________ rules-dev mailing list rules-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-dev