CODEWITHSUNDEEP
scaladroolskiestateless-session
GroomedGorilla
GroomedGorilla

Reputation: 1002

Extracting facts/objects from DefaultFactHandle in Drools StatelessKieSession (via Scala)

I've been working with Stateful Sessions (KieSession) so far and have managed to get my project running as desired using Scala with a few Java wrappers. I am now trying to switch over to StatelessKieSessions. Based on the documentation I found, I've managed to run the following to insert objects/collections into the session, fire the rules on them and update the facts:

val cmd = CommandFactory.newInsert(myObject, "myObject")
val result = ksession.execute(cmd)

When I print result (which is of class org.drools.core.common.DefaultFactHandle), it shows the structure of the desired fact, updated as expected, preceded by something of the sort "fact 0:1:2050275256:1971742898:2:DEFAULT:NON_TRAIT:"

The documentation says that I should be able to write something like result.getValue("myObject") however this option doesn't seem to be available in Scala. (https://docs.jboss.org/drools/release/6.0.0.Beta1/kie-api-javadoc/org/kie/api/runtime/StatelessKieSession.html)

I understand that Scala-Drools interoperability hasn't been provided in full, however does anyone know of a way to extract updated facts from within a StatelessKieSession or a DefaultFactHandle containing it?

Upvotes: 0

Views: 977

Answers (1)

laune
laune

Reputation: 31300

What you get from this execute command is the fact handle of the newly inserted fact. The object therein would still be the one you have inserted, updated or not. You'll have to investigate whether this is something you can use in Scala or not.

There is no command to retrieve all facts that have been changed during the execution of a session. You'll have to monitor this, using some of the available technique.

There's not much to be gained by running a "Stateless Session". If you can achieve what you want using a regular (stateful) session, leave it at that. The stateless session may have its advantages, but don't grapple with it from Scala.

Upvotes: 1

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