Recommendation on handling individual rules' exception

[Leo Lin]

Hi groups,

I'm looking for suggestion on handling exception when executing a set of rules.

We usually have 20+ rules in one session. What happened was that if one rule failed, the following rules won't be executed as well. Common failures are null pointer error on accessing fields or network call failure from Fact's function. Failures are from both LHS and RHS.

May I ask what is the best practice on handling these errors? Is there any mechanism allowing us to finish executing as much rules as possible and skip failed rules? 

(We are using Drools 8.*)

Any suggestion would be appreciated!

Thanks,

Leo

[Kiran Bhanushali]

Hey,

Have you got any solution ?

Thanks,

Kiran

[Toshiya Kobayashi]

You can use try-catch in RHS. You can also use a custom Exception handler : https://docs.drools.org/latest/drools-docs/drools/rule-engine/index.html#rule-base-configuration-con_rule-engine

For LHS, you can add null-check or use null-safe access `!.` (https://docs.drools.org/latest/drools-docs/drools/language-reference/index.html#ref-drl-operators_drl-rules).

However, there is no way to accept Exceptions in LHS. The best practice is

- Check facts before inserting to ksession

or

- Design fact classes not to allow invalid state e.g. null

Toshiya

2024年12月11日水曜日 21:33:46 UTC+9 Kiran Bhanushali:

[Kiran Bhanushali]

Thanks a lot!

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[L L]

Thanks a lot! This is super helpful