Re: [rules-users] Stateless session commands and ExecutionResults (5.5.0.Final)
I think you have to put your insert command into a list
List<Command<?>> cmds = new ArrayList();
and pass this via batch execution
CommandFactory.newBatchExecution( cmds )
-W
On 04/12/2013, Stephen Masters <stephen.masters(a)me.com> wrote:
Hi folks,
Can anyone explain how stateless session execution results should work?
Working through the docs and tracing the code, it’s getting a bit
confusing.
Firstly, according to the user manual, one should be able to insert a list
of facts as a Command, and get an instance of ExecutionResults back, which
can then be queried. Here’s the example code:
StatelessKnowledgeSession ksession = kbase.newStatelessKnowledgeSession();
Command cmd = CommandFactory.newInsertElements( Arrays.asList( Object[] {
new Cheese( "stilton" ),
new Cheese( "brie" ),
new Cheese( "cheddar" ),
});
ExecutionResults bresults = ksession.execute( cmd );
That doesn’t compile, so I fixed it as follows:
Command cmd = CommandFactory.newInsertElements( Arrays.asList(
new Cheese( "stilton" ),
new Cheese( "brie" ),
new Cheese( "cheddar" )
));
ExecutionResults bresults = ksession.execute( cmd );
This does now compile, but running it throws a ClassCastException:
java.lang.ClassCastException: java.util.ArrayList cannot be cast to
org.drools.runtime.ExecutionResults
Taking a look through the Drools code, it would appear that Command has a
generic type, which in the case of an InsertElementsCommand is:
GenericCommand<Collection<FactHandle>>
In turn, the execute command in StatelessKnowledgeSessionImpl casts its
result to that generic type:
public <T> T execute(Command<T> command) {
Object o = ((GenericCommand) command).execute( context );
...
return (T) o;
So the ClassCastException is because the execute method returns an ArrayList
of FactHandle instead of an ExecutionResults.
I’m assuming that I must have got the wrong end of the stick somewhere, so
what should I be doing to get an ExecutionResults from a stateless session,
which I can then query?
Cheers,
Steve